NATIONAL PANEL ISSUES NEW DIETARY INTAKE RECOMMENDATIONS
- by Dr. Robert C. Martin
If you are the type of person who pays attention to whether you are getting the Recommended Daily Allowance (RDA) of Vitamins and Minerals you now have a new set of recommendations to remember. Recently the National Academies Institute of Medicine released new guidelines for recommended daily dietary levels of vitamins and minerals. The report on Dietary Reference Intakes (DRI) based on extensive research is the first comprehensive review of the RDAs in 20 years.
The full report also recommends adequate intake (AI) levels as well as tolerable upper intake levels (Ul) to help people avoid harm from nutrients.
Vitamin A: Besides being important for normal vision, vitamin A plays a vital role in gene expression, reproduction, embryonic development growth and immune function. To ensure adequate stores of vitamin A in the body, men should consume 900 ug/day and women should consume 700 ug/day. The UL was set at 3,000 ug/day. Recent research shows that excess Vitamin-A intake may increase the risk of physical birth defects, liver abnormalities in adults, and bulging of the skull where bone has not yet formed in infants and young children.
Vitamin-K: This nutrient plays an essential role in the coagulation of blood and is found in green leafy vegetables. An AI of 120 ug/day for men and 90 ug/day for women was determined. No adverse effects have been reported for vitamin K, so a UL was not established.
Chromium: A number of studies have shown that chromium stimulates insulin action in the body. However the daily requirement for chromium could not be established because not enough information exists to determine a relationship between a particular dose of the nutrient and insulin response. Not all studies show that chromium supplementation has a positive effect on the regulation of glucose. An AI of 35 ug/day for men and 25 ug/day for women was recommended.
Copper: The new RDA for copper, a nutrient necessary for proper development of connective tissue (muscles, tendons, ligaments), nerve coverings and skin pigment, is 900 ug/day for both men and women. To protect against possible liver damage, the UL was set at 10 mg/day. Copper is widely distributed in foods such as organ meats, seafood, nuts and seeds. Some foods that are consumed in substantial amounts, such as milk, tea, chicken and potatoes, also contain the nutrient, but at lower levels.
Iodine: Iodine is an important component of thyroid hormones and is stored in the thyroid gland. A deficiency can cause mental retardation, goiter and dwarfism. A RDA of 150 ug/day was established for men and women. Although some plants have iodine the best source is iodized salt.
Iron: Iron is vital for transporting oxygen in the bloodstream and for the prevention of anemia. Even more of the nutrient is needed during periods of growth and for the fetus during pregnancy. Premenopausal women also need more. The report sets the RDA for men and postmenopausal women at 8 mg/day and at 18mg/day for premenopausal women. Pregnant women should consume 27 mg/day which usually requires taking a small supplement since it is difficult to get that much iron through diet alone.
Manganese: This nutrient is involved in bone formation and in protein, fat and carbohydrate metabolism. Nuts, legumes, tea and whole grains are rich sources of manganese. The report sets an adequate intake level for manganese at 2.3 mg/day for men and 1.8 mg/day for women. The UL is 11 mg for adults.
Zinc: Zinc is associated with more than 100 specific enzymes and is vital for protein function and gene expression. Many breakfast cereals are fortified with zinc and it is naturally found in red meats and whole grains. The RDA is 11 mg/day for men and 8 mg/day for women.