[Effects of mode of food sterilization on mineral absorption in germ-free and conventional rats].

Minéral balances of P, Ca, Mg, Na, K, Mn, Fe and Cu were determined for three groups of holoxenic rats (CV) fed a non sterilized (CVN), steamsterilized (CVA) or irradiated (CVI) diet and for two groups of axenic (GF) rats fed a steam-sterilized (GFA) or irradiated (GFI) diet. In the group of CV rats as compared to CVN group of rats, the CVA and CVI rats retained less Cu and more Fe and Mn, their urinary excretion of P and Mg was higher and they retained less Mg. Comparison between CV and GF rats showed that the apparent absorption and retention of Ca, P, Mg, Mn, Cu were higher in GF than in CV rats. On the contrary, the apparent absorption of Na and K was lower in GF than in CV rats. However, the observed differences were modified by the mode of diet sterilization. Thus, with respect to the apparent absorption of Na, K, Mn and urinary excretion of Mg, the differences between CV and GF rats were larger when the diet was irradiated than when it was steam-sterilized. On the contrary, the apparent digestibility and urinary excretion of Mg, the apparent absorption and retention of Fe were more modified when the diet was steam-sterilized than when irradiated. For some parameters of the metabolism of Na, K, Fe, Mn, Mg, and P measured in GF rats, the differences observed between GFA and GFI rats were larger than in CV rats. Accordingly, the mode of sterilization is liable to modify the metabolism of some minerals and the microbial flora of the digestive tract is capable of modifying this action.