B vitamins (folate, B12, B6)
Lower homocysteine. Lowering it did not prevent infarctions in the outcome trials.
Order of magnitude
The folate, B12 and B6 doses used in the lowering trials.
This is the database's clearest case of a marker that moves and an outcome that does not.
Effects in detail
Each row is a directed edge from our database, with range, latency, evidence grade and the condition under which it applies at all.
| Marker | Effect | Latency | Mode of action | Outcome | Evidence | Condition | Sources |
|---|---|---|---|---|---|---|---|
| Diastolic blood pressure | helps. Lowers -0.24 mmHg confidence interval of the estimate, not the range one person can expect Twenty-two randomised trials in 41,633 participants give a systolic reduction of 1.10 mmHg (95 % CI -1.93 to -0.28) and a diastolic reduction of 0.24 mmHg with folic acid supplementation. outcome_proven is no: the same intervention was tested against hard outcomes in 71,422 people and did not reduce myocardial infarction or death, although it did reduce stroke by 10 %. | not specified | chronic | no | Evidence grade A | applies regardless of the starting value | |
| Systolic blood pressure | helps. Lowers -1.10 mmHg confidence interval of the estimate, not the range one person can expect Twenty-two randomised trials in 41,633 participants give a systolic reduction of 1.10 mmHg (95 % CI -1.93 to -0.28) and a diastolic reduction of 0.24 mmHg with folic acid supplementation. outcome_proven is no: the same intervention was tested against hard outcomes in 71,422 people and did not reduce myocardial infarction or death, although it did reduce stroke by 10 %. | not specified | chronic | no | Evidence grade A | applies regardless of the starting value | |
| HOMA-IR | helps. Lowers -0.40 HOMA-IR units confidence interval of the estimate, not the range one person can expect Across 24 randomised trials, folic acid lowered HOMA-IR by 0.40 (95 % CI -0.70 to -0.09), fasting blood glucose by 2.17 mg/dL and fasting insulin by 1.63 pmol/L. outcome_proven 'no': for this intervention the outcome trials exist and are null. | not specified | chronic | no | Evidence grade B | applies regardless of the starting value |
What this measure costs
Counteracting effects of the same measure.
No counteracting effect is on file for this measure. That does not mean there is none, only that we found no defensible edge.
Moves without implying progress
Informational or no established effect: the marker moves or was checked, and that is not progress.
| Marker | Effect | Latency | Mode of action | Outcome | Evidence | Condition | Sources |
|---|---|---|---|---|---|---|---|
| HbA1c | checked, nothing happens. No established effect A dose-response meta-analysis of 24 randomised trials found no effect of folic acid on HbA1c (-0.27 percentage points, 95 % CI -0.73 to +0.18, p = 0.246), although fasting glucose, fasting insulin and HOMA-IR did improve slightly. outcome_proven is no rather than unclear because for B vitamins the outcome question has actually been answered: 15 randomised trials in 71,422 people found no reduction in myocardial infarction or death. | not specified | chronic | no | Evidence grade A | applies regardless of the starting value | |
| Homocysteine | moves, and does not count. Lowers -25.0 % confidence interval of the estimate, not the range one person can expect Individual data on 1114 people in 12 randomised trials: folic acid lowered homocysteine by 25 % (95 % CI 23 to 28), vitamin B12 added a further 7 % (3 to 10) and vitamin B6 added nothing. outcome_proven is 'no', and that is the point of including this marker at all. | not specified | chronic | no | Evidence grade A | applies regardless of the starting value |
Sources
Full details of every study the rows above rely on.
Folic Acid Supplementation Improves Glycemic Control for Diabetes Prevention and Management: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials
Asbaghi et al. · Nutrients · 2021 · Meta-analysis
Folic acid supplementation and blood pressure: a GRADE-assessed systematic review and dose-response meta-analysis of 41,633 participants
Asbaghi et al. · Critical Reviews in Food Science and Nutrition · 2023 · Meta-analysis
Effects of lowering homocysteine levels with B vitamins on cardiovascular disease, cancer, and cause-specific mortality: meta-analysis of 8 randomized trials involving 37,485 individuals
Clarke et al. (B-Vitamin Treatment Trialists' Collaboration) · Archives of Internal Medicine · 2010 · Meta-analysis
Lowering blood homocysteine with folic acid-based supplements: meta-analysis of randomised trials
Clarke R (Homocysteine Lowering Trialists' Collaboration) · Indian Heart Journal · 2000 · Meta-analysis
Homocysteine-lowering interventions for preventing cardiovascular events
Marti-Carvajal et al. (Cochrane) · Cochrane Database of Systematic Reviews · 2017 · Meta-analysis