In October 2019 researchers from Germany published their review of the medical scientific literature to assess the impact of vegan or vegetarian diet on the make-up of the gut microbiome. In addition, a study involving vegan individuals was undertaken. A total of 16 studies were included in the review, 6 involving vegetarians and vegans, 6 vegans only and 4 compared the gut microbiome found in vegetarians and omnivores. Results showed that there were 5 different phyla, 28 families, 96 genera and 177 species, with Bacteroides, Bifidobacterium and Prevotella being the most reported genera followed by Prevotella copri, Faecalibacterium prausnitzii and Escherichia coli, irrespective of diet. No consistent association between a vegan diet or vegetarian diet and make-up of the gut microbiome compared to omnivores could be identified. In fact some studies produced contradictory results. The researchers felt that this could be due to the high variability in the gut microbiome and/or differences in the applied approaches. Further research is required to clarify this issue.
Trefflich I et al. Is a vegan or a vegetarian diet associated with the microbiota composition in the gut? Results of a new cross-sectional study and systematic review. Crit Rev Food Sci Nutr. 2019 Oct 21:1-15.