Abstract
AimsTo describe the abundance of major phyla and some genera in the gut microbiota of individuals according to dietary habits and examine their associations with inflammatory markers, insulin resistance, and cardiovascular risk profile.MethodsA total of 268 non-diabetic individuals were stratified into groups of dietary types (strict vegetarians, lacto-ovo-vegetarians, and omnivores). The taxonomic composition and phylogenetic structure of the microbiota were obtained through the analysis of the 16S rRNA gene. Samples were clustered into operational taxonomic units at 97% similarity using GreenGenes 13.5 database. Clinical, biochemical, and circulating inflammatory markers were compared by ANOVA or Kruskal–Wallis test.ResultsThe sample (54.2% women, mean age 49.5 years) was composed of 66 strict vegetarians, 102 lacto-ovo-vegetarians and 100 omnivores. Considering the entire sample, the greatest abundant phyla were Firmicutes (40.7 ± 15.9%) and Bacteroidetes (39.5 ± 19.9%), and no difference in abundances was found between individuals with normal and excess weight. Stratifying by dietary types, the proportion of Firmicutes was lower and of Bacteroidetes was higher in strict vegetarians when compared to lacto-ovo-vegetarians and omnivores. At the genus level, strict vegetarians had a higher Prevotella abundance and Prevotella/Bacteroides ratio than the other groups. They also had a lower proportion of Faecalibacterium than lacto-ovo-vegetarians, and both vegetarian groups had higher proportions than did omnivores. Succinivibrio and Halomonas from the Proteobacteria phylum were overrepresented in omnivores. The omnivorous group showed higher values of anthropometric data, insulin, HOMA-IR, and a worse lipid profile. Inflammatory markers exhibited a gradual and significant increase from the vegetarians and lacto-ovo-vegetarians to the omnivorous group.ConclusionsThere are differences in gut microbiota composition of individuals with distinct dietary habits, who differ according to their inflammatory and metabolic profiles. Based on the findings relative to bacteria abundances and on their recognized actions in the metabolism, we suggest that exposure to animal foods may favor an intestinal environment which could trigger systemic inflammation and insulin resistance-dependent metabolic disorders.
Highlights
The role of dietary habits for risk and for protection against cardiometabolic diseases is largely recognized [1]
Stratifying according to dietary type, 66 were strict vegetarians, 102 lacto-ovo-vegetarians, and 100 omnivores, and groups did not differ according to male-to-female ratios and age (49.6 ± 8.5, 49.6 ± 8.6, 49.1 ± 8.2 years, p = 0.878, respectively)
The frequencies of weight excess [26% versus 38% versus 55%, pre-diabetes [21% versus 29% and 36%], and hypertension [18% versus 26% and 33%] were higher in the omnivores than in lacto-ovo-vegetarians and strict vegetarians, respectively
Summary
The role of dietary habits for risk and for protection against cardiometabolic diseases is largely recognized [1]. While a high-fat low-fiber western diet has been associated with type 2 diabetes mellitus, dyslipidemia and cardiovascular disease, a vegetarian diet with a beneficial cardiometabolic profile and lower rates of cardiovascular events [2, 3]. It is known that the body fat accumulation is an underlying mechanism of cardiometabolic disease by triggering a low-grade inflammation and insulin resistance [5, 6]. There is a growing interest in the participation of gut bacteria mediating the dietinduced cardiometabolic risk [7,8,9]. Animal studies have contributed to understanding how bacterial communities influence energy extraction, fat deposition, inflammatory status and insulin sensitivity [10,11,12,13]
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