Calcium, magnesium, phosphorus, copper, and manganese balance in adolescent females

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Abstract
Calcium, magnesium, phosphorus, copper, and manganese balances were determined in 14 girls (12.5 to 14.5 years of age) during a 30-day period. Menus were composed of ordinary foods and were typical of subjects' usual dietary habits. The diets contained 1.07 g calcium, 193 mg magnesium, 0.85 g phosphorus, 2.8 mg copper, 3.0 mg manganese, and 7.4 or 13.4 mg zinc daily. Defatted soy was substituted for 0, 15, or 30% of the meat in lunch menus. Neither the alteration of dietary zinc levels or the partial substitution of soy for meat significantly affected retention of the five minerals. Retentions of calcium (r = 0.654), magnesium (r = 0.786), phosphorus (r = 0.560), copper (r = 0.805), and manganese (r = 0.855) by subjects were all significantly (P < 0.001) correlated to retention of zinc. These correlations probably reflect the correlations between fecal losses of calcium (r = 0.438), magnesium (r = 0.434), phosphorus (r = 0.377), copper (r = 0.318), and manganese (r = 0.318) and the volume of feces. On these dietary regimes adolescents were in positive balances for calcium, phosphorus, and copper, but were in negative balances for magnesium and managenese.