Suppressive effects of bifidobacteria on lipid peroxidation in the colonicmucosa of iron-overloaded mice

The antioxidative effects of live bifidobacteria on lipid peroxidation in t he colonic mucosa were investigated. Bifidobacterium bifidum strain Yakult, which has been used for production of fermented milk, most effectively inh ibited lipid peroxidation catalyzed by ferrous iron in liposomes among 10 s pecies of bifidobacteria from human intestinal flora. Oral administration o f B. bifidum strain Yakult for 2 wk significantly decreased the level of li pid peroxide (thiobarbituric acid reactive substance) in the colonic mucosa of iron-overload mice (Fe 0.07% in diet). The iron concentrations in plasm a and cecum contents were not affected by administration of B. bifidum stra in Yakult. Bifidobacterium bifidum strain Yakult had no chelating or incorp orating activity for ferrous iron in vitro. Therefore, the antioxidative ef fect of B. bifidum strain Yakult in the colonic mucosa was not thought to b e based on the removal of ferrous iron from the reaction system of lipid pe roxidation. These results suggested that B. bifidum strain Yakult protected the colonic mucosa from oxidative injury without inhibiting iron absorptio n.