Genetically Predicted Milk Intake and Risk of Neurodegenerative Diseases

Nutrients. 2021 Aug 23;13(8):2893. doi: 10.3390/nu13082893.

Abstract

Milk intake has been associated with risk of neurodegenerative diseases in observational studies. Nevertheless, whether the association is causal remains unknown. We adopted Mendelian randomization design to evaluate the potential causal association between milk intake and common neurodegenerative diseases, including multiple sclerosis (MS), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). Genetic associations for neurodegenerative diseases were obtained from the International Multiple Sclerosis Genetics Consortium (n = 80,094), FinnGen consortium (n = 176,899), AD GWAS (n = 63,926), Web-Based Study of Parkinson's Disease (n = 308,518), PDGene (n = 108,990), and ALS GWAS (n = 80,610). Lactase persistence variant rs4988235 (LCT-13910 C > T) was used as the instrumental variable for milk intake. Genetically predicted higher milk intake was associated with a decreased risk of MS and AD and with an increased risk of PD. For each additional milk intake increasing allele, the odds ratios were 0.94 (95% confidence intervals [CI]: 0.91-0.97; p = 1.51 × 10-4) for MS, 0.97 (0.94-0.99; p = 0.019) for AD and 1.09 (95%CI: 1.06-1.12, p = 9.30 × 10-9) for PD. Genetically predicted milk intake was not associated with ALS (odds ratio: 0.97, 95%CI: 0.94-1.01, p = 0.135). Our results suggest that genetically predicted milk intake is associated with a decreased risk of MS and AD but with an increased risk of PD. Further investigations are needed to clarify the underlying mechanisms.

Keywords: causal effect; milk; neurodegenerative disease.

MeSH terms

  • Alzheimer Disease / epidemiology
  • Alzheimer Disease / genetics
  • Amyotrophic Lateral Sclerosis
  • Animals
  • Case-Control Studies
  • Databases, Genetic
  • Gene-Environment Interaction*
  • Genetic Association Studies
  • Genetic Predisposition to Disease
  • Humans
  • Lactase / genetics*
  • Mendelian Randomization Analysis
  • Milk* / adverse effects
  • Multiple Sclerosis / epidemiology
  • Multiple Sclerosis / genetics
  • Neurodegenerative Diseases / diagnosis
  • Neurodegenerative Diseases / epidemiology
  • Neurodegenerative Diseases / genetics*
  • Parkinson Disease / epidemiology
  • Parkinson Disease / genetics
  • Polymorphism, Single Nucleotide*
  • Risk Assessment
  • Risk Factors

Substances

  • Lactase