The effect of a combination of short-chain fatty acids on the lipid profiles of westernised black men

Abstract

South Africa is in the process of Westernisation, especially in the Black male population, with an adaptation of a westernised diet. Morbidity and mortality rates have increased because of the higher incidence of cerebrovascular and coronary heart disease (CHD) in this population group. Dietary fibre is used as one of the pillars in the prevention and treatment of CHD. Previous studies have shown that the addition of dietary fibre to the diet can significantly improve metabolic profiles, induding lipid profiles, of human subjects. A decrease, especially in the serum total cholesterol levels, is beneficial and is associated with a decreased risk of the development of CHD and atherosclerosis. It is believed that some of these beneficial effects may be mediated in part by the SCFAs produced during the microbial fermentation of dietary fibre in the large intestine. These SCFAs include acetate, propionate and butyrate. The main objective of this study was to examine the hypothesis that exposure to two different combinations of short-chain fatty acids (SCFAs), orally administered to a group of local westernised Black men will have beneficial effects on their lipid profiles. The concentration of SCFAs used was equivalent to that generated by the fermentation of 15g of mixed fibre. One of the supplements contained a mixture of acetate, propionate and butyrate in a ratio of 70% acetate, 15% propionate and 15% butyrate. The other supplement contained only a mixtore of acetate and propionate, in a ratio of 50% acetate and 50% propionate. It is believed that the increase of colonic acetate will have a positive effect on the lipid profile. The study was that of a randomised, placebo-controlled, double-blinded clinical trial. Voluntary members of the South African National Defence Force, Tempe Military Base, were recruited for this study, using a very strict set of indusion criteria. All subjects received a placebo for a period of one week following the collection of baseline blood samples. A second baseline blood sample was collected from each individual at the end of this period to ensure a stable baseline. Subjects were randomly assigned to three different intervention groups. Supplementation with the placebo, acetate-propionatebutyrate and acetate-propionate mixtures was sustained for a period of four weeks following the second baseline blood collection. Lipid profiles (including the serum-TC, -HDL-C, -LDL-C and non-esterified fatty acids (NEFA)), anthropometry, as well as some other general health markers were measured at each visit. Also, a 'wash-out' period of one week followed the supplementation phase. No significant changes in any of the lipid variables were observed in the placebo group. The acetate/propionatelbutyrate-supplement caused a nonsignificant decrease in the serum TC of apprOximately 8% after four weeks of supplementation. In contrast, the serum-LDL-C levels significantly decreased (-16%; from 3.10 mmol/L ± 0.78 to 2.61 ± 0.94 mmol/L) during the same period of time. In the study grollp receiving a combination of acetate and propionate salts, a beneficial statistically Significant increase of the serum HDL-C (from 1.21 ± 0.24 mmol/L to 1.35 ± 0.34 mmol/L) was observed, without any changes in the other lipid fractions. From the results it was evident that the inclusion of butyrate to the supplement was more beneficial in terms of lipid-lowering effects. These profile changes, associated with the additional intake of butyrate does reflect a decrease in risk for the future development of CHD. It can therefore be conduded that short-chain fatty acid supplements could be used to the benefit of those individuals suffering from lifestyle diseases: but that the most appropriate ratio of acetate, propionate and butyrate supplementation needs further research.