Huang T, Afzal S, Yu C, et al. - Via Mendelian randomization (MR) design used in the China Kadoorie Biobank, the Copenhagen City Heart Study, and the Copenhagen General Population Study, researchers investigated the causal relationship of 25-hydroxyvitamin D (25[OH]D) with myocardial infarction, stroke, ischaemic heart disease, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and lipid levels among both Chinese and Europeans. In Chinese adults, plasma 25(OH)D levels were not significantly related to cause-specific vascular disease or mortality, with the exception of intracerebral hemorrhage. Plasma 25(OH)D levels were inversely correlated with all types of vascular diseases and mortality in Europeans. Nonetheless, in both Chinese and European adults, MR analysis did not illustrate causal relations of genetically raised 25(OH)D levels with cause-specific vascular diseases or mortality. Moreover, each 25 nmol/L higher 25(OH)D was observationally correlated with lower total cholesterol and low-density lipoprotein cholesterol levels, but greater high-density lipoprotein cholesterol levels. Similarly, MR analysis explicated that 25(OH)D levels were not causally connected to lipids in both Chinese and European adults following Bonferroni correction. In conclusion, no evidence to support that genetically raised 25(OH)D was related to a lower risk of ischaemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, and lipid levels in both Chinese and European adults, were discovered. Moreover, the inverse relations of vitamin D with vascular disease could be the outcome of confounding.