Erythrocyte n-6 polyunsaturated fatty acids, gut microbiota and incident type 2 diabetes: a prospective cohort study
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RESEARCH DESIGN AND METHODS We evaluated 2,731 participants without type 2 diabetes recruited between 2008-2013 in the Guangzhou Nutrition and Health Study, China. Type 2 diabetes cases were identified with clinical and biochemical information collected at follow-up visits. Using stool samples collected during the follow-up in the subset (n=1,591), 16S rRNA profiling was conducted. Using multivariable-adjusted Poisson or linear regression, we examined associations of erythrocyte n-6 PUFA biomarkers with incident type 2 diabetes, and diversity and composition of gut microbiota.
RESULTS Over 6.2 years of follow-up, 276 type 2 diabetes cases were identified (risk=0.10). Higher levels of erythrocyte γ-linolenic acid (GLA), but not linoleic or arachidonic acid, were associated with higher type 2 diabetes incidence. Comparing the top to the bottom quartile groups of GLA levels, relative risk was 1.72 (95% confidence intervals: 1.21, 2.44) adjusted for potential confounders. Baseline GLA was inversely associated with gut microbial richness and diversity (α-diversity, both p<0.05) during follow-up, and significantly associated with microbiota β-diversity (p=0.002). α-diversity acted as a potential mediator in the association between GLA and type 2 diabetes (p<0.05). Seven genera (Butyrivibrio, Blautia, Oscillospira, Odoribacter, S24-7 other, Rikenellaceae other, and Clostridiales other) were enriched in quartile 1 of GLA, and in participants without type 2 diabetes.
CONCLUSIONS Relative concentrations of erythrocyte GLA were positively associated with incident type 2 diabetes in a Chinese population and also with gut microbial profiles. These results highlight that gut microbiota may play an important role linking n-6 PUFA metabolism and type 2 diabetes etiology.