title: Genetically predicted milk consumption and bone health, ischemic heart disease and type 2 diabetes: a Mendelian randomization study.
abstract: Milk provides protein and micronutrients, and is recommended by some dietary guidelines, particularly for bone health. Meta-analysis of small randomized controlled trials suggests that milk may increase bone mineral density, but they are very heterogeneous. No randomized controlled trial has assessed the effects of milk on major chronic diseases. Previous Mendelian randomization studies of milk did not consider bone health, found no effects on ischemic heart disease (IHD) or type 2 diabetes (T2D) but higher body mass index. Using larger genetic studies, we estimated the effects of milk on osteoporosis, IHD, T2D, adiposity, lipids and glycemic traits.
  
  
  
  Instrumental variable analysis based on a genetic variant endowing lactase persistence (rs4988235 (MCM6)) was used to obtain estimates for osteoporosis (GEFOS), IHD (CARDIoGRAMplusC4D), T2D (DIAGRAM), adiposity (GIANT), lipids (GLGC) and glycaemic traits (MAGIC). Eye color was a negative control for IHD, as it mirrors the distribution of lactase persistence and IHD in Western Europe.
  
  
  
  Genetically predicted adult milk consumption was not clearly associated with bone mineral density, IHD (odds ratio (OR): 1.03 per s.d., 95% confidence interval (CI): 0.95-1.12) and or T2D (OR: 0.92, 95% CI: 0.83-1.02) but was associated with higher log-transformed fasting insulin (0.05, 95% CI: 0.02-0.07) and body mass index (0.06, 95% CI: 0.03-0.09). Genetically predicted eye color was not associated with IHD.
  
  
  
  The lack of association of genetically predicted milk consumption with bone health, IHD or T2D suggests few beneficial effects but is more consistent with milk promoting adiposity.
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Q
authors.identifier: 0000-0001-8778-4132
authors.initials: Q
authors.lastname: Yang
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: S L
authors.initials: SL
authors.lastname: Lin
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: S L
authors.initials: SL
authors.lastname: Au Yeung
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: M K
authors.initials: MK
authors.lastname: Kwok
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: G M
authors.initials: GM
authors.lastname: Leung
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.|School of Public Health and Health Policy, City University of New York, New York, NY, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Schooling
mesh_terms: D050154:Adiposity; D000328:Adult; D000818:Animals; D015992:Body Mass Index; D015519:Bone Density; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000517:prevention & control; D005060:Europe; D005260:Female; D005518:Food Preferences; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D057182:Mendelian Randomization Analysis; D008892:Milk / Q000009:adverse effects*; D064151:Minichromosome Maintenance Complex Component 6 / Q000235:genetics*; D017202:Myocardial Ischemia / Q000235:genetics* / Q000517:prevention & control; D010024:Osteoporosis / Q000235:genetics* / Q000517:prevention & control; D050177:Overweight / Q000209:etiology / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide
chemical_list: C103258:MCM6 protein, human; D064151:Minichromosome Maintenance Complex Component 6