Effect of Vitamin Restriction on Caecal Bacteria and Short-Chain Fatty Acid Concentrations in Rats

Abstract

Food restriction and intestinal bacteria had been reported to have effects on the physiological processes of laboratory animals. Therefore, a study was carried out on the effect of vitamin restriction on the caecal bacteria and short-chain fatty acid (SCFA) concentrations in Wistar rats. In rats fed ad libitum with a purified diet with a 0.3 per cent vitamin mixture, concentrations of bifidobacteria increased significantly (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 this was not significant. Overgrowth of aerobic bacteria such as enterobacteria and enterococci was not found in the 0.3 per cent group. SCFA concentrations were reduced, but not significantly, in the 0.3 per cent 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, lactobacilli increased in the 50 per cent restricted group, but not significantly. Significantly decreased concentrations (P<0.01) of staphylococci 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. Growth of caecal lactobacilli was stimulated more by calorie restriction, and growth of bifidobacteria was stimulated more by vitamin restriction. The enhanced growth of fermentative bacteria in the caecal microbiota of rats by vitamin and calorie restriction is discussed in relation to microbial competition or antagonism. Keywords: Vitamin and calorie restriction, Caecal bacteria, Bifidobacteria, Lactobacilli, Short-chain fatty acids, Rat