Interactions of Dietary Whole-Grain Intake With Fasting Glucose- and Insulin-Related Genetic Loci in Individuals of European Descent A meta-analysis of 14 cohort studies

OBJECTIVE - Whole-grain foods are touted for multiple health benefits including enhancing insulin sensitivity and reducing type 2 diabetes risk Recent genome-wide association studies (GWAS) have identified several single nucleotide polymorphisms (SNPs) associated with fasting glucose and insulin concentrations in individuals free of diabetes We tested the hypothesis that whole-grain food intake and genetic variation interact to influence concentrations of fasting glucose and insulin RESEARCH DESIGN AND METHODS - Via meta-analysis of data from 14 cohorts comprising similar to 48 000 participants of European descent we studied interactions of whole-grain intake with loci previously associated in GWAS with fasting glucose (16 loci) and/or insulin (2 loci) concentrations For tests of interaction we considered a P value <0 0028 (0 05 of 18 tests) as statistically significant RESULTS - Greater whole grain food intake was associated with lower fasting glucose and insulin concentrations independent of demographics other dietary and lifestyle factors, and BMI (beta [95% Cl] per 1-serving greater whole grain intake -0 009 mmol/l glucose [-0 013 to -0 0051 P < 0 0001 and -0011 pmol/l [In] insulin [-0 015 to -0 0071 P = 0 0003) No interactions met our multiple testing adjusted statistical significance threshold The strongest SNP interaction with whole-grain intake was rs780094 (GCKR) for fasting insulin (P = 0 006) where greater whole-grain intake was associated with a smaller reduction in fasting insulin concentrations in those with the insulin raising allele