Council Adding Two Nutrients in Revised Dietary Guidelines

The National Research Council today will release the first revision in nearly a decade of its nutritional guidelines, the Recommended Dietary Allowances, adding two new nutrients and encouraging smokers to get more vitamin C.

The 10th edition of the guideposts for nutritional adequacy, which lists suggested intakes of 11 vitamins and 7 minerals, also urges a greater consumption of calcium-rich foods during the growing years when bone development is at its peak. It increased the RDA for calcium to 1,200 milligrams for adolescents through age 24. The previous average daily intake of 1,200 milligrams was limited to youths under age 18.

The two new nutrients are vitamin K, which is noted for its role in normal blood clotting, and the trace mineral selenium, which may contribute to heart health when in adequate supply.

Because scurvy, the vitamin C deficiency disease, is rarely seen today, the RDA for the vitamin remained unchanged. In its report, to be officially released in Washington, the five-member committee of nutrition experts will, however, advise smokers, who tend to lose some of the vitamin’s protective effects, to increase their consumption of citrus and other vitamin C-rich foods to include an additional 100 milligrams daily.

Based on data gathered in population studies in this country and in Canada, reductions of six nutrients also were established in the 270-page report. They are the major minerals magnesium, zinc and iron and the vitamins B6, B12 and folate (folacin).

Magnesium intake for children dropped 30 milligrams and for women during pregnancy and lactation, the RDA also was lowered. The RDA for zinc, essential for growth, wound healing and vitamin A absorption, declined to 12 milligrams a day for adult women, while the previous RDA of 15 milligrams for adult men remained unchanged. Vegetarians and people avoiding red meat are typically those who suffer from a shortage of zinc.

The iron RDA for adolescent girls and premenopausal women dropped from 18 to 15 milligrams. The committee also reduced the RDA for folate, an important protector against anemia, to 240 micrograms for men ages 25 to 50 years of age and 190 micrograms for women of the same ages. The suggested folate intake for both men and women in the last edition was 400 micrograms both for men and women.

Vitamin B12, also essential to normal blood function and development, dropped a microgram from three a day to two for men and women. The remaining nutrients stayed the same.

Throughout the years, the RDAs have become widely known and applied. They have been used to provide standards by which nutritional adequacy can be assessed, although they are not meant to serve as requirements, according to the committee. Rather, they are based on concept of where the average, healthy person’s intakes should be.

They contain individual recommendations for specified age groups, including infants, males and pregnant and lactating women, not individuals.