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Potassium-to-Sodium Ratio Affects Overall Health Part 3: Old News That Bears Repeating:
An interview with Mark McCarty
By Richard A. Passwater, Ph.D.
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
© 2001 Whole Foods Magazine and Richard A. Passwater, Ph.D.
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