CALCIUM-CARBONATE SUPPLEMENTS MAY ADVERSELY AFFECT PROTEIN NUTRITURE

The objective of the project was to determine the effects of level and form of calcium carbonate supplementation of diets on protein status of humans. In study 1, 9 healthy adult subjects were fed a basal diet alone or with graded levels of calcium carbonate. Total calcium intake s were 325, 925, 1525 and 2125 mg/day, respectively, while protein int ake (expressed as nitrogen intake) was kept relatively constant at 8.4 8 g nitrogen/day. As levels of calcium carbonate increased, urinary an d fecal excretions of nitrogen increased and nitrogen balances decreas ed. In study 2, 10 healthy adult humans participated in a 33 day study in which they were fed a basal diet plus added calcium carbonate in s everal commercially available forms. These included a tablet, a carame l, a gum and a wafer (chewable). The wafer form of calcium produced lo wer mean urinary and fecal nitrogen losses, thereby giving a numerical ly higher nitrogen balance. Thus, it would appear that high level calc ium carbonate supplementation of diets of humans may have an adverse e ffect on protein status but that there are only minimal difference amo ng the various forms at least at low levels of calcium intake.