Low Vitamin D Causes High Blood Pressure

A new genetic study has confirmed that a causal association exists between low levels of vitamin D and hypertension.

Researchers at University College London (UCL; United Kingdom) conducted a Mendelian randomization analysis of 35 previous studies involving 150,846 individuals, using single nucleotide polymorphisms (SNPs) as proxy markers to reflect vitamin D levels. The researchers examined associations of four vitamin D-related SNPs with 25 hydroxyvitamin D for validation, and with blood pressure for causal inference. All four SNPs were strongly associated with 25 hydroxyvitamin D, but none of the SNP-allele scores was associated with blood pressure or hypertension.

The results did confirm, however, earlier observational studies that showed a causal association between vitamin D levels and blood pressure, with every 10% increase in serum 25-hydroxyvitamin D concentrations associated with a 0.24 mmHg decrease in diastolic blood pressure, and an 8.1% decrease in the risk of developing hypertension. The study was presented at the European Society of Human Genetics, held during June 2013 in Paris (France).

“Our study strongly suggests that some cases of cardiovascular disease could be prevented through vitamin D supplements or food fortification,” said lead author and study presenter Vimal Karani Santhanakrishnan, PhD, of the Institute of Child Health at the UCL. “Our new data provide further support for the important nonskeletal effects of vitamin D.”

“Even with the likely presence of unobserved confounding factors, the approach we followed, known as Mendelian randomization, allows us to draw conclusions about causality because the genetic influence on disease is not affected by confounding,” added Dr. Santhanakrishnan. “To put it in simple terms, by using this approach we can determine the cause and effect and be pretty sure that we've come to the right conclusion on the subject.”

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