Potassium, Stroke, & Racial Inequality
Scientists have long known that eating a diet high in potassium is associated with a reduced risk of stroke. The potassium–stroke connection has now been strengthened by a study showing that potassium inhibits the function of blood platelets (Hypertension 2004;44:969–73), an effect that would be expected to protect against stroke.
Stroke is one of the leading causes of death and disability in Western societies. The most common type is caused by a blockage of one of the arteries that supplies oxygen to the brain, usually as a result of hardening of the arteries (atherosclerosis). Risk factors for stroke are similar to those for other types of cardiovascular disease: high blood pressure, elevated cholesterol levels, cigarette smoking, obesity, diabetes, and lack of exercise. Eating more potassium has been shown in both animal and human studies both to lower blood pressure and to reduce stroke risk. The stroke-preventing effect of potassium, however, is not due entirely to its effect on blood pressure, because potassium is beneficial even for people with normal blood pressure.
Blood platelets appear to be a key factor in stroke development. Platelets are blood cells that play a role in normal blood clotting. Through a complex process, platelets can also promote the development of atherosclerosis, especially if they are “overactive,” as they are in some people with heart and blood vessel disease. Drugs that inhibit platelet aggregation, such as aspirin and clopidogrel (Plavix®), are often prescribed by doctors for people who are at high risk of having a stroke.
In the new study, a group of healthy men and women supplemented their usual diet with potassium for three days, in the amount of 2,340 mg per 70 kg (154 pounds) of body weight per day. That amount of potassium is similar to the level in a typical diet. After three days, there was a significant decrease in platelet activity. The effect of the potassium supplement was more pronounced in white people than in black people, and was statistically significant only in whites. The difference in potassium effect between racial groups may have been due to the fact that black participants were somewhat deficient in potassium at the start of the study, and that three days of supplementation were not enough to replenish their potassium stores.
African Americans have particularly high rates of both high blood pressure and stroke, and they also tend to consume less potassium in their diet than whites do. The differences in disease risk among white and black people may be due in part to genetic factors. However, environmental influences are undoubtedly involved as well. The results of the new study suggest that increasing potassium intake (by eating more fruits, vegetables, nuts, and whole grains) may be a simple way to reduce the risk of having a stroke.
Alan R. Gaby, MD, an expert in nutritional therapies, testified to the White House Commission on CAM upon request in December 2001. Dr. Gaby served as a member of the Ad-Hoc Advisory Panel of the National Institutes of Health Office of Alternative Medicine. He is the author of Preventing and Reversing Osteoporosis (Prima, 1994), and co-author of The Natural Pharmacy, 2nd Edition (Healthnotes, Three Rivers Press, 1999), the A–Z Guide to Drug-Herb-Vitamin Interactions (Healthnotes, Three Rivers Press, 1999), Clinical Essentials Volume 1 and 2 (Healthnotes, 2000), and The Patient’s Book of Natural Healing (Prima, 1999). A former professor at Bastyr University of Natural Health Sciences, in Kenmore, WA, where he served as the Endowed Professor of Nutrition, Dr. Gaby is the Chief Medical Editor for Healthnotes, Inc.
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