Abstract 12833: Milk Intake is not Causally Associated with Risk of Ischemic Heart Disease or Myocardial Infarction - A Mendelian Randomization Study in 93,197 Danish Individuals
Introduction: Intake of milk is associated with reduced risk of ischemic heart disease(IHD) and myocardial infarction(MI) in meta-analyses of observational studies, but whether this association is causal is presently unknown.
Hypothesis: We investigated the hypothesis that milk intake is causally associated with reduced risk of IHD and MI.
Methods: We included 93,197 individuals from 3 Danish population studies (the Copenhagen City Heart Study(N=8,320), the Danish General Suburban Population Study(N= 11,439), and the Copenhagen General Population Study(N= 73,438)). Information on milk intake was self-reported. Information on IHD and MI were obtained from the national Danish Patient Registry and the national Causes of Death Registry in the period from 1977 to 2011; total numbers of IHD and MI were 8,851 and 3,639, respectively. We used the genetic variant C/T-13910 associated with lactose intolerance as a measure of lifelong milk-exposure in a Mendelian randomization design using instrumental variable analyses to obtain causal risk estimates of the effect of milk intake on risk of IHD and MI.
Results: No significant associations were found between milk intake and IHD/MI using prevalence or incidence data. Intake of milk was lowest among people with the lactose intolerant genotype CC compared to the lactose tolerant genotypes TC and TT (mean glasses/week (CI 95 %): CC=4.7(4.51-4.92), TC=6.5(6.36-6.57), TT=6.7(6.64-6.80); P=0.0001). Analysis using combined data from the three population studies showed no significant associations between genotypes and risk of IHD/MI. Observational hazard ratios for a 1 glass/week increase in milk intake was 1.00(0.99- 1.01) for both IHD and MI. The corresponding causal risk ratios for a 1 glass/week increase in milk intake was 1.00(0.96-1.06) and 0.98(0.92-1.06) for IHD and MI, respectively.
Conclusions: We find no evidence of a causal effect of milk intake on risk of ischemic heart disease or myocardial infarction.
- © 2013 by American Heart Association, Inc.