Short-chain fatty acids as a link between diet and cardiometabolic risk: a narrative review

Abstract

Aim: Diet has a profound impact on cardiometabolic health outcomes such as obesity, blood glucose, blood lipids and blood pressure. In recent years, the gut microbiota has emerged as one of several potential key players explaining dietary effects on these outcomes. In this review we aim to summarise current knowledge of interaction between diet and gut microbiota focusing on the gut-derived microbial metabolites short-chain fatty acids and their role in modulating cardiometabolic risk.

Findings: Many observational and interventional studies in humans have found that diets rich in fibre or supplemented with prebiotic fibres have a favourable effect on the gut microbiota composition, with increased diversity accompanied by enhancement in short-chain fatty acids and bacteria producing them. High-fat diets, particularly diets high in saturated fatty acids, have shown the opposite effect. Several recent studies indicate that the gut microbiota modulates metabolic responses to diet in, e.g., postprandial blood glucose and blood lipid levels. However, the metabolic responses to dietary interventions, seem to vary depending on individual traits such as age, sex, ethnicity, and existing gut microbiota, as well as genetics. Studies mainly in animal models and cell lines have shown possible pathways through which short-chain fatty acids may mediate these dietary effects on metabolic regulation. Human intervention studies appear to support the favourable effect of short-chain fatty acid in animal studies, but the effects may be modest and vary depending on which cofactors were taken into consideration.

Conclusion: This is an expanding and active field of research that in the near future is likely to broaden our understanding of the role of the gut microbiota and short-chain fatty acids in modulating metabolic responses to diet. Nevertheless, the findings so far seem to support current dietary guidelines encouraging the intake of fibre rich plant-based foods and discouraging the intake of animal foods rich in saturated fatty acids.

Keywords: Diet; Gut microbiota; Human studies; Metabolic effects; Short-chain fatty acids.

Fig. 1

Overview of microbiota

Fig. 2

Simplified rank-based classification of the butyrate producer Faecalibacterium prausnitzii

Fig. 3

The major bacterial phyla in the gut

Fig. 4

Effect of dietary fibre on glycaemic control and appetite, and possible pathways. A Dietary fibres escape digestion in the small intestine and B) are fermented into SCFA acids by gut bacteria in the colon. C) The SCFA bind to G-protein coupled receptors in enteroendocrine L-cells. D This causes increased secretion of GLP-1, GLP-2, leptin and PYY in response to a meal. E) GLP-1 improves regulation of blood glucose by enhancing release of insulin and suppressing release of glucagon from pancreas. GLP-1 also protects the beta-cells. GLP-1, leptin, and PYY enhance satiety by affecting the brain and the gastrointestinal system. GLP-2 maintains the intestinal barrier and may, thus, prevent systemic inflammation. GLP-1 and 2, glucagon-like peptide 1 and 2; PYY, peptide YY; SCFA, short-chain fatty acids. Figure was produced using Servier Medical Art and reproduced from first author’s thesis