EFFECT OF VITAMIN RESTRICTION ON CECAL BACTERIA AND SHORT-CHAIN FATTY-ACID CONCENTRATIONS IN RATS

Food restriction and intestinal bacteria had been reported to have eff ects on the physiological processes of laboratory animals. Therefore, a study was carried out on the effect of vitamin restriction on the ca ecal bacteria and short-chain fatty acid (SCFA) concentrations in Wist ar rats. In rats fed ad libitum with a purified diet with a 0.3 per ce nt vitamin mixture, concentrations of bifidobacteria increased signifi cantly (P<0.05) compared with animals fed a 1 per cent and 2 per cent vitamin diet. There was also a trend of increased lactobacilli, but th is was not significant. Overgrowth of aerobic bacteria such as enterob acteria and enterococci was not found in the 0.3 per cent group. SCFA concentrations were reduced, but not significantly, in the 0.3 per cen t group compared with the 1 per cent and 2 per cent groups. Rats fed a 50 per cent restricted diet containing 1 per cent vitamin mixture had significantly increased concentrations of lactobacilli (P<0.001) and bifidobacteria (P<0.05). In the 2 per cent vitamin regimen only, lacto bacilli increased in the 50 per cent restricted group, but not signifi cantly. Significantly decreased concentrations (P<0.01) of staphylococ ci were found in the animals fed 50 per cent restricted diets compared with the ad libitum groups. SCFA concentrations were reduced (P<0.01) by food restriction with both the 1 and 2 per cent vitamin diets. Gro wth of caecal lactobacilli was stimulated more by calorie restriction, and growth of bifidobacteria was stimulated more by vitamin restricti on. The enhanced growth of fermentative bacteria in the caecal microbi ota of rats by vitamin and calorie restriction is discussed in relatio n to microbial competition or antagonism.