Lack of a recommended dietary allowance for copper may be hazardous to your health

The 10th edition of Recommended Dietary Allowances (RDA) did not include an RDA for copper; rather a safe and adequate daily intake was suggested. Criteria, history and uses of RDAs were summarized along with data on dietary intakes, balance and depletion experiments, low (fats and oils, skim milk and yogurt) and high (legumes, mushrooms, nuts and seeds) copper foods and hazards of zinc supplements. Bone disease and cardiovascular disease from diets low in copper have been studied in animals for decades. Men and women fed diets close to 1 mg of copper per day, amounts quite frequent in the US, responded similarly to deficient animals with reversible, potentially harmful changes in blood pressure control, cholesterol and glucose metabolism, and electrocardiograms. Women supplemented with trace elements including copper experienced beneficial effects on bone density. These data exceed similar data on magnesium, selenium and zinc and are sufficient for establishing an RDA. Ischemic heart disease and osteoporosis are likely consequences of diets low in copper. Numerous anatomical, chemical and physiological similarities between animals deficient in copper and people with ischemic heart disease have been noticed. Association between osteoporosis and low copper status deserves further inquiry. Augmenting low copper diets with high copper foods may be beneficial. Committees that establish RDAs should return to the traditions of the first nine editions and make recommendations that promote health and nutritional welfare, meet functional needs, prevent disease and promote public welfare.