Vitamin B12 for Homocysteine
Verdict: Counter-Evidence
Across 5 PubMed studies, the evidence for Vitamin B12 in Homocysteine grades Tier D — counter-evidence. High-quality evidence indicates it is not effective (or is harmful) for this use.
D 🔴 D Counter-Evidence Counter-Evidence
Why this grade7-layer evidence engine
⚖️
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditableRaw score 0.50
D
C
B
A
S
← counter-evidence / ineffectiveeffective / strong evidence →
Final grade
D · Counter-Evidence
Confidence
82%
Highly consistent evidence
Evidence level
E1
Cochrane high-quality SR/MA
▸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 = 0.503
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高品質 SR/MA 顯示 positive (2 篇 > 0 negative)
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status
PubMed studies (5)L2 · primary research & systematic reviews
Homocysteine-lowering interventions for preventing cardiovascular events
Finding: Across 15 RCTs (71,422 participants), homocysteine-lowering B vitamins (B6/B9/B12) showed no effect on myocardial infarction (RR 1.02, 95% CI 0.95-1.10) or all-cause death (RR 1.01, 95% CI 0.96-1.06), with only a small reduction in stroke (RR 0.90, 95% CI 0.82-0.99).
View on PubMed A comprehensive review and meta-regression analysis of randomized controlled trials examining the impact of vitamin B12 supplementation on homocysteine levels
Finding: Pooled across 21 RCTs (1,625 participants), vitamin B12 supplementation significantly lowered plasma homocysteine by a weighted mean difference of -4.15 umol/L (95% CI -4.86 to -3.45; P < 0.001), with larger effects at doses >500 ug/day, durations >=12 weeks, and with hydroxocobalamin.
View on PubMed Combined B-vitamin supplementation on homocysteine and vascular outcomes in coronary heart disease: a meta-analysis
Finding: Across 13 RCTs (14,539 participants), combined B vitamins lowered homocysteine (mean difference -2.36 umol/L, 95% CI -3.09 to -1.62, P < 0.01) but produced no difference in major cardiovascular events (p = 0.78) or CV mortality (RR 0.96, 95% CI 0.85-1.07, p = 0.44).
View on PubMed Impact of supplementation with vitamins B6, B12, and/or folic acid on the reduction of homocysteine levels in patients with mild cognitive impairment: A systematic review
Finding: Across 8 primary studies (1,140 participants), all reported statistically significant homocysteine reductions with B6/B12/folic acid, with a mean decline of 31.9% in intervention arms versus a 0.7% increase in controls.
View on PubMed Effects of B Vitamins on Homocysteine Lowering and Thrombotic Risk Reduction-A Review of Randomized Controlled Trials Published Since January 1996
Finding: This narrative review of RCTs concludes B vitamins effectively reduce plasma homocysteine, but that the evidence on thrombosis prevention is inconsistent and whether supplementation confers clinical benefit remains inconclusive (no pooled effect estimate reported).
View on PubMed Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …
L4a US FDA
Supportive
NUTRIENT SUPPLEMENT source↗
L4b EU EFSA
Supportive
a cause and effect relationship has been established source↗
L4c UK NHS
Supportive
Adults aged 19 to 64 need about 1.5 micrograms a day of vitamin B12. source↗
L4d TW TFDA / 衛福部
Supportive
維生素B12之足夠攝取量(AI)成人為每日2.4微克 source↗
L4e WHO
Supportive
Vitamin B12 or folate supplementation during pregnancy is not recommended as an intervention to improve maternal and infant health outcomes source↗
L5a NIH Office of Dietary Supplements
Supportive
Vitamin B12 supplementation appears to have no beneficial effect on performance in the absence of a nutritional deficit. source↗
L5b Mayo Clinic
Cautious
Vitamin B-12 and other B vitamins may help lower homocysteine levels. However, researchers haven't found that lowering homocysteine levels lowers the risk of heart and blood vessel disease. source↗
L5c Cleveland Clinic
Supportive
Vitamin B12, vitamin B6 and vitamin B9 (folate) break down homocysteine to generate other chemicals your body needs. ... If you have high homocysteine levels, your healthcare provider may recommend taking supplements of: Vitamin B6, Vitamin B12, Folic acid (the human-made form of folate). But increasing your vitamin intake alone doesn't reduce your risk of heart disease. source↗
L5d Harvard Health
Cautious
Homocysteine can be lowered easily and inexpensively with a trio of B vitamins — B6, B12, and folic acid. ... Lowering homocysteine doesn't mean much unless those reduced levels translate into reduced risk for the problems that elevated levels are thought to cause. source↗
L5e Specialty Society (condition-mapped)
Cautious
Recent guidelines from the European Society of Cardiology (ESC) and the American Heart Association (AHA) support the view that homocysteine should be regarded not as an isolated therapeutic target, but rather as a modifiable biomarker within a comprehensive cardiometabolic context. Current guidelines, such as the American Heart Association (AHA), do not recommend neither B-vitamin supplementati… source↗