Effect of Oligosaccharides and Fibre Substitutes on Short-chain Fatty Acid Production by Human Faecal Microflora

The microbial fermentation of dietary fibre and oligosaccharides has been shown to be involved in several physiological mechanisms that promote colonic health. One of these beneficial mechanisms is the production of short-chain fatty acid (SCFA) as the main by-products of dietary fibre and oligosaccharide microbial fermentation. Major SCFAs produced are acetate, propionate and butyrate. Each of these acids appear also to be involved in selective physiological events that lead to improving health. This study evaluated the fermentation of several oligosaccharides and commercial fibre substitutes using fresh faecal inocula. Typical SCFA production after 24 h was 42.4±5.5 mg/ml. Results indicated that hydrolyzed guar gum after 24 h significantly (P=0.0001) produced the highest levels of total SCFA (54.6±0.7 mg/ml) and was involved as well in high production of propionate and butyrate (19.8±0.3 and 15.5±0.03 mg/ml, respectively). Cellulose and psyllium husk were also involved in high production of propionate (21.0±0.5) and butyrate (16.8±0.5 mg/ml), respectively. The results of this study indicated several differences in the production of SCFAs by colonic microflora in the presence of oligosaccharides and fibre substitutes. The important physiological implications of these findings are discussed.