Chromium

Chromium, a mineral, has a role in regulating blood-sugar levels. It can improve insulin sensitivity, which may lower the risk of diabetes and heart disease.

Research suggests that chromium supplements may have an effect on blood-lipid levels, but the results are contradictory. In some studies, chromium supplements ranging from 150 to 1,000 micrograms (mcg) a day lowered total cholesterol, LDL cholesterol, and triglycerides -- and increased apolipoprotein A, a component of HDL cholesterol -- in people with heart disease or elevated blood cholesterol. But other studies found no positive effects on blood-lipid levels.

Chromium is found in small amounts in a variety of foods, including whole grains and lean meats. Recommended adequate intake is 25 mcg for adults under age 50, and 20 mcg for adults age 50 and older. It is estimated that most adults get at least that amount in their diets.

Research is also unclear on whether Vitamin E is effective against heart disease