EvidenceHealthVitaminsSupplementsVitamin D
Annual high-dose vitamin D3 in older women: increased risk of falls and fractures
- Study type:
- Randomised, double-blind, placebo-controlled trial of very high annual bolus vitamin D3 in community-dwelling older women.
- Topic:
- Vitamin D dosing and bone health
- Added:
- 2026-04-24
- Status:
- published
Strength of evidence
Moderate
Source
Sanders KM et al. Annual high-dose oral vitamin D and falls and fractures in older women: a randomized controlled trial. JAMA. 2010;303(18):1815–1822.
Open original studyCommunity-dwelling women aged ≥70 years at increased fracture risk received either a **single annual oral dose of 500,000 IU vitamin D3** or placebo for 3–5 years. Unexpectedly, the vitamin D group had a **higher rate of falls and fractures** than the placebo group, especially in the months following each dose. This well-conducted RCT with hard endpoints provides **moderate-quality evidence** that very high, infrequent bolus dosing of vitamin D3 can be harmful in older women, contradicting the idea that "more vitamin D is always better."
Key findings
- Participants: >2,000 community-dwelling women aged ≥70 years, considered at increased risk of fracture.
- Intervention: annual single **500,000 IU** oral dose of vitamin D3 vs matching placebo.
- Follow-up: 3–5 years.
- **Falls:** higher incidence in the vitamin D group compared with placebo.
- **Fractures:** also higher in the vitamin D group, particularly in the first 3 months after dosing.
- No evidence that this regimen reduced fractures; instead, it appeared to **increase** risk.
Background
- Vitamin D has been widely promoted to improve bone health and prevent fractures in older adults. To maximise adherence, some clinicians and researchers tested **large, infrequent bolus doses** (e.g. once per year) rather than daily dosing.
- This trial examined whether giving a **single 500,000 IU dose of vitamin D3 once a year** to older women would reduce falls and fractures – and instead found the opposite.
Methods
- **Population:** More than 2,000 community-dwelling women aged ≥70 years, considered at increased risk for fracture.
- **Design:** Randomised, double-blind, placebo-controlled. Intervention group: **500,000 IU oral vitamin D3** once per year. Control group: matching placebo.
- **Duration:** 3–5 years of follow-up.
- **Endpoints (hard):** Number of falls, Number of fractures (including hip and non-vertebral fractures).
Results
- Women in the vitamin D group experienced: **More falls** than those in the placebo group. **More fractures**, especially in the first 3 months after each high-dose administration.
- The trial did **not** show any protective effect of this dosing regimen on fractures.
- The timing pattern (increased events soon after dosing) suggested a potential transient destabilising effect on neuromuscular function or bone turnover.
Interpretation
- Contrary to expectations, very high **annual bolus doses** of vitamin D3 (500,000 IU) in older women: **increased** the risk of falls and fractures, particularly in the months immediately following the dose.
- From the WorthDay perspective: This RCT uses **hard, clinically meaningful endpoints** (falls and fractures) with clear differences between groups, which justifies a **moderate evidence** rating for harm under the specific regimen tested.
- It challenges the assumption that: "If some vitamin D is good, a lot in one go must be even better."
- It also highlights that **dose and dosing schedule** matter; vitamin D is not a risk-free neutral substance at all doses and patterns.
Limitations
- Results apply specifically to **annual mega-bolus dosing (500,000 IU)** in older women; they cannot be directly generalised to lower daily doses or other populations.
- Mechanisms behind the increased falls and fractures were not fully elucidated.
- The study does not tell us whether moderate, well-targeted vitamin D dosing in truly deficient individuals would be beneficial.
WorthDay perspective
- S0054 is a clear warning signal within the vitamin D story: certain **high-dose, infrequent regimens can cause harm**, even when the substance is widely marketed as a benign "vitamin".
- Together with S0053, it argues strongly against: simplistic "vitamin D is always good" narratives, aggressive high-dose supplementation strategies in people who are not clearly deficient.
- For WorthDay users: vitamin D supplements should not be seen as a risk-free, automatic upgrade, and any high-dose regimen – especially in older adults – should be approached with great caution and medical supervision.
Permalink: https://www.worth-day.com/science-compass/s0054-annual-high-dose-vitamin-d3-in-older-women-increased-risk
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