Alcohol consumption and its interaction with adiposity-associated genetic variants in relation to subsequent changes in waist circumference and body weight.

Background: Studies have suggested a link between alcohol intake and adiposity. However, results from longitudinal studies have been inconsistent, and a possible interaction with genetic predisposition to adiposity measures has often not been taken into account.
Objective: To examine the association between alcohol intake recorded at baseline and subsequent annual changes in body weight (∆BW), waist circumference (ΔWC) and WC adjusted for BMI (ΔWC _BMI ), and to test for interaction with genetic predisposition scores based on single nucleotide polymorphisms (SNPs) associated with various forms of adiposity.
Method: This study included a total of 7028 adult men and women from MONICA, the Diet, Cancer and Health cohort (DCH), and the Inter99 studies. We combined 50 adiposity-associated SNPs into four scores indicating genetic predisposition to BMI, WC, WHR _BMI and all three traits combined. Linear regression was used to examine the association of alcohol intake (drinks of 12 g (g) alcohol/day) with ΔBW, ΔWC, and ΔWC _BMI, and to examine possible interactions with SNP-scores. Results from the analyses of the individual cohorts were combined in meta-analyses.
Results: Each additional drink/day was associated with a ΔBW/year of -18.0 g (95% confidence interval (CI): -33.4, -2.6, P = 0.02) and a ΔWC of -0.3 mm/year (-0.5, -0.0, P = 0.03). In analyses of women only, alcohol intake was associated with a higher ΔWC _BMI of 0.5 mm/year (0.2, 0.9, P = 0.002) per drink/day. Overall, we found no statistically significant interactions between the four SNP-scores and alcohol intake in relation to changes in adiposity measures. However in analyses of women separately, we found interaction between the complete score of all 50 SNPs and alcohol intake in relation to ΔBW (P for interaction = 0.03). No significant interaction was observed among the men.
Conclusion: Alcohol intake was associated with a decrease in BW and WC among men and women, and an increase in WC _BMI among women only _. We found no strong indication that these associations depend on a genetic predisposition to adiposity.
Trial Registration: Registry: ClinicalTrials.gov Trial number: CT00289237 , Registered: 19 September 2005 retrospectively registered.