High-Dose Oral Vitamin D Supplementation and Risk of Falls in Older Women—Reply

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.