[The influence of diet on the urinary excretion of total, free and conjugated non-dialysable hydroxyproline in the normal adult (author's transl)].

Having established reference values for the different forms of urinary excretion of hydroxyproline on the basis of the results obtained in 12 normal subjects aged from 20 to 43 years, the authors studied the influence of three diets on the excretion of total, free and conjugated hydroxyproline. Urinary levels of total and peptide dialysable hydroxyprolines were found to be highly sensitive to the dietary collagen content, whilst free hydroxyproline increased only when the dietary collagen intake was very high. Peptide non-dialysable hydroxyproline, corresponding to peptides of molecular weight 6000-8000 was not influenced by diet. The ratio dialysable hydroxyproline/non-dialysable hydroxyproline varied from reference values if the diet was loaded with collagen. Only the ratio free hydroxyproline/non-dialysable hydroxyproline seemed to be independent of diet in the subjects studied.