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THURSDAY, Sept. 4, 2014 (HealthDay News) -- Could eating foods rich in potassium, such as bananas and potatoes, help lower the risk of stroke and an earlier death for older women?
Possibly, suggest the findings from a new study. But the research is too preliminary to confirm that potassium alone -- and not a better overall diet -- actually plays a major role in helping women avoid strokes and live longer.
However, the study's findings were significant enough for one of the study's co-authors to make this recommendation: "Postmenopausal women should eat more potassium-rich foods, such as fruits, vegetables, beans, milk and unprocessed meats in order to lower their risk of stroke and death," said Sylvia Wassertheil-Smoller, professor emerita with the department of epidemiology & population health at Albert Einstein College of Medicine in New York City.
Potassium is an important mineral that helps the body maintain a balance of fluid and minerals, according to the Academy of Nutrition and Dietetics. It also helps blunt some of the harmful effects of sodium on blood pressure.
Most Americans don't get enough potassium in their diets. A 2012 study led by the U.S. Centers for Disease Control and Prevention found that fewer than 2 percent of American adults surveyed consumed at least the recommended daily amount of potassium -- 4,700 milligrams (mg).
Potassium is found in many foods, according to the U.S. National Library of Medicine and the Academy of Nutrition and Dietetics, such as fruits and vegetables like broccoli, peas, tomatoes, potatoes (especially their skins), prunes, bananas, citrus fruits, strawberries and apricots (especially dried ones). Potassium is also found in milk, yogurt, soy products, nuts, meat and certain kinds of fish, such as halibut and tuna.
People can also get potassium through vitamin supplements, although the new study only looked at potassium consumption through food. "The amount of potassium in a multivitamin supplement is small, and the contribution from supplements to overall potassium intake was minor," Wassertheil-Smoller said. "It is possible that supplements may help women get an adequate amount of potassium in their diet, though we encourage women to eat more natural potassium-rich foods."
In the new study, the researchers tracked more than 90,000 postmenopausal women aged 50 to 79 for an average of 11 years.
The average daily intake of potassium was just over 2,600 mg per day. The lowest potassium group consumed less than 1,925 mg daily. The highest group consumed more than 3,194 mg per day, according to the study.
The researchers found that women who consumed the most potassium were 10 percent less likely to die during the study period and 12 percent less likely to suffer a stroke compared to those who ate the least potassium.
In addition, the investigators found that the risk of ischemic stroke -- that's the type caused by a blockage in a blood vessel in the brain -- was reduced by 16 percent for those who ate the most potassium compared to the least. However, eating more or less potassium didn't affect the risk of hemorrhagic stroke, which occurs when a vessel ruptures.
It's important to note that this study was only designed to show an association between potassium intake and a reduced risk of stroke and earlier death; it was unable to prove that potassium caused these benefits.
But, how might potassium affect stroke risk? "Potassium may play a role in improving blood vessel function in our brains. This could allow better oxygenation of our brain tissue, and prevent tissue death that occurs from lack of oxygen to the brain," explained study lead author Arjun Seth, a medical student at Albert Einstein College of Medicine.
"The effect of potassium consumption on reduced stroke risk could also be due to a better diet overall, though we did not investigate this in our study. We did not look at lipid [cholesterol] levels, which could play a role in stroke risk, though we could not control for these in our study," he said.
The "gold standard" in this kind of research would be to randomly assign some people to eat more potassium and some to eat less and then see what happens. However, a study of this type is "unlikely given the cost and potential lack of compliance over the long run," said Dr. Frank Hu, professor of nutrition and epidemiology at Harvard School of Public Health.
If you're concerned about your risk of stroke, Dr. Larry Goldstein, director of the Duke Stroke Center at Duke University Medical Center, said that people can lower their risk of stroke by 80 percent by avoiding obesity, inactivity, smoking and excessive alcohol consumption.
The study was released online Sept. 4 in advance of print publication in the journal Stroke.
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SOURCES: Sylvia Wassertheil-Smoller, Ph.D., professor emerita, department of epidemiology & population health, and Arjun Seth, medical student, Albert Einstein College of Medicine, New York City; Frank Hu, M.D., Ph.D., professor of nutrition and epidemiology, Harvard School of Public Health, and professor of medicine, Harvard Medical School, Boston; Larry Goldstein, M.D., professor, neurology and chief, division of stroke and vascular neurology and director, Duke Stroke Center, Duke University Medical Center, Durham, N.C.; October 2014, Stroke