Effect of Ascorbic Acid and of Orange Juice on Calcium and Phosphorus Metabolism of Women

Abstract

The effects of orange juice and of ascorbic acid on calcium and phosphorus metabolism were investigated using 12 college women as experimental subjects. The study was divided into 9 5-day periods. During the first three periods (basal I), all subjects were on the basal diet which provided a mean of 336 mg calcium, 806 mg phosphorus, and a calculated 22 mg ascorbic acid daily. During the second three periods, for half of the subjects a supplement of 65 gm of orange juice was provided at each meal and for the other subjects, 25 mg crystalline ascorbic acid. During the last three periods, the subjects were again on the unsupplemented basal diet (basal II). For both groups of subjects, calcium absorption was significantly greater during the periods of supplementation than during the basal II periods. Urinary excretion of this element was increased both during the periods of supplementation and the basal II periods which followed when compared with that of the basal I periods. Supplementation of the basal diet with orange juice or crystalline ascorbic acid resulted in calcium retention which was significantly greater than during the succeeding periods when only the basal diet was given. Although the orange juice group absorbed and retained a somewhat greater amount of calcium than did the ascorbic acid group the differences were not statistically significant. Neither orange juice nor ascorbic acid in the amounts given in this study influenced significantly phosphorus utilization by these subjects. Calcium and phosphorus absorption were highly correlated during the basal I periods, but lower coefficients of correlation were obtained during the supplemented and basal II periods. Conversely, during the basal I periods there was a low correlation between calcium and phosphorus retention, which increased when either orange juice or crystalline ascorbic acid was added to the diet, with further increases during the basal II periods.