New Recommendations for Iron and Zinc.

The Institute of Medicine recently released new recommendations (Recommended Dietary Allowances or RDAs) for a number of vitamins and minerals, including iron and zinc. These minerals are especially noteworthy because special mention was made of vegetarian needs for these nutrients. These recommendations take the place of the RDAs for these nutrients that were last updated in 1989.

While vegetarians often have iron intakes that are similar to non-vegetarians, less of the iron is absorbed from a vegetarian diet. This is because iron from plant foods is all in the form of non-heme iron that is not as well absorbed as heme iron, found in meat and fish. The amount of non-heme iron that is absorbed is increased by vitamin C and decreased by phytates (found in dried beans, rice, and grains), calcium, tea, and coffee. This lower absorption of iron from a vegetarian diet can lead to lower levels of ferritin in the blood. Blood ferritin is an indicator of iron stores, so low ferritin levels show that little iron is stored for use when need is greater or intake is less.

Based on the lower absorption of iron from a plant-based diet, the Institute of Medicine recommends that vegetarians (except those age birth to 1 year) get 1.8 times more iron than non-vegetarians, as indicated below:

RECOMMENDED DIETARY ALLOWANCE
FOR IRON FOR VEGETARIANS

AGE                         IRON (MG)
1-3 years                   12.6
4-8 years                   18
9-13 years                  14.4
Boys, 14-18 years           19.8
Girls, 14-18 years(*)       27
Men 19-30 years             19.8
Women 19-50 years(**)       32.4
Women, 51 years and older   19.8
Pregnant Women              48.6
Breastfeeding Women         16.2 (18 mg if age 14-18 years)

(*) 20.6 mg if using oral contraceptives

(**) 19.6 mg if using oral contraceptives

While it is possible for many vegetarians to get this much iron from their diets, some vegetarians, namely, young children, teenage girls, women, and especially pregnant women, may need iron supplements. Good sources of iron for vegetarians include dried beans, soy products, vegetables like kale and turnip greens, and whole and enriched grains.

Zinc is also less well absorbed from plant-based diets, especially those based on whole grains and dried beans. Because of this, zinc requirements may be as much as 50 percent higher for some vegetarians, according to the Institute of Medicine. However, the committee that creates the RDAs did not feel there was enough evidence to make a separate RDA for vegetarians. Vegetarians should be aware of good sources of zinc like legumes, wheat germ, fortified cereals, nuts, and tofu.

Food and Nutrition Board. 2000. Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academy Press. <www.nas.edu>