Effect of a moderate increase in dietary protein on the retention and excretion of Ca, Cu, Fe, Mg, P, and Zn by adult males.

Mineral utilization was studied by metabolic balance techniques in 10 healthy male volunteers fed diets containing 65 and 94 g protein. Both diets contained approximately 650 mg calcium, 1 mg copper, 16 mg iron, 250 mg magnesium 1000 mg phosphorus, and 7 mg zinc. The diet consisted of conventional foods; the additional 29 g protein was egg white protein mixed into a beverage and fed twice per day. Plasma mineral levels were not affected by the increase in dietary protein. When the diet provided 94 g of protein, urinary calcium and zinc were slightly, but significantly, increased by an average of 35 mg (p less than 0.05) and 0.15 mg (p less than 0.001), respectively. Apparent mineral absorption and balance were unchanged by this modest increase in dietary protein.