Calcium supplemental use to meet human calcium requirements

The overall objective of this project was to investigate the effects of consuming several different commercially available calcium supplements. Bioavailability, cost, convenience, physiological responses to each supplement, feasibility and need for a supplement by the targeted population were assessed. Three studies composed the project. The first study consisted of feeding a controlled diet to two groups of ten young adults. Subjects were fed a laboratory controlled diet with one of seven calcium supplements: milk, oyster shell calcium plus vitamin D, calcium lactate and gluconate, mixed calcium source (Mega-Cal), dolomite calcium, or purified calcium carbonate. Calcium carbonate supplementation resulted in the poorest calcium balances and longest fecal transit times while calcium gluconate required the consumption of the largest number of tablets at the highest cost to the consumer. Milk supplementation was fairly expensive, resulted in the highest calcium balance and lower fecal transit time and caused greatest complaints of gastro-intestinal distress. In Study II, seventy-two retired breeder female mice were fed a basal diet plus one of eight calcium supplements (seven described previously and an additional supplement-purified calcium carbonate plus vitamin D). Highest bone breaking strength was noted in the group of mice fed purified calcium carbonate plus vitamin D, but the calcium deficient group also had high bone breaking strength. The mice fed calcium gluconate had the best calcium absorption but mice fed purified calcium carbonate had the most positive calcium balance. In Study III, a survey was conducted to investigate relationship of calcium intake and urinary calcium excretion to other components of the self-selected diets of elderly persons. Only 36% of these elderly subjects consumed 75% or above of the RDA for calcium. Calcium intakes correlated significantly and positively with sodium intakes, phosphorus intakes and protein intakes and tended to correlate (p $\u3c$ 0.101) with ascorbic acid intake. Urinary calcium excretion correlated negatively and significantly with ascorbic acid intake and tended to increase (p $\u3c$ 0.103) with sodium intake