Fermentation of dietary starch in man.

Ahmed, Rashid
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Dietary starch that escapes digestion in the small intestine may be quantitatively more important than dietary fibre as substrate for fermentation. The products of fermentation have important implications in the pathogenesis of colorectal cancer and other diseases of the large bowel which are uncommon in Africans, but have a high prevalence in Western populations. Maize porridge is a staple of most Blacks in South Africa. Stale maize porridge (high resistant starch - HRS) seems to induce greater fermentation in the large bowel than fresh maize porridge (low resistant starch - LRS). In the present study, healthy colostomy subjects fed stale maize porridge had significantly more production of SCFA (short chain fatty acids) (mean SCFA - HRS = 182,6; mean SCFA - LRS = 116,1; p<0,05) in their colostomy effluent together with a significant drop in stool pH (mean pH - HRS = 5,91; mean pH - LRS = 6,70; p<0.G01). The SCFA butyrate tmean - HRS = 35,1; mean - LRS - LRS = 17,6; p<0,05) and acetate (mean - HRS = 93,9; mean - LRS = 65,8; p <0,05) were significantly elevated on the stale maize porridge diet when compared with consumption of fresh maize porridge. SCFA, propionate (mean - HRS = 43,1; mean - LRS = 24,8; p=G,Q5), also increased with stale maize porridge, but was not statistically significant. A high resistant starch diet and its resultant increase in fermentation products may be partly responsible in protecting the Black population against colorectal cancers and other large bowel diseases.