Retention of calcium from various xylitol-calcium combinations in rats

Previous studies have shown that xylitol, the five-carbon sugar alcohol, increases the intestinal absorption of Ca in the rat. In this study an optimum xylitol:Ca molar ratio for Ca absorption and retention was determined in 10-week-old Long-Evans male rats. Xylitol was intubated with 20 mg of 45Ca (as 45CaCl2 or 45CaCO3) into the stomach of fasted rats in 1 ml water using xylitol:Ca molar ratios of 0:1, 0.5:1, 1:1, 1.5:1 or 2:1. Radioactivity of urine, feces and humerus was determined from 48-hr samples. The highest retention rate of 45Ca in the whole body or in the humerus was found when 114 mg of xylitol was given with Ca (xylitol:Ca molar ratio 1.5). Xylitol affected humeral retention more significantly than whole body retention. For comparison, the retention of 45Ca was determined from four lactose:CaCl2 combinations and from Ca-lactate and Ca-citrate salts. None of these combinations increased Ca retention significantly, although lactose at 114 mg dose showed slight positive effect. The results favor the use of a xylitol:Ca molar ratio of 1.5 in Ca supplements.