Fermentation of dietary starch in humans

Am J Gastroenterol. 2000 Apr;95(4):1017-20. doi: 10.1111/j.1572-0241.2000.01848.x.


Objective: Dietary starch that escapes digestion in the small intestine may be quantitatively more important than dietary fiber as a 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.

Methods: 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]).

Results: In the present study, healthy colostomy subjects fed stale maize porridge had significantly more production of short-chain fatty acids (SCFA) (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 < 0.001). The SCFA butyrate (mean, HRS = 35.1; mean, 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 = 0.05), also increased with stale maize porridge, but was not statistically significant.

Conclusion: A high-resistant starch diet and its resultant increase in fermentation products may be partly responsible for protecting the black population against colorectal cancers and other large bowel diseases.

MeSH terms

  • Acetic Acid / metabolism
  • Adult
  • African Continental Ancestry Group*
  • Butyrates / metabolism
  • Colorectal Neoplasms / prevention & control
  • Colostomy
  • Dietary Carbohydrates / metabolism*
  • Fatty Acids, Volatile / metabolism
  • Fermentation*
  • Gastrointestinal Transit / physiology
  • Humans
  • Hydrogen-Ion Concentration
  • Intestinal Mucosa / metabolism
  • Male
  • Risk Factors
  • South Africa
  • Zea mays / metabolism*


  • Butyrates
  • Dietary Carbohydrates
  • Fatty Acids, Volatile
  • Acetic Acid