Key Findings
In this systematic review and meta-analysis of prospective studies, estimated dietary consumption and circulating biomarkers of ALA were correlated with a small none statistically significant reduction on the risk of diabetes mellitus (DM). In some of the studies reviewed, dietary ALA or flaxseed oil enhanced insulin sensitivity and glycemic responses. Fasting plasma glucose and markers of insulin resistance were moderately improved in short term randomized clinical trials. Neither EPA plus DHA, or fish and seafood intake showed any associations with risk reduction of DM overall.
ABSTRACT
The relationship between omega 3 polyunsaturated fatty acids from seafood (eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) or plant (alpha linolenic acid, ALA) sources and risk of type 2 diabetes mellitus (DM) remains unclear. We systematically searched multiple literature databases through June 2011 to identify prospective studies examining relations of dietary n3 PUFA, dietary fish and per or seafood, and circulating n3 PUFA biomarkers with incidence of DM. Data were independently extracted in duplicate by 2 investigators, including multivariate adjusted relative risk (RR) estimates and corresponding 95 per cent CIs. Generalized least squares trend estimation was used to assess dose response relationships, with pooled summary estimates calculated by both fixed effect and random effect models. From 288 identified abstracts, 16 studies met inclusion criteria, including 18 separate cohorts comprising 540,184 individuals and 25,670 cases of incident DM. Consumption of fish and or seafood was not significantly associated with DM nor were consumption of EPA plus DHA or circulating levels of EPA plus DHA biomarkers . Both dietary ALA and circulating ALA biomarker levels were associated with non significant trend towards lower risk of DM. Substantial heterogeneity (I2 to 80 per cent) was observed among studies of fish and seafood or EPA plus DHA and DM; moderate heterogeneity (greater than 55 per cent ) was seen for dietary and biomarker ALA and DM. In unadjusted meta regressions, study location (Asia vs. North America and Europe), mean BMI, and duration of follow up each modified the association between fish seafood and EPA plus DHA consumption and DM risk . We had limited statistical power to determine the independent effect of these sources of heterogeneity due to their high colinearity. The overall pooled findings do not support either major harms or benefits of fish or seafood or EPA plus DHA on development of DM, and suggest that ALA may be associated with modestly lower risk. Reasons for potential heterogeneity of effects, which could include true biologic heterogeneity, publication bias, or chance, deserve further investigation. (Authors abstract)
This is a free article, click below to view:
Link to Full Text