Influences of dietary oils and fats, and the accompanied minor content of components on the gut microbiota and gut inflammation: A review

The processing of dietary lipids in the intestinal lumen involves metabolic processes of the host and also of the microbial organisms that reside in the gut. Whereas, in the edible oil, there are also other minor content of components, such as fat-soluble micronutrients. The dietary oils and fats, as well as these accompanied components have different effects on the gut microbiota structure, which is also closely associated with gut inflammation, and the host health. This review of the literature highlights the effects of dietary oils and fats, as well as the minor content of accompanied components on the gut microbiota, and the gut inflammation, with special respect to illustrating the roles of high fat diet (HFD), fatty acid composition, the n6/n3 poly-unsaturated fatty acid (PUFA) ratio, the conjugated linoleic acids (CLAs), the fatty acid chain length and triacylglycerol (TAG) structure, the fat-soluble micronutrients, and some other minor content of components, such as trans-fatty acids (TFAs). The interactions between the dietary oils and fats and gut microbiota are also briefly discussed. The diversity in dietary oils and fats composition affects the gut microbiota structure, and the unhealthy dietary lipid pattern, such as HFD or diet rich in saturated fats may lead to the gut microbiota dysbiosis not only by decreasing their richness and diversity, but also by changing the Firmicutes to Bacteroidetes ratio, further raising the intestinal pro-inflammatory cytokines levels and permeability of the intestine mucosa. The balanced dietary oils and fats intake is recommended to achieve the appropriate fatty acid consumption ratio, especially for the n6/n3 PUFA ratio, thereafter, maintaining both of the gut microbiota homeostasis and host health. The accompanied minor content of fat-soluble bioactive components also showed positive roles for the overall gut health. However, more clinic evidence should be provided in future studies.