Calcium for Bone Fracture
The evidence on calcium for fracture prevention is genuinely conflicting and population-dependent: it does little or nothing for healthy community-dwelling adults, and any meaningful benefit is largely confined to calcium combined with vitamin D in frail, institutionalized, or low-intake elderly people. For most people, calcium supplements are not a reliable way to prevent fractures.
Why this grade7-layer evidence engine
This is graded weak (C) and flagged as disputed because high-quality trials point in opposite directions depending on who is studied. In free-living older adults the signal is essentially null: a large government-funded meta-analysis (PMID 29279934, n=51,145) found combined calcium plus vitamin D did not lower hip fracture (RR 1.09), and the Women's Health Initiative RCT (PMID 16481635, n=36,282) found no benefit in its main analysis (hip-fracture HR 0.88, not significant), with benefit emerging only among adherent women and those 60 and older.
The countervailing evidence comes mostly from higher-risk groups and combined supplementation. The landmark Chapuy trial (PMID 1331788) cut hip fractures ~43% in institutionalized, low-intake, vitamin-D-deficient elderly women, and meta-analyses report reductions for calcium plus vitamin D (PMID 31860103: hip RR 0.84; PMID 26510847: hip RR 0.70). Notably, the largest benefit (PMID 26510847) is industry/advocacy-funded, calcium alone shows the weakest effect, and WHI also recorded more kidney stones (HR 1.17).
Regulators and clinics echo this restraint. The FDA permits only a qualified claim that adequate calcium with vitamin D 'may reduce the risk of osteoporosis,' the UK NHS says a balanced diet should supply calcium and warns high doses can cause stomach upset, the WHO recommends supplementation only for low-intake pregnant women, and Mayo Clinic notes supplements have a 'modest and limited' effect, favoring diet and exercise. Together these put calcium at weak, conditional evidence rather than a general fracture-prevention recommendation.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.485
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 1 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status