Supplement sleuth

Q: I have anemia and am confused about nonheme versus heme iron supplements. Which type is best absorbed and what are the side effects?

A: Iron is an essential mineral that your body can obtain from three sources:

1. Heme iron is the primary oxygen-carrying component in red blood cells. It also helps muscle cells store oxygen, and is essential to forming ATP (adenosine triphosphate), your body's fuel. Heme iron is found in meats, poultry, pork, shrimp, and sardines.

2. Nonheme iron is obtained from vegetable sources, such as cooked beans, pumpkin seeds, blackstrap molasses, and whole baked potatoes.

3. Supplemental iron is a source that many people rely upon, but not all forms are equally effective. Types include ferrous sulfate and ferrous fumarate (nonheme) and polypeptide (heme).

Heme iron is the most bioavailable form, with a 15-35 percent absorption rate. Conversely, nonheme iron is absorbed at 2-20 percent. Read labels carefully because nonheme is the most common form in supplements.

Constipation, nausea, and bloating are the most frequently reported side effects when taking nonheme iron. Heme iron rarely causes these problems.

Although iron is an essential nutrient, the body cannot excrete excess amounts, which can lead to an overload: Too much iron in the blood gets stored in the liver and heart, causes free radical damage, and is associated with an increased risk for heart disease, diabetes, and cancer. Gary Bushkin, PhD, CNC, a consultant for the natural products industry, specializes in the development of supplements, and functional and natural foods. His books include FAQs: All About Green Food Supplements. Do you have a supplement question? E-mail it to "Supplement Sleuth" at editorial@betternutrition.com.

By Gary Bushkin, PhD, CNC

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