Medical Health Encyclopedia

Certain nutrients interfere with  the body's absorption of dietary iron. They include:

• Polyphenols (found in tea, coffee, red wine, berries, apples).
• Phytates (found in foods such as seeds, dried beans, soy, and bran). Such foods are typically high in fiber. (It is often believed that fiber itself impedes iron absorption, but researchers report that it has little or no effect.)
• Calcium. Calcium impairs the absorption of heme and non-heme iron. However, calcium intake must be quite high to cause any significant problems. For example, a 2002 study reported that cheese had no effect on iron absorption from meals rich in heme and non-heme iron.

Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has lactose intolerance or another reason, such as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the heart and circulatory system, as well as the secretion of essential hormones. There are many ways to supplement calcium, including a growing number of fortified foods.

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Sources of Vitamins B12 and Folate. Vitamins B12 and folate are important for prevention of megaloblastic anemia and good health in general.

• The only natural dietary sources of B12 are animal products, such as meats, dairy products, eggs, and fish (clams and oily fish are very high in B12); like other B vitamins, however, B12 is added to commercial dried cereals. The RDA is 2.4 mcg a day. Deficiencies are rare in young people, although the elderly may have trouble absorbing natural vitamin B12 and require synthetic forms from supplements and fortified foods.

Click the icon to see an image sources of vitamin B12.

• Folate is best found in avocado, bananas, orange juice, cold cereal, asparagus, fruits, green, leafy vegetables, dried beans and peas, and yeast. The synthetic form, folic acid, is now added to commercial grain products. Vitamins are usually made from folic acid, which is about twice as potent as folate. Many experts now recommend that adults have 400 mcg of folic acid daily, which is considerably higher than standard recommendations of 400 mcg of folate, which does not take into consideration the possible benefits of folate on the heart. Women who are trying to conceive, who are pregnant, and who are breastfeeding should take 400 mcg of folic acid.

Click the icon to see an image of sources of folate.