H H Vorster

Bio: H H Vorster is an academic researcher. The author has contributed to research in topics: Carbohydrate metabolism & Triglyceride. The author has an hindex of 1, co-authored 1 publications receiving 265 citations.

Colonic health: fermentation and short chain fatty acids.

Abstract: Interest has been recently rekindled in short chain fatty acids (SCFAs) with the emergence of prebiotics and probiotics aimed at improving colonic and systemic health Dietary carbohydrates, specifically resistant starches and dietary fiber, are substrates for fermentation that produce SCFAs, primarily acetate, propionate, and butyrate, as end products The rate and amount of SCFA production depends on the species and amounts of microflora present in the colon, the substrate source and gut transit time SCFAs are readily absorbed Butyrate is the major energy source for colonocytes Propionate is largely taken up by the liver Acetate enters the peripheral circulation to be metabolized by peripheral tissues Specific SCFA may reduce the risk of developing gastrointestinal disorders, cancer, and cardiovascular disease Acetate is the principal SCFA in the colon, and after absorption it has been shown to increase cholesterol synthesis However, propionate, a gluconeogenerator, has been shown to inhibit cholesterol synthesis Therefore, substrates that can decrease the acetate: propionate ratio may reduce serum lipids and possibly cardiovascular disease risk Butyrate has been studied for its role in nourishing the colonic mucosa and in the prevention of cancer of the colon, by promoting cell differentiation, cell-cycle arrest and apoptosis of transformed colonocytes; inhibiting the enzyme histone deacetylase and decreasing the transformation of primary to secondary bile acids as a result of colonic acidification Therefore, a greater increase in SCFA production and potentially a greater delivery of SCFA, specifically butyrate, to the distal colon may result in a protective effect Butyrate irrigation (enema) has also been suggested in the treatment of colitis More human studies are now needed, especially, given the diverse nature of carbohydrate substrates and the SCFA patterns resulting from their fermentation Short-term and long-term human studies are particularly required on SCFAs in relation to markers of cancer risk These studies will be key to the success of dietary recommendations to maximize colonic disease prevention

Functional food science and gastrointestinal physiology and function

Abstract: The gut is an obvious target for the development of functional foods, acting as it does as the interface between diet and the metabolic events which sustain life. The key processes in digestive physiology which can be regulated by modifying diet are satiety, the rate and extent of macronutrient breakdown and absorption from the small bowel, sterol metabolism, the colonic microflora, fermentation, mucosal function and bowel habit, and the gut immune system. The intestinal microflora is the main focus of many current functional foods. Probiotics are foods which contain live bacteria which are beneficial to health whilst prebiotics, such as certain non-digestible oligosaccharides which selectively stimulate the growth of bifidobacteria in the colon, are already on the market. Their claimed benefits are to alleviate lactose maldigestion, increase resistance to invasion by pathogenic species of bacteria in the gut, stimulate the immune system and possibly protect against cancer. There are very few reports of well-designed human intervention studies with prebiotics as yet. Certain probiotic species have been shown to shorten the duration of rotavirus diarrhoea in children but much more work is needed on the mechanism of immunomodulation and of competitive exclusion and microflora modification. The development of functional foods for the gut is in its infancy and will be successful only if more fundamental research is done on digestive physiology, the gut microflora, immune system and mucosal function.