[Intestinal protein assimilation and losses in man (author's transl)].

The total quantity of endogenous plus exogenous protein digested and absorbed in the normal gastrointestinal tract in man is in excess of 150 mg per day. Total fecal nitrogen indicates net losses of less than 10% per day in health. Malabsorption and maldigestion both contribute to a decrease in assimilation of exogenous and endogenous proteins. Abnormal serum protein losses across the gastrointestinal tract may be totally recovered if the leak is small and proximal in the intestine. Specific defects in amino acid absorption are often compensated by intact peptide absorption.