Dietary fibres and Resistant Starches

Dietary fibre can be either soluble or insoluble fibre. Dietary fibre is defined as food material, particularly plant material, that is not hydrolysed by enzymes secreted by the human digestive tract, but that may be digested my microflora in the gut. Dietary fibre from plant material includes non-starch polysaccharides eg celluloses, some hemi-celluloses, gums and pectins as well as resistant starches.dietary fibre

Foods high in fibre, because of their consistency, encourage mastication and stimulate the secretion of digestive juices. In the colon, dietary fibre tends to increase faecal bulking due to increased water retention, and the insoluble dietary fibre reduces transit time. Transit time is particularly important because the conversion of sterol to carcinogenic polycyclic aromatic hydrocarbons is known to happen over time.

Resistant starches make up approximately 10 percent of the dietary intake of starch. Resistant starches are the starch that is not digested in the small intestine and that passes into the large intestine where it is a substrate for bacterial fermentation. dietary fibre
The bacteria produce short chain fatty acids from the resistant starches that may help maintain the health of the cells lining the colon and prevent bowel cancer. These fatty acids are also absorbed into the bloodstream and may play a role in lowering blood cholesterol levels.

Foods that contain resistant starches are whole grain cereals, nuts and seeds, legumes and unripe fruit especially bananas.