Calcium carbonate treatment of diarrhoea in intestinal bypass patients

Objective: To study the effect of supplemental calcium carbonate on faecal water, calcium, bile acid and lipid concentration and output in intestinal bypass subjects with diarrhoea. Design: Prospective, single-arm treatment trial of oral calcium carbonate, 2400 or 3600 mg Ca²⁺ per day, given for 12 weeks. Methods: Faecal constituents were determined in wet or lyophilized stool of 24-h collections at baseline and at 12 weeks of study. Calcium was measured by absorption spectrophotometry. Bile acids, long-chain fatty acids and short-chain fatty acids were analysed by gas chromatography. Results: In 15 subjects, calcium supplementation reduced bowel frequency by a mean of 49%, faecal wet weight by a mean of 50% (1292 to 646 g per day), and dry weight by a mean of 36%, P < 0.001. Faecal water concentration was reduced from 76.4 ± 1% to 70.2 ± 2%, P < 0.01. Faecal water concentration was inversely correlated with dry faecal calcium concentration (r = -0.75, P = 0.00001). Conclusion: Calcium reduces the diarrhoea of intestinal bypass patients. It is suggested that the constipating effect of calcium may be related to reduction in faecal water.