Dietary Lipids, Gut Microbiota, and Their Metabolites: Insights from Recent Studies

Dietary lipid intake can influence the gut microbiota (GM) and their metabolites, such as short-chain fatty acids (SCFA) and bile acids, which are key mediators of health. The objective is to examine how dietary lipids' quantity and quality influence the GM and metabolite profiles. A literature review of 33 studies in animals and humans was performed on the effects of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), trans-fatty acids (TFAs), and sterols on GM composition and gut-derived metabolites. The results show that diets rich in MUFAs, n-3 PUFAs, and short-chain FAs have the potential to enhance beneficial bacteria and metabolites. In addition, trans-palmitoleic acid, conjugated linoleic acid, and phytosterols may also have potentially beneficial effects on GM, but more research is needed. Medium-chain FAs and n-6 PUFAs have variable effects on the GM. Conversely, intakes of high-fat diets, long-chain SFAs, industrial TFAs, and cholesterol disrupt GM balance. In conclusion, animal studies clearly demonstrate that dietary fats influence the GM and related metabolites. Yet, human studies are limited. Therefore, well-designed human studies that consider the whole diet and baseline health status are needed to better understand the effects of dietary lipids on GM.