Abstract P219: Dairy Consumption and Body Mass Index: Mendelian Randomization Analysis of 184,802 Participants and Systematic Review of 37 Randomized Controlled Trials

Abstract

Objective: Using the Mendelian randomization (MR) approach and meta-analysis of selected randomized controlled trials (RCTs), we aimed to assess whether dairy intake was causally related to BMI. Methods: We used a genetic polymorphism in MCM6 ( LCT -13910 C/T, rs4988235), located upstream of the lactase gene ( LCT), as an instrumental variable (IV) for dairy intake in a MR design. The causal effect of dairy intake on BMI was quantified by IV estimators among 184,802 participants from 25 studies. We further conducted a new meta-analysis of RCTs on the effect of dairy consumption on changes in body composition among 3,007 participants in 37 RCTs. Results: Higher dairy intake was associated with higher BMI (multivariable-adjusted β = 0.03 kg/m 2 per serving/day; 95% CI, 0.00, 0.06; p=0.04), while the LCT -13910 C/T CT+TT genotype was significantly associated with higher dairy intake (β = 0.20 serving/day; 95% CI, 0.14, 0.25; p=3.15х10 -12 ) and higher BMI (β = 0.12 kg/m 2 ; 95% CI, 0.06, 0.17; p=2.11х10 -5 ). The IV analysis showed that higher dairy intake was significantly associated with higher BMI (β = 0.60 kg/m 2 per serving/day; 95% CI, 0.27, 0.92; p=3.0х10 -4 ). In addition, our systematic review of 37 RCTs indicated that higher dairy intervention significantly increased body weight (0.36 kg, 95% CI: 0.01, 0.70) and marginally increased lean mass (0.14 kg, 95% CI: -0.06, 0.33) in trials without energy restriction. Conclusions: The present study provides evidence to support a causal effect of higher dairy intake in the absence of caloric restriction on increased BMI.