Effect of Food Restriction on Caecal Microbiota and Short-Chain Fatty Acid Concentrations in Rats

The effect of food restriction on the caecal bacterial and short-chain fatty acid (SCFA) concentrations in Wistar rats was studied since food restriction (FR) and the intestinal microbiota have effects on aging and other physiological processes of laboratory animals. Rats were fed a purified diet id libitum (control), and 80 per cent or 60 per cent of the control intake. FR resulted in increased numbers of bifidobacteria, Bacteroidaceae, and lactobacilli in proportion to the restriction rate. In particular. bifidobacteria significantly increased in the 60 per cent fed group (P<0.05); and Bacteroidaceae in the 60 per cent fed group (P<O.OOI) and in the 80 per cent fed group (P<0.001). Enterococci and staphylococci did not change in concentration during F R. The number of cnterobacteria decreased somewhat, but not significantly, in the 40 per cent FR. The total SCFA concentrations were reduced remarkably in proportion to the FR rate, especially butyrate which decreased strikingly compared with the other SCFAs. The present results suggest that FR may influence the physiological processes in age changes through alterations in the gut microbiota and its metabolic products. KEY WORDS: food restriction; rats; caecal microbiota: caecal short-chain fatty acid