14 Aug Vitamin D Supplementation: No Significant Blood Pressure Reduction

MedicalResearch.com Interview with: Miles D. Witham, PhD Aging and Health, University of Dundee, Dundee, United Kingdom MedicalResearch.com: What are the main findings of the study? Answer: We gave high dose vitamin D3 (100,000 units) or placebo every 3 months to people aged 70 or over, who all had isolated systolic hypertension (ISH). The main focus of the trial was to test whether vitamin D supplementation could reduce blood pressure in this group of patients – this pattern of blood pressure, whether the systolic (top number) is high, and the diastolic (bottom number) is normal, is very common in older people. Previous studies have suggested a link between low vitamin D levels and higher blood pressure, but no trial has yet tested this idea in older patients with ISH. Despite the treatment causing a significant increase in circulating vitamin D levels, we saw no significant reduction in blood pressure with vitamin D supplementation, despite the trial running for a year. We tested whether certain groups might still benefit – e.g. those with very high blood pressure or very low vitamin D levels, but even these groups did not show a reduction in blood pressure. We also tested whether vitamin D supplementation reduced the health and stiffness of arteries – both important predictors of future heart attack or stroke. Unfortunately, vitamin D did not affect these measures either, and didn’t reduce cholesterol or glucose levels. On the more positive side, vitamin D supplements did appear safe, and the number of falls in the vitamin D group was slightly lower than in those people who received placebo. This is reassuring, as an earlier study (Sanders et al) had suggested that very high doses of vitamin D might make falls more likely, in contrast to previous low dose studies that show a protective effect of vitamin D against falls.