High-dose vitamin D supplementation ups risk of falls with fractures in older adults

Higher doses of vitamin D supplementation, ranging from 1,000–4,000 IU/day, may heighten the risk of first-time falls with fractures in older adults, a recent study has found.

Researchers conducted a secondary analysis of the STURDY* trial, looking at the effect of four doses of vitamin D3 supplementation in 688 older participants (aged ≥70 years, 43.6 percent women): 200 (control), 1,000, 2,000, and 4,000 IU/day. Outcomes were repeat falls and falls that were consequential, leading to injuries, emergency care, or fractures. Fall location (indoor or outdoor) was also recorded.

A total of 1,477 falls were reported over the entire follow-up period, most of which (53 percent) were at least the third time such an incident had occurred; 29 percent were first falls. Thirty-one falls led to injuries, while 124 necessitated emergency care. There were 647 and 614 incidents that were deemed consequential and injurious, respectively.

Pooling all higher doses of vitamin D supplementation (1,000–4,000 IU/day) showed a risk estimate for first falls resulting in fractures that was more than twice as high as in controls (hazard ratio [HR], 2.66, 95 percent confidence interval [CI], 1.18–6.00; unadjusted p=0.019). Adjusting for confounders attenuated its significance (p=0.114).

In terms of fall timing and location, participants on the 1,000-IU/day vitamin D3 intervention saw a 39-percent lower risk of first-time outdoor falls relative to controls (HR, 0.61, 95 percent CI, 0.38–0.97; unadjusted p=0.036). The 2,000-IU/day dose had a slightly stronger effect, reducing such a risk by 40 percent (HR, 0.60, 95 percent CI, 0.38–0.97; unadjusted p=0.037).

However, multiple adjustments for confounders ultimately attenuated these interactions (p=0.222 for both).

*Study to understand fall reduction and vitamin D in you