Background/Aims: Fruit, vegetables and cereals are rich in dietary fibre, vitamins, minerals and phytochemicals. Dietary fibres exhibit prebiotic effects by selectively promoting the growth of beneficial bacteria (Bifidobacterium spp., Lactobacillus spp.). This study determined the effect of short-term feeding of dietary fibres from cereals, fruit and vegetables on selective faecal bacteria and polysaccharide content using the rat as a model of the mammalian digestive tract.
Methods: Ten-week old rats were fed experimental diets containing 10% cellulose (control), barley β-glucan, broccoli fibre, citrus pectin, inulin, potato fibre, potato resistant starch, or wheat bran, for 7 days. On the final day, faeces were collected from each rat and stored at -80°C for microbiota and polysaccharide analysis.
Results: The numbers of Bifidobacterium spp. were greatest when the rats were fed inulin and potato fibre, while the Lactobacillus spp. numbers were enhanced when the rats were given the potato resistant starch and wheat bran diets. Total numbers of faecal bacteria were highest for the rats fed potato resistant starch and lowest for the rats fed citrus pectin. Levels of polysaccharide measured in the faeces was highest for the rats fed cellulose and lowest for the rats fed barley β-glucan, citrus pectin and inulin (P<0.001).
Conclusions: Faecal polysaccharide content reflects the fermentability of these different fibre sources. Consumption of different types of dietary fibre in rats showed differences in faecal microbiota composition, which is likely due to the different abilities/preferences of bacteria for different dietary substrates.
Funding source: MBIE