Abstract:
Carbohydrates are an important part of a nutritional diet. The healthiest sources include complex
carbohydrates because of their blunted effects on blood glucose. Whole grain consumption is
associated with diminished risk of serious, diet-related diseases, which are major problems in
wealthy industrialized economies and are emerging in developing countries demographic and
nutrition transition. Carbohydrates are important contributors to the health benefits of whole
grains. Insoluble non-starch polysaccharides (NSP) are effective laxatives. Soluble NSP lower
plasma cholesterol and so can reduce heart disease risk but the effect is inconsistent. Processing
seems to be an important contributor to this variability and other grain components may be
involved. However, starch not digested in the small intestine (resistant starch, RS) appears to be
as important as NSP to large bowel function. Native Africans at low risk of diet-related disease
through consumption of unrefined cereals may actually have relatively low fibre intakes. While
NSP are effective faecal bulking agents, they are fermented to a very variable extent by the large
bowel microflora. In contrast, RS seems to act largely through the short chain fatty acids (SCFA)
produced by these bacteria. One SCFA (butyrate) appears to be particularly effective in
promoting large bowel function and RS fermentation appears to favour butyrate production.
Animal studies show that dietary RS lowers diet-induced colonocyte genetic damage and
chemically-induced large bowel cancer which correlates with increased butyrate. These effects in
long term could contribute to a lower risk of cancer and ulcerative colitis. Cereal grain
oligosaccharide (OS) may also function as prebiotics and increase the levels of beneficial
bacteria in the large bowel |
