Lower blood levels of 25-hydroxyvitamin D, a protein that provides a measure of vitamin D in the blood, is independently associated with an increased risk of developing high blood pressure.   Studies have shown 25(OH)D levels and skin exposure to UVB radiation are associated with lower blood pressure, but definitive studies are limited. Researchers from America conducted a studied 1,484 healthy women. Cases were compared with a placebo group with a similar age, race and other features. The subjects' average age was 43 years.   It was found that the patients had a significantly lower average blood level of 25(OH)D than the controls (25.6 ng/mL vs 27.3). Compared to women with the highest 25(OH)D levels, those with the lowest levels had a 66 percent increased risk of high blood pressure.   Overall, 66 percent of the women had vitamin D deficiency. In subjects who were vitamin D-deficient, the odds of developing high blood pressure were increased by 47 percent compared to those with adequate levels. Given that 68 percent of women were vitamin D deficient, the population risk attributable to vitamin D deficiency is 4.5 new cases of high blood pressure per 1,000 young women annually. If this association is causal, then vitamin D deficiency may account for 24 percent of all new cases of high blood pressure developing among young women every year.   However, the researchers call for randomised trials to determine whether vitamin D supplementation could reduce blood pressure.  
Hypertension
November 2008