Effect of resistant and digestible starch on intestinal absorption of calcium, iron, and zinc in infant pigs

The first nonmilk foods that are given to infants contain high levels of starch, a fraction of which is resistant to enzyme hydrolysis. Incomplete digestion of starch may interfere with the absorption of certain minerals. A fraction of dietary starch which is resistant to in vitro enzymatic hydrolysis has been termed resistant starch. The aim of this study was to compare the intestinal apparent absorption of calcium, phosphorus, iron, and zinc in the presence of either resistant or digestible starch. Twelve 7-10- d-old piglets were filled with a T tube inserted into the intestine approximately 3 m distal to the duodenum. Animals received in random order 200 mL of a test meal of cooked, cooled, high amylose corn starch (16.4% resistant starch), or cooked rice starch (digestible starch) administered by an orogastric tube. Both meals contained the same amount of calcium, phosphorus, iron, and zinc. The test meal also contained tracer amounts of ⁵⁹Fe and ⁶⁵Zn, as well as polyethylene glycol 3350, as a nonabsorbable marker. Intestinal apparent absorption of starch was greater after the meal with digestible starch (71.0 ± 17.0%) than after the meal with resistant starch (49.2 ± 10.3) (p < 0.001). After feeding the meals with resistant and digestible starch, mineral apparent absorption was, respectively: calcium, 40.2 ± 11.8% versus 28.1 ± 16.4% (p < 0.05); phosphorus, 73.2 ± 14.0% versus 67.8 ± 18% (NS); iron, 24.1 ± 12.2% versus 12.6 ± 10.6% (p < 0.01), and zinc, 35.0 ± 13.0% versus 30.6 ± 8.22% (NS). In conclusion, a meal containing 16.4% resistant starch resulted in a greater apparent absorption of calcium and iron compared with a completely digestible starch meal. If this finding holds true for the whole bowel, administration of resistant starches could have a positive effect on intestinal calcium and iron absorption.