The Impact of Alternative Protein Sources on Gut Microbiota: Limitations of the Current Understanding.

While the effects of carbohydrates and fibers on the gut microbiota are well established, the influence of proteins has only recently been explored. In addition, whereas the impacts of conventional protein sources remain partially defined, evidence is even more limited for alternative sources, such as insects, algae, and fungi. This commentary highlights the critical knowledge gaps in the context of the impact of alternative protein sources on gut microbiota, which need future investigation. This understanding becomes even more critical when considering that many of these sources are regarded as novel foods by large segments of the global population. Emerging findings suggest that differences in protein structure and digestibility may increase the protein content in the lumen, which in turn could enhance microbial protein fermentation and the production of poorly characterized metabolites. Moreover, the gut microbiota may be less adapted to metabolizing and managing such novel substrates if they were not previously part of the habitual diet. Therefore, well-designed clinical trials are urgently needed to understand the real potential effects of the alternative proteins on gut microbiota.