Increased dietary calcium and small bowel resection have opposite effects on colonic cell turnover

Oral supplements of calcium reduce the mitogenic effects of fatty acids and bile acids on large bowel mucosa. The cytokinetic effects of intraluminal calcium were tested in normal and adapting colonic epithelium. Male Sprague-Dawley rats (n = 60) weighting 356.7 +/- 24.9 g were submitted to either an 80 per cent jejuno-ileal resection or simple transection and resuture of the jejunum. Within each group, half the animals had 24 g/l calcium lactate added to the drinking water. Seven weeks postoperatively crypt cell production rate (CCPR) was determined in the lower descending colon. Among controls with transection CCPR was 4.49 cells crypt-1 h-1; calcium supplements reduced this figure by 26 per cent (P less than 0.05). As expected jejuno-ileal resection increased CCPR (by 51-61 per cent), but again calcium reduced this response by 31 per cent (P less than 0.02). Increased dietary levels of calcium thus inhibit colonic cell turnover and blunt the adaptive response to massive enterectomy, conceivably by binding tropic factors such as bile acids.