June 29, 2009

Some nutrients work better in pairs

Most nutrients don't fly solo -- they can interact, join forces or even cancel each other out -- a U.S. health newsletter reports.

Two of the key nutrient pairs the Harvard Health Letter writers mention are:

-- Vitamin D and calcium. Calcium is easily absorbed, primarily in the small intestine, if large quantities are present but in smaller amounts the mineral gets absorbed with active assistance from vitamin D. Right now, official nutrition guidelines recommend adults get 1,000 mg of calcium and 400 International Units of vitamin D daily. However, some experts say a much higher vitamin D intake -- 1,000 IU daily or more -- is even better.

-- Sodium and potassium. Although sodium is an essential nutrient, most Americans consume far more of it each day than they need, raising their blood pressure and increasing their chances of having a stroke or heart attack.

Potassium counters the harmful cardiovascular effects of a sodium surplus by encouraging the kidneys to excrete sodium. Many studies show a connection between high potassium intake and lower blood pressure and suggest the potassium-to-sodium ratio may be more important than potassium -- or sodium -- alone.