Dietary index for gut microbiota and risk of metabolic syndrome: the mediating role of hepatic steatosis in a prospective cohort study
摘要
Metabolic syndrome (MetS) is a growing public health concern, with emerging evidence implicating that gut microbiota plays a role in MetS pathogenesis. The Dietary Index for Gut Microbiota (DI-GM) quantifies diet quality in relation to microbial diversity. This study examined the association between DI-GM and MetS risk, evaluating hepatic steatosis as a potential mediator.
MethodsThis prospective cohort included 4,503 adults (20–70 years) from the Monitoring of Metabolic Diseases Risk Factors in Tehran (MMRT) study, followed over five years. Dietary intake was assessed using a validated 125-item food frequency questionnaire to calculate DI-GM scores. Hepatic steatosis was quantified via controlled attenuation parameter (CAP) using transient elastography. MetS was defined according to Adult Treatment Panel III criteria. Multivariable logistic regression and mediation analyses evaluated associations.
ResultsHigher DI‑GM scores were associated with lower MetS incidence. In the fully adjusted model (Model 2), participants in the highest DI‑GM quartile had a 66% lower odds of MetS compared with the lowest quartile (OR = 0.34; 95% CI: 0.27–0.43; P‑trend < 0.001). Each one‑unit increase in the DI‑GM score was associated with an 18% decrease in the odds of MetS (OR = 0.82; 95% CI: 0.78–0.85; P < 0.001). All five MetS components showed significant inverse associations, with the strongest effects observed for elevated waist circumference, hypertriglyceridemia, and low high‑density lipoprotein cholesterol. In mediation analysis, hepatic steatosis accounted for approximately 65% of the DI‑GM–MetS association (indirect effect: −0.0263; P < 0.01), although causal interpretation is limited by the observational design.
ConclusionGreater adherence to a gut microbiota-supportive diet, as measured by DI-GM, is associated with a reduced risk of MetS, largely mediated by reductions in hepatic fat. These findings highlight the potential of microbiome-oriented dietary interventions for MetS prevention.
Graphical abstract