Meal components including fat, fiber, and carbohydrates can influence the intestinal absorption of calcium; such interactions may be of even greater importance in the presence of intestinal disease. This study compares intestinal absorption of 47CaCl2 administered in four ways: in water, within a standard meal, with a liquid formula (Ensure, Ross Laboratories, Columbus, Ohio), or with a glucose polymer solution (Frodex-15, Ross). Studies were carried out in 9 patients with ileal resection, 3 patients with jejunoileal bypass, and 14 controls. Fractional calcium absorption from water was lower in patients than in controls. Absorption was enhanced 1.5- to 5-fold when 47CaCl2 was administered with a liquid formula diet containing a glucose polymer or with the glucose polymer alone. Patients with the lowest calcium absorption from breakfast showed the greatest effect of calcium ingestion with formula or glucose polymer. These findings further emphasize the importance of meal composition on calcium absorption and provide a possible mechanism for enhancing calcium absorption in some patients with chronically impaired absorption.