The vegan diet, a health risk?
A comparative study of vegans and omnivores concludes that diet influences the salivary microbiota, which could be the source of various inflammatory diseases.
While the impact of diet on the intestinal microbiota has been the subject of many investigations, its impact on the salivary microbiota has been relatively little studied. Yet several epidemiological studies have established a link between periodontal disease (destruction of the gums and the bones supporting the teeth), and various cardiovascular and metabolic diseases (obesity, insulin resistance, type 2 diabetes). Their common factor? Chronic inflammation triggered by periodontal disease, which leads to the excess production of toxins. A hypothesis confirmed by studies in mice, which suggest a direct role for the salivary microbiota, probably modulated by diet, in the development of metabolic and cardiovascular diseases.
More species associated with periodontal disease in vegans
Following these observations, a Danish team compared the salivary microbiota of omnivores and vegans. They detected differences, both in its structure and composition. The discrepancies focused on around thirty bacterial groups; among these, two species associated with periodontal disease were overrepresented in vegans. More extensive analyses demonstrated differences in relation to the diversity of the metabolic pathways used by the bacteria, probably because of an adaptation of the microbiota to diet, the content of which varies considerably between vegans and omnivores in terms of proteins, dairy products and fibers.
A link between the oral microbiota and systemic diseases
The authors noted that the association between the presence of certain bacteria and markers of inflammation supports the hypothesis that there is a link between the oral microbiota and systemic diseases (inflammatory diseases affecting several organs simultaneously). Finally, they considered that dietary habits and certain nutrients contribute in a general way to the fashioning of the salivary microbiota. In this respect, eating a vegan diet influences the oral flora as does any dietary behavior over the long term. This is a first step towards future analyses, which will aim to shed light on the specific features and possible risks of the vegan diet.
Hansen et al. Impact of a vegan diet on the human salivary microbiota. Nature Scientific Reports (2018) 8:5847, DOI:10.1038/s41598-018-24207-3