In Vivo Effects of Phytic Acid and Polyphenols on the Bioavailability of Polysaccharides and Other Nutrients

The effects of the antinutrients tannic acid, catechin and phytic acid on digestion of starch, protein and lipids, and fiber degradation were studied in rat balance experiments. To separate digestion in the small intestine from fermentation in the hind‐gut, diets were tested without and with the addition of antibiotics. The antinutrients had no effects, either on starch digestion or on fiber fermentation. In contrast, inhibition of protein digestibility was observed with all antinutrients tested, while the digestibility of lipids was reduced only with phytic acid and tannic acid. The fermentability of undigestible protein was affected by tannic acid, whereas that of lipids was affected also by phytic acid.