Ingestion of raffinose promotes calcium absorption in the large intestine of rats.

We examined the effects of feeding raffinose on intestinal calcium absorption in ovariectomized rats by two separate experiments. In experiment 1, female Sprague-Dawley rats (6 wk old) were divided into two groups: sham operation and ovariectomy, and fed diets with or without raffinose (30 g/kg diet) for 4 wk. In experiment 2, ovariectomized rats with cecocolonectomy or transsection and reanastomosis (sham) were divided into two groups as in experiment 1 and fed the same diets for 3 wk. In experiment 1, calcium absorption was lower in the ovariectomized rats than in the sham rats but calcium absorption in rats fed the raffinose diet was higher than that in rats fed the raffinose-free diet. In experiment 2, increased calcium absorption in the raffinose group was abolished by cecocolonectomy. The impaired absorption in ovariectomized rats was restored by feeding raffinose. The large intestine is involved in the beneficial effects of raffinose.