Flavonoid subclasses and type 2 diabetes mellitus risk: a meta-analysis of prospective cohort studies

Abstract

Epidemiological studies have suggested controversial associations between flavonoid subclasses and type 2 diabetes mellitus (T2DM) risk. The aim of the present meta-analysis was to quantitatively estimate these associations with prospective cohort study. A systematic literature search in PubMed and Scopus databases was performed up to May 2018. Multivariate-adjust relative risks (RRs) with corresponding 95% confidence intervals (CIs) for the highest versus the lowest category were pooled by using a random-effects model. Using restricted cubic spline regression model, non-linear dose-response analysis was estimated. Nine independent prospective cohort studies with 172,058 participants and 16910 events were included. Dietary intakes of flavanols, flavonols, flavan-3-ols and isoflavones were inversely associated with T2DM risk, and the summary RRs were 0.86 (95%CI: 0.77, 0.97), 0.91 (95%CI: 0.85, 0.98), 0.90 (95%: 0.82, 0.99) and 0.91 (95%CI: 0.84, 0.98), respectively. Dose-response analysis showed that 135 mg/day increment of flavanols (95%CI: 0.92, 0.96; P for trend <0.001), 50 mg/day increment of flavonols (95%CI: 0.88, 0.99, P for trend = 0.021), 68 mg/day increment of flavan-3-ols (95%CI: 0.92, 0.96, P for trend <0.001), or 1.8 mg/day increment of isoflavones (95%CI: 0.92, 0.97, P for trend <0.001) were associated with 6% reduction in T2DM risk. Non-significant association was observed with respect to flavanones and flavones. The present meta-analysis provides substantial evidence that dietary intakes of flavanols, flavonols, flavan-3-ols and isoflavones were inversely associated with T2DM risk, respectively. Higher dietary intakes of flavanol-, flavonol-, flavan-3-ol- and isoflavone-foods would have beneficial effects for protection against T2DM.

Keywords:

• Flavonoid subclasses
• type 2 diabetes mellitus
• prospective cohort study
• meta-analysis

Disclosure statement

None.

Additional information

Funding

This work is supported by the National Basic Research Program of China (973 Program: 2015CB553604); by National Natural Science Foundation of China (NSFC: 81773433); and by the Key scientific Research Projects in Shandong Provence China (2017YYSP007). The funders have no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.