By Sally Robertson, BSc
A new genetic study has provided the most solid evidence to date that a low vitamin D level plays a causal role in the development of high blood pressure (hypertension).
Although research has previously pointed to a link between low vitamin D and hypertension, a discrepancy exists between the results of observational studies, which show a strong association, and those of clinical trials, which show no significant effect.
The current findings come from a Mendelian randomisation study that included data for over 146,500 patients of European ancestry from Europe and North America.
“Mendelian randomisation helps to determine cause and effect because by using genetic data we can better avoid confounding, reverse causation, and bias,” explains lead author of the study Professor Elina Hyppönen from the University of South Australia.
Hyppönen and colleagues used two common genetic variants known to affect levels of 25-hydroxyvitamin D [25(OH)D], a clinical marker of vitamin D status, to measure the relationship between vitamin D status and blood pressure and hypertension risk.
As reported in The Lancet Diabetes & Endocrinology, the team found that for each 10% increase in the concentration of 25(OH)D, the diastolic blood pressure and systolic blood pressure dropped by 0.29 mm Hg and 0.37 mm Hg, respectively. In addition, each 10% increase in 25(OH)D was associated with an 8.1% decrease in the likelihood of developing hypertension.
Hyppönen says the possibility that the findings were caused by chance still cannot be excluded and the results therefore need to be replicated in an independent, similarly powered study.
Hyppönen also suggests that as well as further randomised controlled trials being carried out to confirm causality, the potential clinical benefits of vitamin D supplementation should be studied: “In view of the costs and side effects associated with antihypertensive drugs, the potential to prevent or reduce blood pressure and therefore the risk of hypertension with vitamin D is very attractive.”