Getting more potassium in your diet may help protect you against the most common type of stroke, according to a new Swedish analysis of 10 prior studies. Susanna C. Larsson, PhD, and colleagues at the Karolinska Institute concluded, Dietary potassium intake is inversely associated with risk of stroke, in particular ischemic stroke.
The researchers looked at data from prospective studies, which follow participants over a set number of years, with a total of 8,695 stroke cases and 268,276 participants. They found that for every additional 1,000 milligrams per day of potassium consumed from foods such as fruits, vegetables and dairy, risk of stroke decreased by 11%. That amount of extra potassium is a little more than that found in two bananas (see box).
When researchers pooled the results from five studies that reported results by subtypes of strokes, they also found an 11% lower risk of ischemic strokes. Caused by an interruption of the brains blood supply, ischemic strokes are the most common subtype. There was no apparent benefit against hemorrhagic strokes, which are caused by a ruptured blood vessel in the brain.
Besides combating high blood pressure, researchers speculated, potassium may reduce stroke risk by improving blood-vessel function.
The possibility that other factors may account for the observed association cannot be ruled out, Larsson and colleagues cautioned. For example, foods rich in potassium also contain other nutrients that might contribute to lower stroke risk. The association between potassium and lower stroke risk persisted, however, even when the analysis was restricted to studies that adjusted for other nutrients. The researchers also pointed to a 1998 study that found potassium supplements reduced stroke risk, even after adjusting for hypertension.
These foods are among those that are good sources of potassium:
Sweet potato, 1 baked-694 mg
Tomato paste, 1/4 cup-664 mg
Potato, 1 baked, flesh-610 mg
White beans, canned, 1/2 cup-595 mg
Yogurt, plain, non-fat, 8 oz-579 mg
Prune juice, 3/4 cup-530 mg
Halibut, cooked, 3 oz-490 mg
Soybeans, green, cooked, 1/2 cup-485 mg
Tuna, yellowfin, cooked, 3 oz-484 mg
Lima beans, cooked, 1/2 cup-484 mg
Winter squash, cooked, 1/2 cup-448 mg
Bananas, 1 medium-422 mg
Milk, non-fat, 1 cup-382 mg Making sure you get enough potassium in your diet is important, says Alice H. Lichtenstein, DSc, director of Tufts HNRCA Cardiovascular Nutrition Laboratory. Foods rich in potassium span a wide range of catagories, from vegetables to fish to legumes, she adds. And best of all, they are nutrient dense.
TO LEARN MORE: Stroke, online first at dx.doi.org/10.1161/strokeaha.111.622142. What You Can Do to Prevent a Stroke, Tufts Health & Nutrition Letter Special Report, August 2010.