In Reply: Dr Prieto-Alhambra and colleagues have suggested an acute effect of vitamin D in reducing BP as an alternative mechanism by which vitamin D may have increased the risk of falls in the study by Dr Sanders and colleagues.1 They cite the study of Pfeifer et al2 conducted in 148 postmenopausal women in which daily supplementation with 800 IU of vitamin D3 plus 1200 mg per day of calcium over 8 weeks reduced systolic BP by about 7 mm Hg when compared with calcium alone. But this has not been a consistent finding. More recently, Jorde et al3 reported that oral supplementation with 40 000 IU of vitamin D3 per week, when compared with placebo, had no significant effect on BP over a 1-year period in 330 overweight and obese participants, all of whom received 500 mg per day of supplemental calcium. Thus an effect of vitamin D3 on BP has not been established. Nevertheless, hypotension-induced falls after the oral vitamin D dose in the study by Sanders et al remains a possible explanation.
Dawson-Hughes B. High-Dose Oral Vitamin D Supplementation and Risk of Falls in Older Women—Reply. JAMA. 2010;304(8):854-857. doi:10.1001/jama.2010.781-a