Potassium-to-Sodium Ratio Affects Overall Health
An Interview with Herb Boynton by Richard A. Passwater, Ph.D.
Part 1: Innovative Supplements Have Helped Millions
When most people think of salt and health, they think of blood pressure. Many, if not most people, are not “salt sensitive” meaning that they can eat salted French fries or potato chips and not notice a rise in blood pressure. So they may reason, “If I’m not salt-sensitive, then I don’t have to worry about my salt intake. That’s for the salt-sensitive people to worry about.”
Wrong! Salt intake, particularly the ratio of potassium to sodium in our diet, affects the functioning of every cell in our bodies!
So, even if your blood pressure doesn’t rise with increased salt intake, your rate of ageing is increasing, your arteries are stiffening, your bones are weakening, your nerve impulses are slowing, your memory is declining, your risk of kidney stones is increasing, your ability to fight against cancer is impaired and the ability to nourish every cell in your body is decreased. There is overwhelming evidence that an excess of dietary salt, coupled with a deficiency in potassium, is perhaps the single largest contributor to health problems in the U. S.
Salt can cause diseases having nothing to do with blood pressure. One could say that, to a large extent, your health depends on the balance of potassium to sodium (salt) in one’s body. By improving your potassium-to-sodium balance, you can lower your risk of heart attack, stroke, osteoporosis, asthma, ulcers, stomach cancer, hypertension and other salt-linked killer diseases. The good news is that increasing the amount of potassium in your diet can counterbalance the effects of high salt intakes.
Bringing this information to the public has been a passion of a longtime friend of mine, Herb Boynton. Herb and his colleagues-Richard Moore, M.D., Ph.D., a pioneer in potassium and sodium biochemistry, and Mark McCarty, a health researcher have written a book, The Salt Solution, that should be read by everyone. I repeat-everyone-not just those interested in health, not just those who have high blood pressure, but everyone!
There is no commercial interest in this passion of Herb Boynton. It is just that Herb developed high blood pressure at an early age, and he knew what a devastating effect that could have on his health and longevity. So, as a “labor of love,” he has researched the subject for several decades and now, in the book, in this column and in subsequent interviews with his co-authors, we are able to benefit from his experience.
Herb also is a student of the Paleolithic (Stone Age) and present-day primitive diets. One of the many good fortunes of knowing Herb for more than a quarter of a century is that there have been countless times that he has bent my ear about studies of one primitive diet or another and its health benefits. Herb has been a major contributor to the field of applied nutrition, and yet many people today may not know about his contributions, nor the research that he sponsored at various laboratories around the world. Among other accomplishments, as founder of Nutrition 21, Herb developed and introduced the first-ever selenium and chromium supplements. These nutritional products have improved the health of millions of people around the world.
Herb is “retired” now, which means that he may find more time for writing. He was one of the first to write about selenium and other trace elements in nutrition magazines. His vocabulary and elegant style are legendary, and his early (mid-1970s) articles in Let’s Live and Bestways were classics. Please join me for a chat with Herb about his important role in the natural products industry, both past and present.
Passwater: Herb, tell us about the origin of Nutrition 21?
Boynton: About 45 years ago I contracted polio. I was young and in peak physical condition; it was the last thing I expected to happen. I wondered how a vital young guy like me could get a terrible disease like that. It triggered an interest in nutrition that persists to this day. That was the primary reason I founded Nutrition 21. The year was 1973, and I was 49 years old. Nutrition 21 was founded to be a nutrition research firm, and thus began a 25-year intensive course in applied nutrition.
Passwater: You attribute your interest in trace elements to your friend Dr. Klaus Schwarz. As you know, I dedicated my 1980 book, Selenium as Food & Medicine, to Klaus. How did your friendship with Klaus come about?
Boynton: In 1972, 1 read a fascinating article in Scientific American entitled “The Elements of Life.” It discussed the manner in which Klaus had invented trace element “isolators” which could restrict the dietary content of a trace element. With the aid of these controlled diets and laboratory animals, he had been able to demonstrate the nutritional essentiality for seven or eight elements that formerly were thought to be unimportant or even toxic. These trace elements included selenium, chromium, silicon, vanadium, nickel, tin and others.
This was an utterly remarkable achievement on Dr. Schwarz’s part, and in my view he should have received a Nobel Prize. In any case, he was interested in what I was doing, and together we were able to develop an organic selenium product and later an organic chromium product, both of which Nutrition 21 introduced into the marketplace.
Passwater: Why did you choose selenized yeast to be your organic selenium compound?
Boynton: We didn’t think that inorganic forms of selenium were good choices nutritionally. We jointly decided to see if we could grow a yeast product. Yeast already is in the food supply, of course, and it normally contains significant amounts of selenium. We thought that we might be able to increase the amount of selenium normally found in yeast.
We contacted Dr. Henry Peppler at Universal Foods Corporation in Milwaukee, and he agreed to run a series of tests to see if that would be possible. The first few tests were failures, but after about five or six months, we were able to grow a yeast that contained approximately 1,000 parts per million of selenium, and it was indeed organic. A large percentage of the organically bound selenium was in the form of selenomethionine, but it also contained several selenium-peptides. We introduced that into the marketplace about 1975. Anyway, it was just in time for your 1975 book Supernutrition: Megavitamin Revolution, which told the public about your research and the health benefits of selenium.
Passwater: Well, our friendship goes back to that time. You introduced yourself to me after one of my lectures, and I had already known about you from your writings. By the way, we have more sophisticated analyses of selenium yeast now. The best that we could determine before was that selenium yeast contained largely selenomethionine, selenocystine and seleno-peptides. Now, thanks to more sophisticated techniques using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). we know that selenomethionine accounts for no more than about 20% of all selenium-containing compounds. Another group of selenium-containing compounds include selenocystine (which 1 used in any earlier research), seleno-methylselenocysteine and selenoethionine. There also is another group of compounds, mostly unidentified al this time, that make up a about 40% to 50% of all the selenium compounds in yeast. These unidentified compounds may include selenophosphates, triphenyl phosphine selenide, diselenides, triselenides and other very interesting organic selenium compounds.
Later, you introduced selenomethionine, but your next innovative product was GTF-Chromium. Before you introduced it, you permitted me to test it on diabetic mice in my laboratory. The effectiveness of GTF-Chromium was readily apparent in the diabetic mice. Diabetic mice fed the RDA of all nutrients including chromium in the form of chromium chloride grew to be obese, pear-shaped, had high blood sugar levels and were short-lived. Diabetic mice fed the same diet, except that an equal amount of chromium as GTF-Chromium replaced the chromium chloride, grew normally, were normal in shape, did not become obese, had normal blood sugar levels and had normal lifespans.
Chromium is a very important supplement and I enjoyed researching with it and writing about it in my 1982 booklet, GTF Chromium (Glucose Tolerance Factor). How did the discovery of GTF chromium come about?
Boynton: Glucose Tolerance Factor (GTF) was the description for the organic form of chromium that helped insulin function to transport the blood sugar glucose through cell membranes. It was Dr. Schwarz’s suggestion that we try to do the same thing for chromium that we did for selenium, and grow yeast with more organically bound chromium than normal. We tried to do this at the same time that we were developing selenized yeast, but-where as it took us only a few months to get a successful method of growing selenium yeast-it took us over a year to achieve a chromium yeast with organically bound chromium. GTF-Chromium was introduced into the marketplace about a year or two later than selenium yeast.
Passwater: Much of what has been reported in the scientific literature about GTF is associated with Dr. Walter Mertz. Wasn’t Dr. Mertz a colleague of Dr. Schwarz’?
Boynton: This is true. Dr. Schwarz introduced me to Dr. Mertz and I have had intermittent conversations with Dr. Mertz over the years. As you know, these two scientists were mutually responsible for determining the nutritional essentiality of chromium. I last saw Dr. Mertz about two years ago at a chromium symposium in Boston; he is now enjoying a well-deserved retirement.
We were never able to determine the precise chemical constituents of our chromium yeast, and we still haven’t. With regard to the chromium yeast, we know that the chromium is organically bound, but we were never able to elucidate the precise formula of that product. Just as you mentioned that other organic selenium compounds have been identified in selenium yeast, I am sure that there are several interesting organic chromium compounds in GTF yeast.
Later, of course, we became aware of Dr. Gary Evans’ patent on chromium picolinate, and our initial tests convinced us that this was a better form of chromium than our GTF-chromium yeast. So we licensed the patent for chromium picolinate from the U.S. government.
Passwater: That was another exciting development! I wrote a series of Vitamin Connection columns on chromium picolinate between February and June of 1989. It also became the focus of my 1992 booklet, Chromium Picolinate, and my 1993 book, The Longevity Factor. This nutrient is so important to insulin function. Also, it helps prevent damage to the body that may result from even only slightly elevated blood sugar levels. The things to watch for are glycation and the formation of Advanced Glycosylation End-products (AGEs) .
You sponsored several clinical studies and research with these compounds, particularly chromium picolinate.
Boynton: Yes, we did. The most important of these was the one that we did with Dr. Richard Anderson of the U.S. Department of Agriculture and Dr. Nancy Cheng. This research started about 10 years ago in Beijing. It first was reported at the annual meeting of the American Diabetes Association in San Francisco in June 1996 and was published in 1997 in the journal Diabetes. The paper was titled “Elevated intakes of supplemental chromium improve glucose and insulin variables in individuals with type 2 diabetes.” That study was particularly important because it demonstrated that, at both the 200 mcg and 1,000 mcg dosages, chromium picolinate had very impressive salutary effects on the blood sugar levels of nun-insulin-dependent diabetics. Moreover, benefits were observed at both fasting blood levels and levels of glycosylated hemoglobin. We were extremely pleased with the results of that test.
I might say in passing that the reason we did this in China was that no one was willing to use 1,000 mcg of chromium in the United States, despite the fact chromium is remarkably safe even at gigantic dosages. It was an irrational fear. Nevertheless, we were unable to obtain permission to do this test in the U.S. We were very grateful for Dr. Nancy Cheng for making the Beijing hospital available to us.
Passwater: Somewhere between the work on the two chromium supplements, you introduced L-selenomethionine. I believe that all of the human clinical tests with selenium have been with selenium yeast. What was the story behind selenomethionine?
Boynton: In the early 1980s, there was a scare about yeast products. Although brewer’s yeast and baker’s yeast had long been staples in health food stores, the public was misled into thinking that nutritional yeasts were related to Candida and that people should be on yeast-free diets. The truth is that nutritional yeasts are totally dead cells. There are a few strains of pernicious yeast, but these have live cells. I recall that you wrote about this ungrounded fear in this column a year or so ago. (Author’s Note: There were two columns, both appearing under the overall title “Nutritional Yeasts and Yeastophobia,” The first was published in June 1999 and featured Dr. Seymour Pomper, and the second, published in July 1999, spotlighted Dr. Jack Sobel.)
Since many people stopped taking their selenium yeast supplements, I didn’t want them to miss the health benefits of selenium, so, with time and effort, we developed L-selenomethionine supplements.
Passwater: Why did you become so passionately interested in potassium and sodium?
Boynton: In 1942, before I’d reached 18, I tried to enlist in the Navy. To my great dismay, I flunked the physical; they told me my blood pressure was too high. I did pass the Army physical, which was more lenient, and I spent the next three years in World War II.
Over the ensuing decades, my blood pressure remained high-too high to even qualify for life insurance. The fact that Nutrition 21 was a research firm immersed me in the scientific research on diet and health. One of the most important facts I learned was that correcting my potassium/sodium balance might reduce my blood pressure and my risk of heart disease as well as other diseases.
As a result, I reduced my salt intake. I began by giving up potato chips (which 1 dearly love) and ate more fresh fruits and vegetables. Changes didn’t occur overnight, but after a few months, my blood pressure dropped into the normal ranges. Now I’m in my mid-70s, and my blood pressure hovers around 115 over 75-lower than the blood pressure of many adults decades younger. I no longer worry that I might die of a stroke, as my mother, my sister and my favorite aunt did.
I do, however, continue to watch my salt and potassium intake very carefully. It’s the smallest of dietary sacrifices, and the rewards are incalculably rich.
Passwater: What you seem to have mastered so well and for so long gives many others immeasurable difficulty. There are countless numbers of people who need help in adjusting their taste to less salt in their food or in easily increasing their potassium intake. Your book addresses both concerns and we’ll chat about them later, but your mention of the word “rich” reminds me that salt was once a measure of wealth. In my 1983 book, Trace Elements, Hair Analysis and Nutrition, I point out that salt was once used as payment for goods. In fact, the word salary is derived from this practice. Then there is the phrase “not worth his salt.” Salt has been regarded very highly in the past.
Boynton: Salt is more than a seasoning, and salt craving is almost universal. Several countries even have taxed salt. In India, Mahatma Gandhi led a “salt march” in 1930 to protest the British policy of monopolizing the production, sale and taxation of salt. In 18th-century France, where salt was very expensive and heavily taxed, 10,000 people a year were arrested for smuggling salt-and 300 a year were hanged.
Salt is indeed an essential nutrient, and it used to be scarce. For about 99.5% of human history, salt was so scarce that our bodies learned how to hoard it. It used to be that we had far more potassium in our diet than sodium. Paleolithic diets had about 16 times more potassium than sodium, whereas modern “civilized” diets have about 1.6 times more sodium than potassium.
Through the millennia, our- bodies learned how to hang on tenaciously to sodium and squander potassium. Because sodium has been so scarce in diets until modern times, our bodies developed mechanisms to hang onto every morsel of sodium it could. The sodium-potassium pumps in the kidneys are different than those in other tissues and they function to return sodium back into the bloodstream. Now our diets consist largely of processed foods instead of whole foods. Food processors refine foods in such a way as to reduce potassium and then they add salt to satisfy our cravings and taste preferences. The result is that millions of Americans suffer from a silent but deadly deficiency of potassium, while consuming massive amounts of salt. We eat more than a week’s worth of salt every day-while eating only two-thirds as much potassium as we should.
Passwater: As far as I am concerned, the most important finding in your book is that an unbalanced, upside-down ratio between potassium and sodium can affect every cell in the body and greatly affect health and longevity. This is not just a blood pressure thing. Please elaborate.
Boynton: Our bodies have trillions of cells, and each and every cell is dependent on the balance between potassium and sodium. These two electrolytes power the cell membranes to move many biochemical compounds in and out of the cells. Potassium and sodium, using energy produced from food “burned” by the cell in the form of adenosine triphosphate (ATP), act as a pump to move compounds through the cell membranes. This is commonly called the “sodium-potassium pump.” The sodium-potassium pump is essential to every cell in your body, and it is a component within all cells of almost all animals on earth-even one-celled animals.
Passwater: That’s an important point. When students learn about the sodium-potassium pump, they are told of its importance in nerve, muscle, gastric or kidney cells, but few appreciate the fact that the sodium-potassium pump is critical to every cell. In fact, the energy used by all of these tiny sodium-potassium pumps amounts to one-fourth of the calories consumed by people in calorie balance. Our bodies wouldn’t spend this much energy on one function unless there was a very important reason. Just what are these pumps doing and why?
Boynton: The pumps actually are proteins in the cell membranes that pull potassium into the cell interiors and push sodium out. Because the pumps move more sodium out than potassium in, they generate a voltage between the inside and the outside of the cell.
Passwater: The passive transport via diffusion would allow the sodium and potassium to equilibrate on both sides of the cell membrane, and thus there would be no electrical charge. However, the active transport of the pump, which requires energy, concentrates potassium inside the sell and sodium outside the cell.
Boynton: Yes, the pump moves three sodium ions out of the cell for every two potassium ions it brings in. Since both sodium and potassium ions have a positive charge of one (valence), the result is that there is a net transfer of positive charges out of the cell.
Passwater: The pumping action against the gradient is brought about by a protein commonly called “sodium, potassium ATPase,” which functions by conformational changes that can attract or repel one of the ions or the other. The conformation change by the protein requires energy from ATP But we still haven’t explained why building up this charge, a voltage across the cell membrane, is so important.
Boynton: Well, the electrical potential, the voltage, is like a battery and is capable of doing work. This is called the “sodium battery.” One of the key things that this sodium battery does is to drive electrical signals along nerves. It also determines the tension and relaxation of muscle cells by its effect on the calcium pump. And cells couldn’t make the proteins they need without the amino acids that are transported through the membrane with the help of the sodium battery. It also enables glucose to enter the cell against the gradient and to become fuel for the energy of the cell to perform all of its functions.
Passwater: OK, I think that our readers get the idea that the potassium-to-sodium balance is indeed critical to the functioning of every cell in our bodies. It appears that if the potassium-to-sodium balance is not right, then the sodium battery does not become fully charged and the electrical potential of the cell membrane is diminished. This, at first, has the effect of stiffening the membrane and decreasing the flow of nutrients into the cell. In essence, the membranes function like aged membranes. The body is aging biochemically. If the voltage further decreases, channels and pores in the membrane may malfunction. Eventually, various illnesses develop. We’ll talk more about the calcium pump later on when we talk about why an imbalance of potassium and sodium may be more to blame for osteoporosis than a lack of calcium.
Now that we have given a simplified explanation of the sodium-potassium pump and its importance to overall health, we should point out to our readers that one of your co-authors, Richard D. Moore, M.D., Ph.D., is a pioneer in researching the sodium-potassium pump. How and when did you meet Dr. Moore?
Boynton: Dick and I have been friends for about 20 years. He is now professor emeritus of biophysics, State University of New York. His 1986 book, “The K Factor” was the seminal book for the public on the importance of the potassium-to-sodium ratio. He also wrote a second book, The High Blood Pressure Solution, which is similar to The K Factor but uses language that is easier for the average person to understand. Both books, I thought, were excellent, and it bears saying that Dr. Moore probably knows more about potassium-sodium relationships and the sodium-potassium pump and its relation to general health than anybody else. We were extremely fortunate to secure his assistance as a co-author.
Meanwhile, it should be pointed out that our book is not a technical book. We don’t dwell on the science of the sodium-potassium pump. Rather, we concentrate on practical aspects and teach readers how easy it is to make the dietary changes that will improve their health.
Passwater: I found the book very clear and reader-friendly, with lots of practical advice. Your other co-author is Mark McCarty, who formerly was your research director at Nutrition 21. How did you meet Mark?
Boynton: When I started Nutrition 21, I hired medical students from the University of California in San Diego to do research for me. There was a succession of five or six very bright kids who helped me out in the early years. I couldn’t afford to hire anybody full time. The brightest of them all was Mark. He was a third- year medical student at the time, and he became extremely interested in nutrition, eventually deciding he would rather be a research biochemist than a medical doctor. So we hired him full time, and he has been enormously important to Nutrition 21. Mark is an extremely bright young man.
Passwater: Well, when a Mensa-qualified person like you calls someone else bright, that is saying a lot. So, as I see it, you have blended your experience as both a supplier of nutrients and a patient who had to learn to balance sodium and potassium, Dr. Moore’s experience with the sodium-potassium pump and Mark McCarty’s medical research experience, and you have written The Salt Solution. What other diseases besides hypertension do you discuss in the book?
Boynton: Initially, we were interested primarily in the high blood pressure/stroke situation, but the more research we did the more it became evident that potassium-sodium imbalance is linked to a number of other diseases, and among these is osteoporosis. In a metaphorical sense, excess salt simply sucks calcium out of the bones. I would say that a high-salt diet probably is a greater hazard for osteoporosis than a low-calcium diet. By merely reducing salt consumption to rational levels, the problem of osteoporosis can be greatly ameliorated.
Passwater: This is due to the effect of the sodium-potassium pump on the calcium pump. Please elaborate a little on the calcium pump.
Boynton: Earlier, we talked about how the sodium-potassium pump uses the energy from food to make a “sodium battery.” The calcium pump removes calcium from cell interiors by letting some of the sodium back in. In effect, the sodium is trying to get back into the cell, drawn by the charge differential. Remember, the cell interior has a negative charge that attracts ions such as sodium. The membrane protein, calcium ATPase, could be called the calcium pump. It is like a wheel that loads up three sodium ions on one side and one calcium ion on the other. This “wheel” also is powered by ATP. Since calcium has a charge of plus two (valence), the net effect is that the negative charge on the cell interior is reduced and calcium is removed…
Passwater: …from the cell. So the imbalance of potassium and sodium results in calcium being forced out of cells. Oops, I seem to have interrupted you. You were discussing other salt-related diseases.
Boynton: We also found a relationship to asthma and clear relationships to gastric cancer, ulcers and, surprisingly, to age-related cognitive memory decline. The data there are very, very impressive. It seems absolutely true that sustained isolated systolic blood pressure is a factor in dementia and in memory decline in older people and, possibly, even in younger people as well.
Passwater: OK, we have introduced all three authors and set the stage. In Part 2, planned for the June issue, we will discuss more specifically the benefits of improving the potassium-to-sodium ratio and the consequences of not doing so. Plus, we will zero in on some easy and practical tricks to improve one’s potassium-to-sodium balance. WF
Part 2: Imbalance Often Leads to Hypertension
In April, we discussed how modern diets, high in processed foods, cause an imbalance between sodium (salt) and potassium that affects every cell in the body and can lead to more than 10 diseases. We interviewed Herb Boynton, co-author of The Salt Solution (along with Richard D. Moore, M.D., Ph.D., and Mark McCarty), and learned how this potassium-sodium imbalance is the cause of high blood pressure (essential hypertension), the main cause of stroke, and contributes to heart disease, memory decline, osteoporosis, asthma, ulcers, stomach cancer, kidney stones, and cataracts, and possibly be involved with erectile dysfunction and rheumatoid arthritis. Clearly, the best way to get potassium and sodium back into satisfactory balance is to eat whole foods. When you eat whole, unprocessed foods, you are not going to get very much sodium, but you are going to get very large amounts of potassium. For 90 persons out of 100, that would be an immense improvement in their overall diets.
Dr. Richard D. Moore is our guest for this column. He received his medical degree from the Indiana School of Medicine and his doctorate in biophysics from Purdue University. He is professor emeritus, State University of New York at Plattsburgh.
Passwater: When people say, “I am not concerned about salt because I am not salt-sensitive” or “I can eat all the potato chips I want, and my blood pressure doesn’t change; therefore, salt is no problem for me,” are they missing the boat?
Moore: Absolutely. It is not simply a question of blood pressure. People can have normal blood pressure and still have serious metabolic problems that result from this potassium-sodium imbalance. In turn, these metabolic problems can lead to any of more than 10 diseases, including osteoporosis, asthma, kidney disease, kidney stones, mental decline, stomach cancer, ulcers and others.
Passwater: To help people recognize foods and diets that cause potassium/sodium imbalances, you have devised the “K Factor” to simplify the potassium-to-sodium ratio concept. Instead of having to mentally juggle and compare the two large numbers for potassium and sodium levels, the K Factor is one number that is easier to handle for comparisons.
Moore: “K” is the chemical symbol for potassium, derived from the Latin word kalium. The higher the K Factor, the better the food or diet. Soybeans have a K Factor of 340. Corned beef hash has a K Factor of about 0.37. Selecting mostly foods with a high K Factor will allow you to include some foods with poorer K Factors. The K Factor of the total diet is the important number.
Passwater: You recommend that diets have a K Factor of at least four. Why?
Moore: When I looked at all the published data for both potassium and sodium in the diet — or in the urine which reflects the diet-and then looked at the incidence of hypertension, I could see that, as the K Factor got above one or two, there was significantly less hypertension (high blood pressure). I chose a K Factor of four because of all the diets where there was any significant occurrence of high blood pressure, the K Factor was less than three. Actually a diet with a K Factor of three or above is not bad, but, for practical purposes, I think a K Factor above four is a better goal. Of course, even higher than that would be better in terms of general health. I say this based upon the fact that our ancestors had a K Factor of about 16 to 1 and we evolved having a K Factor something like that.
Passwater: You’re saying that modern diets have a poorer K Factor than diets based mostly on whole, unprocessed food?
Moore: Let me give you a very interesting statistic. In 1985, The New England Journal of Medicine published an article titled “Paleolithic Nutrition.” The authors, who had credentials as anthropologists specializing in the Paleolithic era, determined that, on average, our caveman forebears got around 11,000 mg of potassium daily and about 700 mg of sodium. This, by the way, is about the same ratio that modern-day hunter / gatherers have. It works out to a dietary K Factor of 15.7.
Today, in the United States, that 11,000 mg has shrunk to 2,500 mg of potassium. Meanwhile, the sodium intake has increased from 700 mg to 4,000 mg. This is a K Factor of 0.6. You would not expect that any animal species, human or otherwise, could live for several million years with a huge potassium intake and rather modest amounts of sodium and then suddenly flip-flop this ratio with impunity. The scientific literature supports our conclusions.
There is absolutely no doubt that the imbalance thereby produced influences at least ten serious diseases and very probably several others. This is why we think The Salt Solution is an extremely important book, and we hope that people will read it. It will enable them to correct this huge dietary error. A daily ration of 2,500 mg of potassium is far too little. And, of course, as virtually everyone should know, 4,000 mg of sodium is at least ten times as much sodium as people need.
Passwater: What about the diets of the remaining “primitive” peoples of today?
Moore: One factor that was a big influence on us in writing our book was the work done by Drs. Dennis Burkitt and Hugh Trowell. They wrote the book Western Diseases and Refined Carbohydrate and Disease, as well as several others. In Western Diseases, Dr. Trowell states, “Ethnic groups who do not add common salt to their food have lifelong low blood pressure; no exception to this generalization has been traced.” That really made an impression on me. The Yamomano Indians in Brazil have excellent blood pressure and they also — hear this! — get less than 100 mg of sodium daily versus the 4,000 mg that the average person in the United States consumes.
Passwater: At least our readers understand the value of eating whole foods and holding back on their intake of heavily processed foods.
Moore: You’ve hit on something that I really would like to emphasize; if you take any unprocessed fruit or vegetable, in 99% of all cases, such foods will have 20 to 100 times as much potassium as sodium. Unprocessed foods have a high K Factor, that is, much more potassium than sodium. This is because the sodium-potassium pumps in their cells work to keep potassium in.
If you take foods like meat, fish, fowl, eggs and dairy products, 99% will have at least three, four or five times as much potassium as sodium. The key factor is to eat whole unprocessed foods. If people ate only whole, unprocessed foods and used salt modestly, there would be no problem with potassium-sodium imbalance. Nevertheless, The Salt Solution and The High Blood Pressure Solution list foods that are particularly high in potassium and also list the major sodium villains.
Passwater: Are we engaged in a hopeless battle? As we know, for some reason, people tend to prefer the convenience or the taste of processed foods. It has just gotten out of hand.
Moore: The statistics show that 80% of the calories consumed by Americans today come from processed foods. Most of these processed foods not only have huge amounts of salt added, but in a great many cases, large amounts of potassium have been depleted. Typical of this is polished rice; three-fourths of the potassium in polished rice disappears. It is about the same with wheat. About three-quarters of the potassium is removed from the wheat berry by reducing it to white flour. We have a double whammy here, with huge amounts of salt being added, and, in a great many cases, potassium being removed.
The shame of it is that it is so easy to increase potassium. As I mentioned, just about any whole food that has not been processed is loaded with potassium. This includes bananas, oranges, apples, rutabagas and cabbage. Potatoes are one of the richest sources of this mineral. A big baked potato, for example, will have about twice as much potassium as a banana but a lot of people will add salt to their baked potato in some form or another, and that is counterproductive
Passwater: What about cow’s milk?
Moore: Cow’s milk has a K Factor of 2.8. It also is true that even though ocean fish live in a high-salt environment, they still have three to five times as much potassium in the flesh as sodium. So don’t rule out salmon, tuna, sardines or any marine fish, because they all are quite high in potassium and quite low in sodium. If you eat the canned variety of these fish, however, you have to be careful they are not loaded with salt.
Passwater: Is there a good way to supplement diets to improve the potassium content? How about salt substitutes?
Moore: The Finnish people developed a product that they call “PanSalt,” which is known in the United States as Solgar Heart Salt or Cardia Salt. Most people can’t tell it from ordinary salt, yet it has far less sodium than ordinary salt. It also has quite a lot of potassium in it. Over in Finland, the results have been utterly remarkable. Substitution of this flavoring alternative has caused an astonishing 60% drop over the past 20 years in premature deaths from stroke and heart disease, and a drop of 10 points in average diastolic (bottom number) blood pressure. I must add that these people are also admonished to eat high potassium foods and keep their sodium consumption down in general. Whatever the reason, there has been an astonishing reduction in both high pressure and stroke in Finland, where consumer acceptance of PanSalt has been so strong that there are now more than 1,000 processed foods seasoned with the product. This is a significant step.
Passwater: Tell us more about this salt substitute and the studies done with it.
Moore: Solgar Heart Salt/Cardia Salt contains 54% less sodium (by volume) than regular table salt and also contains 176 milligrams of potassium and 13 milligrams of magnesium in each quarter-teaspoon serving. An important factor is that it doesn’t taste bitter as many other salt substitutes do that contain potassium. A taste test conducted by Tuft’s University Health & Nutrition Newsletter (May 1997), found “most tasters found Solgar Heart Salt/Cardia Salt more palatable – and more like salt – than the other salt replacers they tried.”
We report in The Salt Solution a clinical study of 24 patients being treated for high blood pressure where Solgar Heart Salt/Cardia Salt was substituted for regular salt, in combination with patient education and lifestyle modification, significantly reduced their systolic by pressure by 8.8 points, on average, and their diastolic blood pressure by 7.1 points. The researchers remarked, “The significant decrease in blood pressure was seen in patients who were taking stable doses of antihypertensive medications, despite constant weight and no measurable increase in exercise.” (Phillips, 1998)
Another clinical trial that we report involves 233 hypertensive patients who substituted Solgar Heart Salt/Cardia Salt for table salt for six weeks significantly reduced their systolic blood pressure by 4.2 points and their diastolic blood pressure by 2.7 points. The researchers concluded, “Solgar Heart Salt/Cardia Salt tastes like regular salt and provides a practical means to help patients achieve a diet lower in sodium and higher in potassium.” (Whelton, 1997)
Still another clinical trial of 30 subjects found that the substitution of Solgar Heart Salt/Cardia Salt for regular table salt significantly lowered systolic pressure by 7.4 points and diastolic pressure by 3.6 points in just five weeks. (Kawasaki and Itoh, 1996)
Passwater: The blood pressure decreases may seem relatively small, but we should keep in mind that these studies are short and that the differences can be significant over the long term. As shown by the Finnish studies, the effect on stroke was quite dramatic.
Moore: Readers of The High Blood Pressure Solution report very dramatic decreases to below 120/80, even if starting the program over 160/110.
Passwater: A health claim recently has been approved that says, more or less, that food labels can mention potassium in relation to stroke.
Moore: It is a big step forward. The Tropicana Orange Juice people are advertising this fact, which is very much to their credit. But it bears emphasizing that this is not true of just orange juice, but is true of almost all whole fruits and vegetables. Most fruits, vegetables and legumes are loaded with potassium, and most of them have very little sodium. The only vegetable that I can think of that has fairly heavy amounts of sodium is celery, and it doesn’t have all that much. It still is very favorable in terms of potassium content.
Passwater: Average citizens, if they know about potassium at all, frequently come to this knowledge only after a doctor has prescribed a diuretic (to reduce excess retained water) and then told them to eat bananas to replace the potassium that has gone out with the water. The thinking appears to be that high blood pressure and too much water retention are not a good combination. So let’s get rid of the water. But, in the process, minerals such as potassium also are depleted.
Moore: First of all, The Salt Solution is not anti-drug. However, many people can restore their blood pressure to normal limits simply by increasing potassium and by reducing sodium from this ridiculously high 4,000 mg a day to somewhere between 500 and 1,000 mg a day.
Passwater: OK, I believe that we have established the practical benefits illuminated by your findings. Now, let’s chat about the details of the work itself, which, in my opinion, is Nobel Prize stuff on a level with the discoveries of the structure of DNA and the Krebs Cycle. You’ve helped elucidate one of the cell’s basic mechanisms, and, along the way, you seem to have proven the connection between potassium-salt balance and blood pressure. What got you started?
Moore: I got into this not because I was interested in any particular disease, but because I was interested in basic physical mechanisms of how the cell works and how the sodium/potassium pump is involved. When I was a graduate student at Purdue’s Physics Department in 1958, I decided to work on that mechanism. I had heard Professor Lorin Mullins, head of the Department of Biophysics at the University of Maryland, refer to calculations that indicated that the sodium pump in a resting cell used almost a quarter of all the energy available. Any mechanism that uses that much energy has got to be important. If you looked at the power distribution in a city and you found one operation in the city was using a quarter of all the electricity, you would think it was an awfully important operation.
When I did some of my early studies about the functioning of the sodium/potassium pump, I uncovered some clues that led me to think that insulin might be affecting it. Later, my group-and also that of Dr. Torben Clausen in Denmark-demonstrated that insulin does indeed regulate the sodium/potassium pump. That is pretty well established now. Additionally, with the help of research by Dr. Ken Zierler at Johns Hopkins University, we know that the action of insulin on this pump occurs at concentrations even lower than those required to affect glucose uptake in cells. This is another clue that insulin action on the pump is awfully important.
Then some theoretical analysis suggested that insulin might be raising the pH (measure of acidity or alkalinity) inside cells, thus making the cell interiors more alkaline. We did experiments in that area, and we were the first to show that is indeed the case. People used to think pH inside cells was constant. Before we did the experiments, I made a habit of asking any biologist or biochemist I would meet at a scientific conference-at least three dozen, I would estimate-“Is the pH inside the cell variable or constant?” The answer invariably was that it had to be a constant. “Why,” I would ask. “Because every enzyme is affected by pH,” they would invariably answer. It is true that every enzyme is affected by pH, and everyone was assuming — as I had originally — that the pH in the cell was therefore constant.
Of course, the corollary hypothesis is that there is a pattern to the enzyme pH profile, which is indeed the way it turns out. The pH is not constant, but is a physiological variable. The pH level is involved with regulation of glycolysis, and to some extent, cell division.
Three or four people besides myself had begun working on regulation of pH. Before long, a couple of the others showed that one way to accomplish this regulation is via the sodium/hydrogen exchange pump, whereby sodium leaks back into the cell due to a difference in its energy gradient. Technically, the electrochemical potential — or free-energy gradient — provides the energy to move a proton, which is acid or a hydrogen ion (H+) out of the cell.
That was a possible way to explain our observation of insulin-increased pH. So we undertook experiments that confirmed our theory. Those experiments, incidentally, were very gratifying because they were based on a thermodynamic mathematical analysis that makes predictions which we verified, namely, that at a certain calculable value of extracellular sodium, if the sodium is lowered by replacing it with magnesium or sucrose, the sodium/hydrogen exchange pump no longer works. Further, if the sodium is lowered below that point where the insulin stimulated it, it should make the pH more acidic. And that’s what actually happens. This is neat: just by changing the sodium outside the cell, you can convert the action of insulin on glycolysis from stimulation to inhibition.
Passwater: In other words, the pH would go down (more acidic) instead of going up (more alkaline), which is what it normally does.
Moore: Indeed, that is the case. Our work was pretty decisive, but the finding has been ignored by most researchers. But a lot of our other findings on insulin and pH haven’t been ignored. In fact, there are a lot of researchers following up on this now. What’s disappointing is how few of them are referring back to the original papers written by our group.
Parenthetically, we showed this is the way that insulin affects and stimulates glycolosis: if we lowered the sodium outside the cell below this particular value that can be calculated, we found that insulin-instead of stimulating glycolosis-inhibits it. All this without adding any foreign chemicals. This is a pretty convincing conclusion.
In the process, other people with whom I had worked, including my former major professor, showed that besides the sodium/hydrogen exchange pump, there is a sodium/ calcium exchange pump. This sodium/ calcium exchange pump moves three sodium ions into the cell in exchange for one calcium ion going out.
Passwater: Let’s remind our readers that calcium ions have a charge of “plus two,” whereas potassium ions and sodium ions each have a charge of “plus one.”
Moore: Yes, and now this is a stociometric ratio of 3 to 2 in terms of charges and 3 to 1 in terms of ions. This is opposed to the sodium/potassium exchange pump which is not stociometric.
Passwater: For our non-chemist readers, stociometric merely means a constant proportion is involved. Chemists use this term to describe relationships in which the proportion of the elements involved follow the Law of Constant Proportions.
Moore: The sodium/potassium pump does not have a fixed ratio of sodium to potassium ratio, although textbooks find it convenient to say it is a 3 to 2 ratio.
The sodium/calcium exchange is electrically not neutral, so, therefore, the membrane potential affects that. A higher membrane potential will tend to make that pump move calcium out. At each cycle, that pump moves a positive charge in. The other thing that will make it move calcium out is lowering the sodium inside the cell.
About the time all this was worked out, a researcher called me about an article that I had written about a compound that could stimulate the sodium pump. In the paper, I had mentioned that this compound acted like a “super potassium ion.” He was interested in that, and I wondered why. It turned out that he was doing experiments on high blood pressure and he, as well as others, had found a substance in the blood of people with high blood pressure that tends to inhibit the sodium potassium pump.
That was when the proverbial light bulb came on in my brain. I realized that if you inhibit the sodium/potassium pump, of course sodium is going to build up inside the cell. Inhibition of the sodium/potassium pump also causes the plasma membrane (the outermost of the cell’s “skin”) potential to decrease.
Both of these effects are going to affect the sodium calcium exchange pump in a way that will make it work less actively. Therefore, you are also getting an increase of calcium inside the cell. It is possible, in fact, to calculate exactly what the limits of that increase would be. I believe it was Dr. Mordecai Blaustein, head of the Department of Physiology at the university of Maryland, who showed something like a 5% increase in sodium inside the cell. And this, he said, results in about a 150/cr20% increase in calcium in the cell. It is something like that order of magnitude. Drs. Blaustein and Mullins were both at the University of Maryland, and their groups, as well as a group at Cambridge, had worked out this sodium/calcium exchange pump.
So we now know that this mechanism, the sodium/ calcium pump, is very sensitive to a slowdown of the sodium/potassium pump. Therefore, calcium is going up in all the cells of the body, because we know that a decrease in the potassium and an increase in the sodium in people with high blood pressure is occurring in all the cells of the body-not just the arterial wall cells. But, if one thinks for just a moment-as this researcher who called was thinking: the smooth muscle cells around the small arteries or arterioles control blood pressure. Add to this the fact that the trigger for causing muscle contractions is calcium, and it becomes obvious. It was one of those things where two and two were sitting there in front of me and I hadn’t bothered to add them together.
What suddenly came to me was the recognition that as calcium goes up in those muscle cells, the muscles are stimulated to contract and constantly constrict the blood vessels. This, of course, raises blood pressure. Dietary sodium can be the cause of the increased calcium in these cells and the resultant constricted blood vessels. Potassium would, of course, stimulate the sodium/potassium pump and, thus, indirectly, through the resulting increase in sodium-calcium exchange, decrease the intracellular calcium and allow the muscles in the blood vessel walls to relax.
It immediately hit me-why would anyone want to use this so-called “super potassium” instead of using potassium itself? After all, the compound that I had reported on as a “super potassium” presented problems. I had reported in the article that this so-called “super potassium” punches holes in cell membranes over time. I wouldn’t go near it, It was bound to be extremely toxic.
Of course, potassium ions are natural things and can’t be patented. However, new compounds can be patented and used as drugs. So I tried to speak to the people at the Hypertension Society about the benefits of the natural compounds of potassium over the synthetic drugs, but they didn’t want to talk with me or any of my group or the other researchers that I mentioned. That’s why I wrote my first book with Dr. George D. Webb — The K Factor: Reversing and Preventing High Blood Pressure without Drugs(Macmillan, 1986) Why deal with possible dangerous drugs when simple natural substances can do better and more safely?
I wanted this information out in the physicians’ and public’s hands.
The idea for writing The K Factor wasn’t mine. The other researchers also were perturbed because no one would listen to the basic truths we were unearthing. Dr. Mullins especially was annoyed because he had had a similar experience. He couldn’t get the cardiologists to listen to the thesis that sodium-calcium exchange is involved with the action of digitalis-increased strength of contraction even though the facts were published in the scientific literature. So he wrote a book about it, We knew we weren’t going to get the Hypertension Society to pay attention, so we decided to leapfrog them and go directly to the practitioners and public. I also took the message to the radio and TV airwaves.
Initially. I thought that supplemental potassium alone would be enough to lower blood pressure. But, as I got into it further and really thought it out, I could see it is a lot more than that. A low ratio of potassium to sodium may be the cause of high blood pressure, but blood pressure is not the whole problem. It’s very much like dealing with a fever that is caused by an infection.
The elevated body temperature, if it gets high enough, can cause damage, but treating the fever without treating the infection is not the total answer. We try to bring this out in The Salt Solution and in The High Blood Pressure Solution. This potassium-sodium imbalance is a big, big health problem. But, it has been hard to get people to pay attention to it, Now, we are finding that physicians who treat stroke patients are becoming interested. It seems that treating strokes is one of the most discouraging things you can do in medicine.
As I indicated, this potassium/ sodium imbalance is present in every cell in the body. We now have very strong evidence-not totally conclusive, but very strong evidence-that this potassium/ sodium imbalance also is a cause of insulin resistance. Furthermore, this potassium/sodium imbalance, which contributes to insulin resistance also is associated with an abnormal metabolism of carbohydrates and fatty acids, and may contribute to causing Type 2 diabetes. I just mentioned that the Hypertension Society people did not want to listen to us. Well, we had the same experience with the Diabetes Society when Dr. Ken Zierler and I tried to show them the link between sodium and insulin resistance.
I predicted in 1986 in The K Factor, that this potassium/sodium imbalance would be causing other disease states and I mentioned it again briefly in my 1993 book, The High Blood Pressure Solution: Natural Prevention and Cure with the K Factor. (Healing Arts Press) Now, The Salt Solution documents the fact that there are indeed quite a few other disease states caused by this potassium/ sodium imbalance. These relationships all have been discovered in the past five to seven years, and my guess is that we will find even more.
Passwater: I understand that you have updated The High Blood Pressure Solution and that the revision is in press now.
Moore: Correct. There are a couple of things worth noting with regard to high blood pressure. One is that vegetarians almost never get high blood pressure. That simple fact should say to people in flashing neon lights that hypertension is obviously something about diet. First, we know, from other lines of evidence, that there is a potassium/ sodium ratio which is extremely high in that kind of diet, and you don’t have to be a vegetarian to get that kind of ratio.
What I did was rank diets of various groups of peoples by the ratio of potassium to sodium in the diets. I found that when you have people with diets better than three-to-one potassium over sodium, you don’t see any significant incidence of hypertension. When the diets get down to two-to-one, you begin to see a noticeable incidence of hypertension and when they get down below a one-to-one ratio, there is a lot of hypertension. I chose four-to-one to allow for a margin of error. Of course, we evolved on a much higher ratio than that, about 16-to-0ne. Even relatively recently in history, before food processing, except for the peoples using salt to cure things, the ratio was above four-to-one, closer to ten-to-one. Even meat has a ratio of a little over three-to-one. Kosher meat is probably higher because most of the sodium is in the blood, which is eliminated.
The experience in Finland shows what can be accomplished by just going part way — by using a salt substitute that replaces 28% of the sodium with potassium and another 12% of the sodium with magnesium (a total of 40% of the sodium replaced, and with significant amounts of the “good guys” added). The Finnish experience doesn’t come anywhere near a 4 to 1 ratio — it’s not even up to a 1 to 1 ratio — yet it was enough to reduce strokes and heart attacks by 60% throughout the nation.
The population of Finland is over five million, and this certainly is larger than the number of participants in any of the drug studies. The biggest drug study on hypertension involved only 17,000 people. The fact that this was done in a whole country and they succeeded in getting this salt-substitute used instead of table salt in food processing, in fast food restaurants etc., as well as at home, shows what can be done. It’s simply amazing that few in this country seem to be aware of this even though the information was published in 1996.
Passwater: How about the DASH (Dietary Approaches to Stop Hypertension) diet studies?
Moore: The DASH diet is a step in the right direction, but it doesn’t go far enough. It is very frustrating to me because it is entirely based on empiricism and “group think.” Those responsible for the DASH diet just looked at evidence showing that there is a little bit of help to be derived from potassium, a little bit of help from sodium and so on. They put the DASH diet and clinical studies together without an understanding of the fundamental relationship between sodium and potassium. That is, they didn’t understand the very important point that, because of osmotic equilibrium, the sum of the sodium and potassium inside the cell is very close to constant (within about 2%).
Therefore, it is virtually impossible — not just because of the sodium/potassium exchange pump and all these things in the body which tend to move sodium in one direction and potassium in the other direction, but just because of physical reasons (the laws of physics) — to lower sodium inside the cell without the involvement of potassium. Potassium has such an important role in the body. You can’t lower the sodium without replacing it with potassium. That is the key: there is just no sense in talking about either sodium or potassium alone! This is so awfully important. It is one point that I would love to get across to the medical profession, but up until now most practitioners have failed to get it.
Therefore, the vast majority of those studies that have been done with dietary sodium were very poorly designed, scientifically. They didn’t take into account that this is not a one variable situation. There are two variables that must be taken into account together! The two are linked, and you have to look at them together if you are going to see a pattern.
Passwater: Everyone in clinical studies is trained to look at one variable at a time, no wonder that synergistic effects are missed.
Moore: Not in physics-that’s where my background is.
Passwater: It’s a shame that more biochemists don’t know a little about biophysics.
Moore: In medical school, this idea of trying to change one variable at a time has become a religion. But the only way you can do that is with drugs. You can change an intake of a drug, i. e. one variable, but once you look at what is going on inside the body, you discover that everything is interlinked. Thus, it is impossible to change one variable without all the others also shifting.
Passwater: I call that polypharmacy, and it’s just too complex for the scientific method that people have been trained to use. All the nutrients seem to have interactions, and you just can’t study them individually.
Moore: That’s right. Nutritionists are still talking about sodium requirements. It depends on the potassium levels in the diet, too.
Passwater: It goes on and on. We try to get the message across. Eventually, clinical researchers will design clinical studies to look at more than one variable at a time. In the meantime, I guess we’ll have to put up with some frustration.
Thank you Dr. Moore for chatting with us about potassium-sodium ratios and hypertension. Next month, we’ll be joined by your Salt Solution co-author, Mark McCarty. WF
Part 3: Old News That Bears Repeating
Over the past few issues, we have been talking with the co-authors of The Salt Solution about the ways in which too much salt and not enough potassium in the diet-common for modern processed-food diets-causes an imbalance between sodium (salt) and potassium that affects every cell in the body and can lead to more than 10 different diseases.
A major part of the problem is that salt is a hidden component of much processed food. In fact, processed food accounts for up to 75% of the salt intake in a typical American diet. In general, it can be said, only 15% of salt intake comes from the saltshaker. It is easy to consume an extra teaspoon of salt (about 2,500 mg) from processed food without even being aware of it Another part of the problem is that food processing removes potassium.
In April, Herb Boynton explained how this potassium/ sodium imbalance affects every cell in the body and can lead to a slew of ailments, ranging from hypertension to cataracts and possibly even erectile dysfunction. In June, Dr. Richard Moore elaborated on how the ratio of these nutrients, which he calls the “K Factor,” keeps the arteries under constant constriction, raising the pressure needed to pump blood through them.
In this month’s installment, co-author Mark McCarty tells us about the link between a low K Factor diet and high blood pressure, stroke, osteoporosis, kidney stones, asthma, stomach cancer and ulcers. Mark absconded from the third year of medical school some years ago to devote himself to applied nutrition, a field that he felt was grievously neglected by the medical establishment. For many years, he was research director for Nutrition 21; where Herb Boynton, a co-author of The Salt Solution, was the founder and president. In that setting, they worked together to develop, test, and market some important cutting-edge supplements, most notably organic selenium and chromium picolinate. Mark is currently president of NutriGuard Research, a supplement company he helped to found, and he also holds consulting positions with Pantox Laboratories, Nutrition 21, and Natural Alternatives. To date, he has authored over 100 publications in the refereed biomedical literature, most of which have appeared in the journal Medical Hypotheses.
Passwater: Mark, let’s review some of the more obvious relationships of the sodium-potassium imbalance to overall health. May we begin with high blood pressure?
McCarty: The link between too much dietary salt and high blood pressure certainly is very old news, but the fact that poor potassium nutrition plays an equally important role in the genesis of high blood pressure and stroke, has, until recently, largely been ignored. The ratio of these two nutrients affects the efficiency of the sodium-potassium pumps in all of the cells in the body-including key vascular tissues such as smooth muscle cells and the endothelial inner lining of the blood vessels. These pumps are vigorously effective if one’s diet is high in potassium and low in salt-which is the way that mankind evolved. But if you reverse that ratio, as modern diets typically do, these pumps function less efficiently. This pump failure can impair the ability of the endothelium to release protective nitric oxide-the hormone-like factor that helps to prevent blood clots, keep blood vessels properly dilated, and ward off the inflammatory process of atherosclerosis. Another consequence is that the level of unbound calcium in vascular smooth muscle cells tends to increase, causing these cells to contract, and thus raising blood pressure by increasing the resistance to blood flow.
Passwater: It also is old news that high blood pressure is a major risk factor for stroke. Aren’t there studies that show that stroke risk increases with salt intake?
McCarty: Salt intakes appear to have a greater impact on risk for stroke than on risk for high blood pressure. This finding emerged from a study in which average urinary sodium levels in various regions in Europe were correlated with the average blood pressure and the incidence of stroke in these regions. The correlations between urinary sodium and stroke risk turned out to be much tighter than those between sodium and blood pressure! Likewise, in certain types of rodent, salt intake has a greater impact on the incidence of stroke than on blood pressure. Another important thing to realize is that, although high blood pressure greatly increases risk for a stroke, the majority of Strokes occur in elderly people whose blood pressure is considered to be Anormal.@ The implication of these findings is that, even if one’s blood pressure isn’t notablyelevated on one’s current intake of salt the, salt in one’s diet may nonetheless be increasing one’s stroke risk!
Passwater: How about salt’s effect on osteoporosis?
McCarty: The more salt one eats, the more calcium the body loses in urine. The calcium level of an individual’s blood is tightly regulated because the level of blood calcium has a major impact on the heart’s electrical rhythm and other vital physiological processes. When a lot of salt is eaten, the immediate impact of the resulting urinary loss of calcium is a transient drop in blood calcium that has to be immediately corrected. The hormone that is produced to return the blood calcium to optimal levels, parathyroid hormone, aids the efficiency of calcium absorption from the diet, but it also has the unfortunate effect of leaching calcium from the bone mineral. On the other hand, potassium rich diets are protective in two ways: the increased potassium intake helps the kidneys to excrete salt more efficiently, so that salt can’t promote as much calcium loss in the urine. Plus, if one’s potassium comes from natural foods, the negatively charged organic molecule associated with that potassium can be metabolized to release bicarbonate, which has an alkalinizing flirt on the body that protects bone from the adverse impact of acid-generating proteins. hitting it simply, if you cat a low salt diet that is high in potassium-rich foods anal in moderate in protein, your bone health should benefit greatly.
Passwater: This might also of affect the risk for kidney stones.
McCarty: Yes, the increased amount of calcium excreted in the urine when one eats a salty, potassium-depleted diet means that there is more opportunity for calcium kidney stones to form. Surprisingly, unless the diet is extremely high in calcium, reducing dietary calcium doesn’t have much impact on the amount of calcium in the urine-and a low-calcium diet actually can make matters worse by increasing the intestinal absorption of the dietary compound oxalate.
This may lead to the formation of calcium oxalate kidney stones. One study has determined that people whose diets have low dietary potassium-to-sodium ratios are three times more likely to form kidney stones than those with high potassium-to-sodium ratios.
Passwater: What’s the connection between a poor K Factor (potassium-to-sodium ratio) and asthma?
McCarty: Several scientists have proposed and in some measure confirmed a link between salty diets and asthma; we discuss their findings in The Salt Solution. Salty diets seem to exacerbate asthma primarily in males. Why females seem to be at leis risk in this regard isn’t clear. A recent study shows that salty diets can make exercise-induced asthma worse. There is suggestive evidence that inefficient function of the sodium-potassium pumps can make the bronchial tubes more sensitive to bronchoconstrictors such as those released by exposure to allergens.
Passwater: What about stomach cancer and ulcers?
McCarty: The highest rates of gastric cancer and gastric ulcers are seen in countries where diets are high in heavily salted foods. Heavy salting of foods is practiced to prevent microbial contamination of food in societies that lack refrigeration; salt is not very efficient for this purpose, however, and, as a result, molds or bacteria frequently generate mutagens in salt-preserved food. This isn’t the fault of salt per se, but rather of lack of refrigeration.
On the other hand, there is some reason to believe that high-salt diets can be directly damaging to the stomach lining, that they increase the ability of the bacterium most responsible for gastric diseases-Helicobacter pylori-to colonize the stomach lining and do its dirty work. What is clear is that, when societies gain access to refrigeration, the use of salt preservation goes down and rates of gastric ulcer and gastric cancer plunge. This was true throughout the world during the 20th century. Today, gastric cancer is one of the less common cancers in the U.S., but it was one of our major cancer killers in the 19th century. Unfortunately, there is still a lot of horrible poverty throughout the world, and gastric cancer is second only to lung cancer as the chief cause of cancer mortality worldwide.
Passwater: You discuss other conditions in The Salt Solution, as well as a practical plan to improve one’s dietary K Factor. Some of these links between salt and illness are well-known, but some are new. You have written extensively about your research over the years. What do you offer that is new in The Salt Solution?
McCarty: I think perhaps the most interesting novel contribution I made to the book deals with senile dementia and the rarity of this disorder among the indigenous people of the tiny island of Kitava of f the coast of Papua New Guinea. 1 encountered the work of Dr. Staffan Lindeberg in the process of doing library research for the book. Dr. Lindeberg is a Swedish cardiologist who has a considerable interest in preventive medicine. He has an avid interest in the impact of dietary factors on health and on the relative immunity of certain third-world peoples to many of the diseases that are prominent killers in Western society. In particular, he has long been interested in the association between dietary salt and hypertension. It is well-documented that all peoples whose traditional diets have not included added salt are essentially immune to essential hypertension. I don’t know of any exception to this generalization.
Passwater: How about vegetarian diets?
McCarty: Vegetarian diets-especially if they feature potassium-rich whole foods-often tend to decrease blood pressure for a variety of reasons. If they are heavily salted, however, they don’t provide absolute protection from hypertension. For example, people in rural China typically eat a quasi-vegetarian diet, but are highly susceptible to stroke and hypertension because their diet has an outrageous salt-to-potassium ratio. The fact that white rice is a very lousy source of potassium doesn’t help. They get about three times as much sodium as potassium. I think that as they incorporate more fatty meats and become overweight, the problem is likely to get worse.
I certainly am in favor of a vegetarian diet. I am a vegan myself, because I think that that’s the type of diet that will provide the best overall health protection. However, a vegan diet is not inherently low in salt, so I have to make a special effort to keep my salt intake relatively low. A lot of vegetarians make up for the lack of animal products and grease in their diet with an increased intake of salty condiments. This is a big mistake; they may just be exchanging a Western way of premature death-heart attack-for an Eastern way-stroke! A lot of health-food-store products that brag about how organic and vegetarian and low in fat they are, are awash in salt. There is just too little awareness on this crucial point-which is why we needed to write our book.
Passwater: Mark, thanks for going over some of this with us. I think we are now in a better position to appreciate your new data on how a sodium-potassium imbalance may be implicated in the development of senile dementia and even, possibly, Alzheimer’s disease. In our next issue we’ll return with you and go into more detail on this novel insight. WF
Part 4: Potassium, Sodium and Dementia
This segment concludes our four-part interview with the three authors of The Salt Solution a landmark book that outlines what is perhaps the greatest danger in the American diet – too much salt and too little potassium.
In this month’s installment, co-author Mark McCarty tells us about the link between a low K Factor diet and dementia. As you may recall, Mark was a medical school “dropout” some years ago, who then devoted his career to applied nutrition. He has long been a colleague of Herb Boynton, the founder of Nutrition 21 and another of the co-authors (along with Richard D. Moore, M.D., Ph.D.) on The Salt Solution. Mark is currently president of NutriGuard Research, a supplement company he helped to found, and he also holds consulting positions with Pantox Laboratories, Nutrition 21 and Natural Alternatives. To date, he has authored over 100 publications in the refereed biomedical literature, most of which have appeared in the journal Medical Hypotheses.
Passwater: In the July issue, we left off with a discussion of Dr. Staffan Lindeberg and some fascinating discoveries he made about the indigenous people of the tiny island of Kitava off the coast of Papua New Guinea. Specifically, you said that he claimed to have found no evidence of senile dementia among this population. May we get back to Dr. Lindeberg and his discoveries?
McCarty: Sure. Naturally, Dr. Lindeberg is fully aware of the evidence that essential hypertension, as well as the age-related rise of blood pressure, are virtually absent in low-salt societies. But he thought it would be interesting to see whether he could carry this inquiry further and determine whether avoiding salt and hypertension would have a correspondingly favorable impact on risk for stroke. Actually, some recent epidemiology suggests that salt intakes have a more impressive impact on stroke risk than on hypertension risk or on blood pressure. In other words, salt increases your risk for stroke in ways that have nothing to do with blood pressure-implying that a salty diet may be dangerous for one’s cerebrovascular health even when blood pressure is considered normal. And everyone should be aware that, whereas high blood pressure can greatly increase the risk of a stroke, the majority of elderly people who have strokes in fact have “normal” blood pressure!
Dr. Lindeberg became aware of an island off the coast of Papua New Guinea called Kitava where the residents have never added refined salt to their food. In fact, there are very few aspects of Western civilization that have caught on there with the exception of tobacco smoking. Most of the adults are tobacco addicts, and they import cigarettes from the West. But aside from that, they incorporate Western foods only to a trivial extent and, in particular, they have never imported salt or added refined salt to foods. They do cook in seawater to some extent, so that their diet is by no means salt-free, but Dr. Lindeberg was able to estimate that they probably don’t get much more than 1,000 mg of sodium a day, which means their salt intake is probably about a quarter of what it averages among people in the United States.
Dr. Lindeberg realized that Kitava offered us a priceless-and probably fleeting-opportunity to examine the impact of unsalted diets on risk for stroke and other vascular disorders. So he organized a Swedish scientific expedition to Kitava and spent a number of months getting to know the Kitavan people and conducting extensive clinical examinations in an effort to determine what proportion of elderly Kitavans had suffered a stroke or had heart disease. ‘There are about 2,500 people on the island, a fair percentage of whom are over 70, so he had plenty of people to examine. Lindeberg had an excellent translator with him, and the Kitavans were very helpful and articulate. But they initially were wary about the drawing of blood. One of the big heroes of the whole project was a very old Kitavan man who, after having his blood drawn, walked around the whole rim of the island just to demonstrate to his colleagues that blood drawing doesn’t harm you!
Dr. Lindeberg conducted physical examinations on a large number of elderly Kitavans, with the intent of eliciting any evidence that they may previously have suffered a stroke or heart attack, or had coronary heart disease. But he also supplemented this information by asking the whole tribe whether they were aware of any person in the tribe who had experienced symptoms suggestive of a heart attack or stroke. The bottom line is that he was unable to unearth any evidence that anyone on the island had ever suffered a stroke or heart attack! Obviously, he wasn’t able to completely rule out that possibility, but it was quite clear that if these disorders existed at all on Kitava, they were extremely rare. The closest he came to a suggestive episode was a story he heard independently from several different people about a man in his 70’s who was walking on the beach and fell over dead for no apparent reason.
This incident occurred in the late 19th century! This should give you an idea of how well the Kitavans hang on to their history! In any case, Lindeberg was completely successful in confirming his suspicion that lifelong consumption of a low-salt diet confers almost total immunity from stroke. Back during the early 20th century, there were reports that stroke was extremely rare among black Africans whose diets were low in salt and who seemed immune to high blood pressure-but Lindeberg’s study provides even more convincing documentation of this point.
Passwater: Please tell us more about their diet.
McCarty: It is quite interesting. They get the majority of their calories from tropical tubers, namely yams and sweet potatoes, which are of low caloric density and extremely high in potassium per calorie. They have no cereal products in their diet, except for a bit of corn in the autumn. Grain products, even whole grain products, usually are not very high in potassium. Fruit, coconuts, greens, wild beans, and a small amount of fish-about 5% of calories-round out their diet, which thus is “pesco-vegetarian.” I have estimated, based on the food consumption data that Dr. Lindeberg published, that these people are getting around 8,000 mg of potassium a day, which is about triple what we get in the United States. All in all, I think their potassium-to-sodium ratio is about 12 times higher than ours, so that is a very major shift-virtually replicating a Paleolithic level of potassium and salt intake.
One interesting aspect of the Kitavans’ diet is that it contains a fair amount of saturated fat. In fact, about 18% of their calories come from saturated fat because they eat a lot of coconuts. However, their diet also provides a meaningful amount of protective omega-3 fats owing to their fish intake, whereas their omega-6 intake is quite low, inasmuch as their diet is quite low in grain products. So the omega-3/omega-6 balance favors omega-3. Another factor likely to be relevant to their excellent vascular health is that they are greyhound-lean throughout life. Their body mass index (BMI) is around 20 to 21, and their insulin levels actually decrease as a function of age, which is, of course, the inverse of what we see in the West. This implies excellent insulin-sensitivity. In fact, not a hint of diabetes is seen among these people.
Passwater: The BMI is an individual’s body weight in kilograms divided by his/her height in meters squared. A BMI of 25 is considered overweight and a BMI of 30 is considered obese.
McCarty: I think the main things the Kitavans have going for them from the standpoint of vascular health are lifelong leanness, insulin-sensitivity, a meaningful amount of omega-3 in their diet, and a whole-food, near-vegan diet that has a remarkably high potassium-to-sodium ratio. In addition, Dr. Lindeberg found that their blood contained a low level of the clot-promotion factor called PAI-1. He noted that this particular component was only about half as high in Kitavans as in Swedes. It would seem that their excellent insulin sensitivity contributes to this, but it also is possible that the Kitavans have some genetic advantage in this regard. You have to balance these protective factors against the fact that they have a high saturated fat intake, As a result, their blood cholesterol levels are not notably low. I recall that they average about 180 in the men and 220 in the women. Also, about 80% of the adults are tobacco addicts. You can bet that the coronary care units in the U.S. are filled with people who smoke and have cholesterol levels in the 180-220 range- yet the Kitavans display no sign of heart disease at all!
Passwater: That is so intriguing. And, of course, Lindeberg also had been unable to find any evidence of stroke among these people.
McCarty: Quite right! This is particularly interesting when compared to the experience in many other Third World cultures, where heart attack has been rare, but stroke usually is quite common. Meanwhile, a careful reading of one of Dr. Lindeberg’s papers brought up a point that I found of exceptional interest. He devoted just a couple of sentences to the observation that he saw no evidence of senile dementia on Kitava, and that all the elderly seemed to be mentally well-preserved.
Passwater: Let me first clarify a point. We haven’t spoken of life span. Is there a significant number of elderly Kitavans?
McCarty: Yes. Proportionally, there are many people in their 70s, 80s and even a few in their 90s.
Passwater: I just wanted to make sure that none of the readers draws the conclusion that Kitavans all die relatively young. If they did, that would, of course, cut down the chances of developing strokes or dementia
McCarty: There is a misimpression that, because the average life span in a lot of Third World countries may be relatively low compared to ours, there would be a paucity of elderly people in these societies. In fact, the average diet confers almost total immunity life span usually is skewed by infant or childhood mortality. I recall call reading that the average 40-year old Bolivian Indian with virtually no access to medical care has a longer life expectancy than a 40-year old resident of the U.S. In other words, if people in these cultures manage to make it through infancy and childhood without succumbing to infection, they have quite a decent chance to become elderly.
The chief causes of death in Kitava are infection and trauma. Also, there are a few very elderly Kitavans who have died in their sleep for no apparent reason, without symptoms suggestive of a heart attack or stroke. Perhaps their aging heart muscles just wore out and they had an arrhythmia. Aside from ovarian cancer-10 cases of which have been documented-cancer seems to be rare (although without autopsies, it is difficult to be sure). There is only one known case of a breast cancer that eroded the overlying skin. The fact that the Kitavan diet consists of low-glycemic index whole foods, and is vegan aside from a modest intake of fish that provides cancer-preventive omega-3, suggests that they should be at low risk for cancer-in part because this diet keeps them very lean and insulin-sensitive. The only fatality that occurred while Dr. Lindeberg was there was that of a 70-year-old man who fell out of a palm tree. We don’t have too many 70-year-old people in the U.S. shinnying up to the tops of palm trees, but I suppose if we did, we would have a fair number of palm tree fatalities!
May I make one other comment about Kitava? It is rather peculiar that these people do not have low cholesterol levels, and most of them smoke-yet there is zero evidence of coronary heart disease in Kitava! That suggests to me that if you eat an unsalted diet and stay lean and insulin-sensitive all your life, this may have a profoundly protective impact that overrides the impact of LDL cholesterol and even smoking. Perhaps salted diets are a permissive factor for heart disease. Do we know of any society eating an unsalted diet that has a significant incidence of coronary disease? I am not sure we do. Of course, the problem is that, as people adopt Westernized diets, salt consumption goes hand in hand with all of the other poor dietary habits that promote vascular disease. I’m not aware of any Third World society that adopted diets high in fatty animal products and refined grains, that didn’t simultaneously become addicted to salt. So we can’t tell whether avoiding salt would have protected them from the other aspects of this diet. The Kitavans are unique in that their relatively high cholesterol levels stem from the use of coconuts, not from any fatty animal products.
Passwater: How about the physical activity of these people? I know they are not couch potatoes, but, I would assume, neither are they marathon runners.
McCarty: Not at all. They probably would laugh at us for doing aerobic exercise. Obviously, there is a certain effort involved in gathering their food, but the impression that I get from Dr. Lindeberg’s work is that while they are probably somewhat more active than the average American, they may get less exertion than a lot of blue collar workers in the U.S. They certainly are not the Oceanic equivalent of the Tarahumara Indians of Mexico (who tend to view marathons as sprints!). Clearly, exercise is not the chief reason why the Kitavans have superb vascular health.
Passwater: In any case-getting back to your comment about dementia-I think there is a sufficient number of elderly people in Kitava to judge whether senile dementia or heart disease would be a significant problem.
McCarty: Yes. And you don’t need to have vast numbers of elderly to encounter dementia. I think I’ve read that about half of Americans over 85 suffer from dementia!
Passwater. That is scary.
McCarty: You bet it is. What’s the point of taking elaborate measures to try to stay healthy into old age if your only reward is to live your last days in a totally dependent state of imbecility? It’s so incredibly important to figure out how to prevent this outcome!
As I was saying, I was fascinated by the brief comment in Dr. Lindeberg’s paper about dementia, and so I got his email address and wrote to him. I asked, “When you say you didn’t see evidence for senile dementia, did this mean that you yourself didn’t encounter any demented elderly people-or did you make some efforts to determine whether anybody on the island had ever heard of anyone who had become senile as a function of age?” He indicated it was the latter. He had attempted to determine whether anybody on the island had known about anyone else on the island who had become demented when they became old-and he learned that senile dementia was a totally foreign concept to the Kitavans!
Full-blown senile dementia in general is not a subtle disease. If a person cannot recognize his own children or the other members of his tribe, you would think that everybody would know that. Bear in mind that in Kitava, no one is distracted by a lot of information overload as we are in modern civilization. There, everyone’s chief concern is about the other members of the tribe. That is what everyone knows more about than anything else. So, if a member of the tribe were to become severely demented, one would think that everyone would know about it. The bottom line is that no one in Kitava had ever heard of an elderly person becoming demented with age-which is quite a striking observation on an island which has about 2,500 residents and a fair proportion of the elderly, and where people can tell you about medical events that transpired a century ago!
I might add that, in response to his inquiries, the Kitavans introduced Lindeberg to a couple of mentally retarded people who were relatively young. This is not germane to senile dementia, but it shows that the Kitavans were trying to cooperate with his investigation.
When I learned about the evident rarity of dementia in Kitava, it jogged something in my memory, and I plowed back into the writings of Dr. Hugh Trowell. Dr. Trowell was a brilliant physician who worked in British East Africa during the middle decades of the 20th century. He wrote several books and monographs documenting the rarity of many “Western” diseases in Africa during the early decades of that century, when well trained British physicians had begun to serve the populace, but Western eating habits were only beginning to catch on among black Africans. Several of his later books were written in collaboration with Dr. Denis Burkitt. Many of our readers will remember them as the Burkitt and Trowell who popularized the health benefits of high-fiber diets.
In any case, my old friend and mentor Herb Boynton loaned me several of Dr. Trowell’s books-large portions of which I had read some years previously and I scanned their indexes for “senile dementia.” I thus found a relevant passage in which Dr. Trowell cited the work of a British psychiatrist who had been practicing at the psychiatric ward of a Nairobi hospital back in the 1930s. From other portions of Dr. Trowell’s book, I had learned that salt use was still uncommon among all but the most socially exalted black East Africans at the time. Further, I learned that stroke was considered extremely rare-rather like the situation that still prevails in Kitava. This psychiatrist wrote that on his psychiatric ward, he observed the full spectrum of psychiatric disorders that one would expect to encounter in Britain or the U.S.-with the exception that “senile dementia was a notable absentee.”
So here, again, we have the correlation between a virtually unsalted diet, a virtual absence of stroke, and a virtual absence of senile dementia!
I am emboldened to suggest that if one keeps his or her cerebral vasculature so healthy as to be virtually immune from stroke, that individual also will be nearly immune from senile dementia-not just the so-called vascular dementia that results from small strokes, but from Alzheimer’s disease as well. In effect, I am proposing that senile dementia is a disease of civilization made possible by salted diets!
Passwater: Tell us more about why you believe that this is the case.
McCarty: There is a lot of epidemiological evidence indicating that risk factors for stroke are very similar to risk factors for Alzheimer’s. I am not the only scientist to have suggested that a healthy cerebrovascular endothelium may act in various ways to prevent the chronic inflammatory process that manifests as Alzheimer’s disease, or to protect neurons from this process. One possibility, supported by some evidence, is that small strokes somehow act as a co-factor that makes Alzheimer’s possible. If this is so, then preventing strokes also would tend to prevent Alzheimer’s. Conversely, it is conceivable that vigorous cerebral blood flow is somehow protective.
Another possibility that I particularly like is that the nitric oxide produced by a healthy microvascular endothelium may have an anti-inflammatory impact on the brain -much as it does in preventing atherosclerosis in large arteries. Bear in mind that both Alzheimer’s and atherosclerosis are low-grade chronic inflammatory disorders.
Additionally, in moderate physiological concentrations, nitric oxide might act to protect neurons from the pro-inflammatory factors that damage and kill them in Alzheimer’s disease. Conversely, it is now known that the toxic amyloid peptides that seem to induce much of the neural damage in Alzheimer’s, also attack the cerebrovascular endothelium and effectively block its production of nitric oxide. This suggests that, once the inflammatory process of Alzheimer’s disease gains a firm foothold, there may be no going back, because the cerebrovascular endothelium won’t be able to recover its healthful protective function. This further suggests that some measures which help to prevent Alzheimer’s may not be of much use for treating it. In other words, don’t wait until the horse is already out of the barn before shutting the barn door!
I probably should mention that some scientists speculate that excess nitric oxide production contributes to inflammatory damage in Alzheimer’s-and I’m not sure they’re wrong! You need to take a subtle look at this issue. In the modest concentrations produced by the healthy vasculature, and in the relative absence of the free radical superoxide, nitric oxide appears to have a number of protective properties, including an anti-inflammatory effect. On the other hand, in many inflammatory disorders, certain immune cells generate large amounts of nitric oxide in conjunction with large amounts of superoxide. These two compounds interact rapidly in a reaction that destroys the nitric oxide and converts it to a really vicious chemical known as peroxynitrite. So whether nitric oxide is helpful or harmful really depends on the context.
In any event, in light of my speculation that vascular nitric oxide might help to prevent dementia, I was particularly intrigued to encounter recent reports that people who use statin drugs to control their cholesterol levels appear to be at greatly reduced risk for Alzheimer’s. A remarkable 70% reduction in risk has been suggested by two studies. Here is the relevance: there is now a lot of evidence that statin therapy lowers stroke risk fairly markedly. This initially seemed a little odd, because LDL cholesterol does not appear to be a strong risk factor for stroke. However, recent studies show that statins can act directly on the vascular endothelium to boost endothelial production of nitric oxide! Actually, there is both an increase in nitric oxide synthesis and a suppression of superoxide production.
As I just stated, superoxide is a potent free radical that can destroy nitric oxide, converting it to dangerous peroxynitrite. Increased effective production of nitric oxide offers a satisfying explanation for the ability of statins to prevent stroke but I suggest that this also may be the mechanism whereby they prevent Alzheimer’s as well. Of course, I can’t rule out the possibility that statins have some direct protective impact on brain tissue, but at least these findings are quite consistent with the possibility that the nitric oxide produced by healthy endothelium helps to prevent dementia.
Another measure which has been shown to boost the ability of vascular endothelium to produce nitric oxide is estrogen. This finding fits very nicely with the fact that there is considerable epidemiological evidence that women who use long-term postmenopausal estrogen replacement are at substantially lower risk for Alzheimer’s!
However, the overriding determinant of cerebrovascular health may be dietary salt and potassium status. In other words, if you eat an unsalted, potassium-rich diet throughout life, chances are that you will have a healthy cerebral vasculature into ripe old age, and this will help you prevent not only stroke but, most likely, Alzheimer’s disease. I realize that this is such an audacious proposition, it probably will be many years before we know just how accurate it is. It may be that the leanness and insulin-sensitivity of the Kitavans contribute importantly to their protection, too-as well as their intake of omega-3. Omega-3 has anti-inflammatory properties, and Alzheimer’s is a type of inflammation.
Passwater: For the readers who may not have read part one of this series of columns, let’s talk about why a potassium-rich sodium-reduced diet would result in the healthy endothelium that you were just speaking of.
McCarty: There is experimental evidence from laboratory rat studies that, in fact, salted diets tend to impair vascular nitric oxide production. Conversely, we know from rabbit studies that a modest increase in blood potassium levels-as can be achieved by eating more potassium tends to aid endothelial nitric oxide function by suppressing endothelial superoxide generation. This is much like what the statin drugs recently have been shown to do. One of the major determinants of these effects is the membrane potential of the vascular endothelial cells. When the membrane potential of endothelial cells is high, this tends to promote nitric oxide synthesis by boosting calcium uptake by the cells, while at the same time inhibiting the mechanisms that generate superoxide. More synthesis of nitric oxide and less of superoxide translates into a considerable boos in the protective activity of nitric oxide.
Passwater: But I thought that an increase in membrane potential helped to keep calcium out of cells!
McCarty: That is true in vascular smooth muscle and many other tissues but you see precisely the opposite effect in endothelial cells, for reasons that are a little too complex to discuss here. In endothelial cells, an increase in intracellular calcium levels is the signal that turns on nitric oxide production.
In any case, the salt and potassium contents of your diet influence the membrane potential of vascular endothelium and other cells by regulating the activity of the sodium-potassium pumps we mentioned earlier. When these pumps are vigorously active, membrane potential tends to increase, whereas you see the opposite effect if they are inhibited. A salted diet in susceptible people causes the body to make inhibitors of these pumps. This in turn helps the kidneys rid the body of excess salt, but at the cost of inhibiting the sodium-potassium pump in many other tissues.
Conversely, an increase in blood potassium levels directly stimulates the activity of these pumps- while helping the kidney to harmlessly rid the body of salt. The net effect is that membrane potentials tend to be high if one eats a low salt, high-potassium diet, whereas they are more likely to be low in the context of a salty, potassium-depleted diet. In torn, with a high membrane potential, the ability of nitric oxide to ward off blood clots, lower blood pressure, and quell inflammation and atherosclerosis is optimized, whereas a low membrane potential means that these benefits are substantially lost.
Note that the modulating effects of salt and potassium on cerebrovascular endothelial function don’t necessarily correlate with blood pressure. In other words, if a salted diet doesn’t raise an individual’s blood pressure, that doesn’t necessarily mean that it isn’t impairing the healthful function of the cerebral circulation and increasing the risk for stroke. Conversely, getting more dietary potassium may protect one’s brain even when it doesn’t evidently improve his or her blood pressure.
By the way, one reason I think that leanness and excellent insulin-sensitivity might play a role in the protection from stroke and dementia enjoyed by the Kitavans is that the excessive fat exposure involved in insulin resistance syndrome can impair vascular nitric oxide function. This correlates nicely with the fact that insulin resistance syndrome increases risk for stroke.
I recently published a technical paper proposing that the key to avoiding strokes is to optimize the nitric oxide production of the cerebrovascular endothelium. I suspect that more and more factors that protect us from stroke-like statins, estrogen, a low-salt/high-potassium diet, leanness, and exercise-are going to be shown to have a favorable effect in this regard.
I also should mention that exercise training can boost endothelial nitric oxide production-as well as reduce stroke risk-while elevated homocysteine, associated with increased risk for both stroke and Alzheimer’s, can impair endothelial function. There is a definite pattern here!
Passwater: One final question about the Kitavans. How can you be sure that these islanders don’t just have some marvelous genetic inheritance that protects them from stroke and dementia? Could you be over-interpreting one rather anomalous observation?
McCarty: I can’t know for sure, but I doubt that good genes alone are primarily responsible. Dr. Lindeberg met one Kitavan who had left the island as a young man and had lived a more Westernized lifestyle for a number of years. This individual, it turned out was both fat and hypertensive! Scientists repeatedly have noted that Oceanic cultures tend to be lean and relatively free of “Western” diseases while they maintain their traditional lifestyles, but that they rapidly become susceptible to obesity, hypertension, diabetes, and vascular disorders when they adopt a Westernized diet. Indeed, some of these cultures prove to be much more susceptible to these disorders than EuroAmericans are-particularly diabetes. The other reason I doubt it’s purely a genetic issue is the admittedly thin evidence that senile dementia was very rare in Kenyans when they also were eating unsalted diets and were virtually free of hypertension and stroke.
I readily admit that my proposal that Alzheimer’s may be substantially preventable by simple natural nutritional measures seems audacious, and this certainly will not be an easy proposition to prove. But my view is that you have nothing to lose by trying this strategy. Eating and exercising in a way that will keep blood pressure low and minimize risk for stroke, may or may not prevent Alzheimer’s. But preventing stroke, vascular dementia, and other potentially devastating consequences of hypertension is no small benefit in itself! And the recent revelations about the apparent ability of statins, estrogen, and aspirin-like drugs (NSAIDS) to reduce Alzheimer’s risk encourage the view that this disorder is indeed highly susceptible to prevention. If drugs have a protective effect, should we expect less of optimal nutrition?
By the way, I should note, in concluding, that Dr. Lindeberg has been very gracious and helpful to me, and I am particularly grateful for the fact that he sent me a copy of his fascinating Ph.D. thesis summarizing his research on Kitava. I hope that someday he will find the time to write his own book describing his experiences there.
Passwater: We thank you, and your co-authors, for bringing out this information about the importance of the dietary K Factor-the potassium-to-sodium ratio in the diet. You are making a significant contribution to overall health, as well as to the reduction of risk factors for the specific diseases that we have discussed. As I said at the start of this series, The Salt Solution is “must” reading for everyone. The book not only presents the scientific evidence, but provides a practical, easy-to-follow, nine-step nutritional program to improve eating habits and reverse the effects of typical high-salt diets. WF