29 December 2011
In the interest of heart health, you may virtuously set aside the saltshaker to keep your sodium intake down, knowing that dietary sodium can raise blood pressure in many people. But you may not know that unless you also are careful to keep your potassium intake up, your cardio-protective efforts are likely falling short.
Proof of potassium’s importance: In a recent study published in Archives of Internal Medicine, researchers examined data on 12,267 US adults, analyzing how the ratio of dietary intake of potassium and sodium affected mortality rates. Compared with people who had the most favorable ratio of potassium to sodium consumption (consuming the most potassium and the least sodium), those who consumed the least potassium and the most sodium had a 46% greater risk of dying from any cause… a 46% greater risk of dying from cardiovascular disease… and more than double the risk of dying from ischemic heart disease (narrowing of the blood vessels that supply blood and oxygen to the heart). In addition: A study published in Journal of the American College of Cardiology found that people who ate at least three pieces of potassium-rich fruit daily had a 21% lower risk for stroke than those who consumed less potassium.
How potassium helps: Laura Bellows, PhD, MPH, RD, an assistant professor in the department of food science and human nutrition at Colorado State University in Fort Collins, explained that potassium’s primary contribution to cardiovascular health is tied to its beneficial effects on blood pressure. Potassium helps control blood pressure by promoting the proper balance of fluids in the body… helps offset the adverse effects of dietary sodium… increases the amount of sodium excreted via the urine… and may help prevent the thickening of artery walls.
While adequate potassium intake is particularly vital for people who have blood pressure problems and/or who consume too much sodium, potassium has other positive effects that make it important for everyone. Additional benefits: Potassium facilitates proper nerve function and muscle control… inhibits formation of harmful free radicals… reduces kidney stone risk… may prevent or slow bone loss… and may ease rheumatoid arthritis.
Targets: The average adult needs 4,700 mg of potassium per day (or 5,100 mg per day for breast-feeding women), but many of us fall short. According to the Institute of Medicine, most American women ages 31 to 50 consume no more than half the recommended amount of potassium. In addition, the current generally recommended limit for sodium, according to the government’s Dietary Guidelines for Americans, is 2,300 mg per day—so the ratio of potassium to sodium should be about two-to-one. For people who are over age 50 and those of any age who are African-American or have hypertension, diabetes or chronic kidney disease, the recommended sodium limit is 1,500 mg per day—so the ideal ratio of potassium to sodium is about three-to-one.
Why do so few of us hit these healthy ratios? “Our dietary problems tend to begin with our busy lifestyles and the resulting reliance on packaged and processed foods. We do not take time to prepare and eat the vegetables, fruits and other healthful foods that are major potassium sources,” Dr. Bellows said.
Boosting potassium: Potassium supplements can cause gastrointestinal upset and impair absorption of vitamin B-12—and megadoses can lead to a potentially fatal condition called hyperkalemia, so the best way to get potassium is from food, Dr. Bellows emphasized. Important: Check with your doctor before increasing your potassium intake—people with kidney disease or certain other conditions may need to limit potassium.
The Web site www.ars.usda.gov/services/docs.htm?docid=18877, from the USDA Agricultural Research Service, can help you identify foods rich in specific nutrients. Per the USDA site, some top sources of potassium include…
White beans, 1 cup—1,189 mg
Potato (baked with skin)—1,081 mg
Swiss chard, 1 cup cooked—966 mg
Lima beans, 1 cup—955 mg
Spinach, 1 cup cooked—839 mg
Tomato sauce, 1 cup—811 mg
Papaya, 1 medium—781 mg
Raisins, ½ cup—543 mg
Orange juice, 1 cup—496 mg
Halibut, 3 ounces—490 mg
Tuna, 3 ounces—484 mg
Carrots, 2 raw—460 mg
Banana, 1 medium—422 mg
Milk (nonfat), 1 cup—382 mg
Milk (low-fat), 1 cup—366 mg
Source: Laura Bellows, PhD, MPH, RD, is an assistant professor and extension specialist in the department of food science and human nutrition at Colorado State University in Fort Collins. She has received numerous honors, including a 2011 Presidential Early Career Award for Scientists and Engineers, the highest honor bestowed by the US government on science and engineering professionals in the early stages of their independent research careers.
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