Omega-6 fatty acid biomarkers and incident type 2 diabetes: pooled analysis of individual-level data for 39 740 adults from 20 prospective cohort studies

BACKGROUND: Metabolic effects of omega-6 polyunsaturated fatty acids (n-6 PUFA) remain contentious, and evidence is limited regarding their potential role in primary prevention of type 2 diabetes (T2D). METHODS: Global consortium of 20 prospective cohort studies with new, harmonized, individual-level analyses. Each study measured biomarker linoleic acid (LA, the major dietary PUFA) and arachidonic acid (AA, a precursor of metabolic- and inflammation-mediating metabolites) at baseline among adults without prevalent T2D. Associations of n-6 PUFA biomarkers with T2D risk were assessed prospectively using a pre-specified analytic plan for exposures, covariates, and effect modifiers. Findings were pooled using inverse-variance weighted meta-analysis. FINDINGS: This study comprised 39,740 adults from 10 countries, with age (range of cohort means) 49-76yrs and BMI, 23∙3-28∙4kg/m2, including 4,347 incident T2D cases during 366,073 person-years of follow-up. In multivariable-adjusted pooled analyses, higher LA biomarker associated with 35% lower risk of T2D (RR per interquintile range: 0∙65, 95%CI: 0∙60-0∙72, P