Mediterranean Diet Adherence Modulates Anthropometric Measures by TCF7L2 Genotypes among Puerto Rican Adults

BACKGROUND: Transcription factor 7-like 2 (TCF7L2) genetic variants that predispose individuals to type 2 diabetes (T2D) show inconsistent associations with anthropometric traits. Interaction between TCF7L2 genotypes and dietary factors may help explain these observations. OBJECTIVE: We aimed to examine the potential modulation of TCF7L2-rs7903146 and rs12255372 on anthropometric markers by a Mediterranean diet (MedDiet). METHODS: Cross-sectional analysis was conducted in 1120 participants (aged 45-75 y) of the Boston Puerto Rican Health Study. Anthropometric variables were measured, and polymorphisms were genotyped using standardized protocols. Diet was assessed using a validated FFQ. The MedDiet was defined based on adherence to 9 food and nutrient components using sex-specific population-based median cut-offs; high adherence was defined as meeting >/=4 components. Haplotypes were tested for association with obesity traits, independently and via interaction with the MedDiet. RESULTS: TCF7L2-rs7903146 showed significant interaction with the MedDiet influencing BMI, weight, and waist circumference. The T risk-allele carriers (CT + TT) with a high MedDiet score had lower weight (77.3 +/- 1.0 compared with CC 80.9 +/- 1.0 kg; P = 0.013) and waist circumference (99.2 +/- 0.9 compared with CC 102.2 +/- 0.9 cm; P = 0.021), when compared with CC participants. A low MedDiet score resulted in no significant differences between genotypes. For TCF7L2-rs12255372, we found significant interactions with the MedDiet for weight (P-interaction = 0.034) and BMI (P-interaction = 0.036). The T allele carriers with a higher MedDiet score showed a trend of lower but no significant differences when compared with CC participants for BMI (P = 0.19), weight (P = 0.09), and waist circumference (P = 0.11). We found significant interactions between the 2 risk-carrying haplotypes and the MedDiet compared with the common haplotype (GC), with lower BMI (beta +/- SE, TT: -1.53 +/- 0.68; P-interaction = 0.024), weight (TT: -4.16 +/- 1.77; P-interaction = 0.019), and waist circumference (GT: -5.07 +/- 2.50; P-interaction = 0.042) at a high MedDiet score. CONCLUSION: Puerto Ricans with the TCF7L2-rs7903146 and rs12255372 T2D risk genotypes, although still high, had better anthropometric profiles when adhering to a MedDiet, suggesting that this diet may offset unfavorable genetic predisposition.