Maybe this explains it, still, mysteries abound!
Colonic Digestive Health - Resistant Starch
The fermentation of resistant starch increases short-chain fatty acids in the colon. The fermentation of resistant starch produces more butyrate than other fibers tested.4 Butyrate is particularly important because it is the primary energy source for colonic cells and has anti-inflammatory properties that are important for keeping colon cells healthy.5, 6
In addition, butyrate has anti-carcinogenic properties. Published research has shown that butyrate inhibits the growth and proliferation of tumor cell lines in vitro7, it induces differentiation of tumor cells, producing a phenotype similar to that of the normal mature cell, 8 and it induces apoptosis or programmed cell death of human colorectal cancer cells.
· The fermentation of resistant starch reduces intestinal pH and the production of potentially harmful secondary bile acids, ammonia and phenols.9
· Resistant starch prevents the degradation of the mucous layer within the colon. This mucous layer is believed to protect colon cells.10
· Resistant starch may help to reduce the risk of colorectal cancer. Three mechanisms are believed to be involved in the protection against the development and growth of cancer cells – initiation, differentiation and apoptosis. Resistant starch has been shown to protect colon cells from DNA damage11; to promote the normalization (i.e. differentiation) of cancerous cells within the colon and increase the apoptosis (programmed cell death) of cells damaged by carcinogens.12 A recent clinical study found that resistant starch reduced the proportion of mitotic cells in the top half of colonic crypts (a marker for pre-malignancy), and increased expression of cell cycle regulatory genes in patients with colorectal cancer. 13 A recent published multi-center clinical trial concluded that resistant starch was not effective in preventing colon cancer in individuals genetically predisposed to colon cancer (individuals wih Lynch Syndrome).14