**8. Hypertension**

Low vitamin D status has been heavily linked to an increased prevalence of hypertension. A prospective examination of 1,211 non-hypertensive men, over a 15 year follow-up period, demonstrated an inverse association between vitamin D levels and hypertension development [51].

In addition to the demonstrated link between low vitamin D levels and hypertension development, the Framingham Offspring Study suggested that low vitamin D levels may also increase the risk associated with already existing hypertension, which may substantially augment the risk of future CV events [52].

Contrary to observational evidence, randomized controlled trials of vitamin D repletion have not shown significant changes in blood pressure in vitamin D deficient individuals with prehypertension or hypertension [53, 54].

In a randomized, double blind trial involving 283 black subjects given either placebo, 1,000, 2,000, or 4,000 IU/day of vitamin D for 3 months, significant modest reductions in systolic blood pressure were seen. Systolic blood pressure decreased by 0.2 mmHg for every 1 ng/mL increase in vitamin D, but no effect on diastolic pressure was demonstrated [55].

In VITdish, another small (N = 159) randomized, double-blind, placebo-controlled trial, there was no effect of vitamin D supplementation on blood pressure or other markers of vascular health in older adults with systolic hypertension [56].

A 6 month study of vitamin D3 supplementation including patients with resistant hypertension showed similar results. Effects on left ventricular hypertrophy were also negligible, although the short follow-up may have limited this assessment [57].

In the VIDA study, with monthly high dose vitamin D supplementation, there were no significant differences between the vitamin D and placebo groups regarding incident hypertension [10].

Lastly and likewise, in the VITAL study using high daily doses of vitamin D, hypertension incidence was not significantly different in the vitamin D and placebo groups [9].
