Can vitamin D lower blood pressure?

A new study from Scotland suggests that vitamin D supplementation does not lower blood pressure in patients with hypertension. Experts criticize the study’s validity.

In the randomized controlled trial, 159 patients (average age 77) with a common type of high blood pressure (isolated systolic hypertension) were given vitamin D supplementation (100,000 IU) or a placebo every three months for one year (1). The study results showed that the patients receiving vitamin D had no significant decrease in blood pressure and no improvement in other measures of cardiovascular health when compared to the placebo group.

The researchers commented that these findings are disappointing because low levels of vitamin D have been associated with hypertension, and there was a hope that vitamin D supplementation would help correct this condition known to be cause of heart attack and stroke. Being able to modify that risk with a vitamin, which has no side effects and is low in cost, would be a fabulous advance for cardiovascular disease prevention. However, it still might be possible that vitamin D supplementation could have beneficial effects on cardio-vascular health via non-blood-pressure effects.

Experts criticized that the study was very small and there would have had to be a very large drop in blood pressure to detect any effect. In addition, the trial participants were not ethnically diversity, and the way blood pressure was measured was not consistent. If vitamin D levels are low, one should try to replete them, acknowledging that it is not certain how much benefit this does.

1. Giovannucci E. Cholecalciferol treatment in older patients with isolated systolic hypertension.
   JAMA Intern Med. Published online August 2013.