Does diet provide adequate amounts of calcium, iron, magnesium, and zinc in a well-educated adult population?

Standard advice from dietitians, nutritionists, and physicians is that if one eats a well-balanced diet containing a variety of foods, supplements are not necessary. Little information is available, especially in those over 75, to determine whether actual diets do provide adequate amounts of these minerals. The participants of the Baltimore Longitudinal Study of Aging provide seven-day records which include vitamin and mineral supplement intakes. Median daily dietary intakes from diet in all 564 subjects and from diet plus supplements in those who use them were analyzed by age group and gender. More women than men took supplements. Median intakes of calcium from diet were below the recommended dietary allowance (RDA) for unsupplemented women and for supplemented women over 60. Approximately 25% of women under 50 and 10% of women over 50 consumed less than two thirds of the RDA for iron from diet. For both men and women, all groups had median diet intakes below the RDA for magnesium. Forty percent of men and about half of women consumed less than two thirds of the RDA. These results indicate that many people in this well-educated, presumably well-nourished population did not consume adequate amounts of calcium, iron, magnesium, and zinc from diet. More women than men are at risk. Even those taking supplements did not consume adequate levels of some minerals.