Vitamin requirements of the elderly.

In general, low dietary intakes can account for much of poor vitamin nutriture reported among various elderly populations. Despite problems in assessing vitamin nutriture in the elderly, the 1980 RDAs for thiamin, riboflavin, and ascorbic acid seem appropriate for those populations. However, RDAs for vitamin A and folate may be too high and the RDAs for vitamin D, vitamin B-6, and vitamin B-12 may be too low, due to specified age-related changes in the metabolism of these vitamins. For vitamin E, vitamin K, niacin, biotin, and pantothenic acid, the data is conflicting and/or insufficient to make a judgment about the appropriateness of the RDAs or to estimate safe and adequate daily intakes for the elderly.