Phenome-wide association study of genetically predicted B vitamins and homocysteine biomarkers with multiple health and disease outcomes: analysis of the UK Biobank

Although a number of health outcomes such as CVDs, metabolic-related outcomes, neurological disorders, pregnancy outcomes, and cancers have been identified in relation to B vitamins, evidence is of uneven quality and volume, and there is uncertainty about putative causal relationships. To explore the effects of B vitamins and homocysteine on a wide range of health outcomes based on a large biorepository linking biological samples and electronic medical records. First, we performed a phenome-wide association study (PheWAS) to investigate the associations of genetically predicted plasma concentrations (genetic component of the circulating concentrations) of folate, vitamin B6, vitamin B12, and their metabolite homocysteine with a wide range of disease outcomes (including both prevalent and incident events) among 385,917 individuals in the UK Biobank. Second, 2-sample Mendelian randomization (MR) analysis was used to replicate any observed associations and detect causality. We considered MR P