Supplement
Folic acid is the supplement form of vitamin B9, which the body uses to make DNA and help cells divide, especially during rapid fetal growth. People mostly look at it for pregnancy, where the evidence is strong overall, though research on infant birth weight found mixed results. That finding rests on just two studies of about 700 women, and a small review in infertile men found sperm motility improved.
Sources: PMID 22992251; PMID 26901401
- Updated
- How we grade
- 18 studies cited
- Best evidence
- Grade B
- Conditions studied
- 17
- Outcomes
- 45
- Graded outcomes
- 0924
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
General Cardiovascular Health
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Blood Pressure Mixed effect | 2 studies | 542 people | ||||
Studies that measured blood pressure | ||||||
| Arterial Stiffness No effect | NoneNo effect | 974 people | ||||
| Monocyte Chemoattractant Protein-1 | Improves (the measure goes up) | 1 study | 279 people | |||
Studies that measured monocyte chemoattractant protein-1 | ||||||
| Stroke Risk | Changes; see studies | 1 study | 115,559 people | |||
Studies that measured stroke risk | ||||||
| High-density lipoprotein (HDL) | Improves (the measure goes up) | 542 people | ||||
| Low-density lipoprotein (LDL) | Improves (the measure goes down) | 542 people | ||||
| Total cholesterol | Improves (the measure goes down) | 542 people | ||||
| Triglycerides | Improves (the measure goes down) | 542 people | ||||
| Vascular Function | Improves (the measure goes up) | 601 people | ||||
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Depression Symptoms Small Improvement | Improves (the measure goes down) | Small effect | 2 studies | 247 people | ||
Studies that measured depression symptoms | ||||||
| Schizophrenia symptoms | Improves (the measure goes down) | 2 studies | 123 people | |||
Studies that measured schizophrenia symptoms | ||||||
Low Birth Weight
- Infant Birth Weight
- Infant Death Risk: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Infant Birth Weight Mixed effect | 2 studies | 707 people | ||||
Studies that measured infant birth weight | ||||||
| Infant Death Risk | Improves (the measure goes down) | 4,002 people | ||||
Pregnancy and Delivery Health
- Infant Birth Weight
- Infant Death Risk: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Infant Birth Weight Mixed effect | 2 studies | 707 people | ||||
Studies that measured infant birth weight | ||||||
| Infant Death Risk | Improves (the measure goes down) | 4,002 people | ||||
High Blood Pressure
- Blood Pressure
- Homocysteine: improves
- Major Adverse Cardiac Events: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Blood Pressure Mixed effect | 2 studies | 5,707 people | ||||
Studies that measured blood pressure | ||||||
| Homocysteine | Improves (the measure goes down) | 7,340 people | ||||
| Major Adverse Cardiac Events | Changes; see studies | 2,057 people | ||||
Infertility
- Seminal Motility: improves
- Sperm Count: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Seminal Motility Small Improvement | Improves (the measure goes up) | Small effect | 1 study | 326 people | ||
| Sperm Count | Improves (the measure goes up) | 2,168 people | ||||
Mild Cognitive Impairment (MCI)
- Cognition: improves
- TNF-Alpha: improves
- Interleukin 6: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cognition Small Improvement | Improves (the measure goes up) | Small effect | 1 study | 823 people | ||
| TNF-Alpha | Improves (the measure goes down) | 2 studies | 408 people | |||
Studies that measured tnf-alpha
| ||||||
| Interleukin 6 | Improves (the measure goes down) | 408 people | ||||
Metabolic Health
- C-Reactive Protein (CRP): improves
- TNF-Alpha: improves
- Serum Folate: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| C-Reactive Protein (CRP) Small Decrease | Improves (the measure goes down) | Small effect | 1,482 people | |||
| TNF-Alpha | Improves (the measure goes down) | 2 studies | 962 people | |||
Studies that measured tnf-alpha
| ||||||
| Serum Folate | Improves (the measure goes up) | 1 study | 2,341 people | |||
Studies that measured serum folate | ||||||
| Interleukin 6 | Improves (the measure goes down) | 1,021 people | ||||
Metabolic Syndrome
- C-Reactive Protein (CRP): improves
- TNF-Alpha: improves
- Interleukin 6: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| C-Reactive Protein (CRP) Small Decrease | Improves (the measure goes down) | Small effect | 321 people | |||
| TNF-Alpha | Improves (the measure goes down) | 2 studies | 127 people | |||
Studies that measured tnf-alpha
| ||||||
| Interleukin 6 | Improves (the measure goes down) | 191 people | ||||
Premature Birth
- Infant Birth Weight
- Infant Death Risk: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Infant Birth Weight Mixed effect | 2 studies | 5,332 people | ||||
Studies that measured infant birth weight | ||||||
| Infant Death Risk | Improves (the measure goes down) | 4,002 people | ||||
Schizophrenia
- Cognition: improves
- Depression Symptoms: improves
- Schizophrenia symptoms: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cognition Small Improvement | Improves (the measure goes up) | Small effect | 1 study | 55 people | ||
| Depression Symptoms | Improves (the measure goes down) | 2 studies | 123 people | |||
Studies that measured depression symptoms | ||||||
| Schizophrenia symptoms | Improves (the measure goes down) | 2 studies | 340 people | |||
Studies that measured schizophrenia symptoms | ||||||
Type 2 Diabetes
- HbA1c
- Homocysteine: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| HbA1c No effect | NoneNo effect | 1 study | 142 people | |||
| Homocysteine | Improves (the measure goes down) | 183 people | ||||
Weight Loss & Maintenance
- Body Mass Index (BMI)
- Weight: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Body Mass Index (BMI) No effect | NoneNo effect | 1 study | 409 people | |||
| Weight | Improves (the measure goes down) | 409 people |
Infant Health
- Cleft lip/palate risk
- Neural tube defect risk: improves
- Congenital heart defect risk: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cleft lip/palate risk No effect | NoneNo effect | 6,708 people | ||||
| Neural tube defect risk | Improves (the measure goes down) | 1 study | 6,708 people | |||
| Congenital heart defect risk | Changes; see studies | 6,708 people |
Stroke
- Stroke Risk: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Stroke Risk | Changes; see studies | 1 study | 115,559 people |
Epilepsy
- Seizure Frequency: changes; see studies
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Seizure Frequency | Changes; see studies | 1 study | 75 people |
Memory Improvement
- Memory: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Memory | Improves (the measure goes up) | 1 study | 641 people |
What the published studies found
4 automated readings
LDL cholesterol
The best available review (2026, 36 studies) found little or no difference in LDL cholesterol. That review studied adults with hyperhomocysteinemia. 3 of the 5 studies read agree; 2 found an improvement. The evidence is limited.
5 studies counted of 9 read: 3 reviews and 2 trials (68 people in the trials).
- Systematic review, 2026; 36 studies; adults with hyperhomocysteinemia: no clear difference (the review the verdict rests on).
low-density lipoprotein cholesterol (LDL-C) (WMD = - 3.64)
Efficacy and safety of folic acid on homocysteine and cardiovascular surrogate biomarkers in hyperhomocysteinemia: a systematic review and meta-analysis of RCTs - Meta-analysis, 2022; 34 studies, 21,787 people: no clear difference.
did not affect serum concentrations of LDL
Beneficial effects of folic acid supplementation on lipid markers in adults: A GRADE-assessed systematic review and dose-response meta-analysis of data from 21,787 participants in 34 randomized controlled trials - Meta-analysis, 2018; 13 studies; patients with metabolic diseases: no clear difference.
LDL-cholesterol (SMD -0.14; 95% CI, -0.55, 0.28).
The effects of folate supplementation on lipid profiles among patients with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials - Randomised trial, 2025; 48 people; nigerian children with nephrotic syndrome: improves.
The intervention group also had greater reductions than the control group in total cholesterol (-13.2 …
Vitamin B Supplementation and Homocysteine Reduction in Nigerian Children with Nephrotic Syndrome: A Randomized Controlled Trial - Randomised trial, 2005; 20 people; healthy postmenopausal women: improves.
improvement in other atherosclerotic indexes, such as cholesterol/HDL and LDL/HDL ratios
L-folic acid supplementation in healthy postmenopausal women: effect on homocysteine and glycolipid metabolism
- Systematic review, 2026; 36 studies; adults with hyperhomocysteinemia: no clear difference (the review the verdict rests on).
Cardiovascular events
The studies disagree. A Cochrane review (2017, 15 studies, 71,422 people) found little or no difference in cardiovascular events, while 1 of the 7 studies read found an improvement. The evidence is very weak.
7 studies counted of 10 read: 7 reviews.
- Meta-analysis, 2017; 15 studies, 71,422 people; patients with and without pre-existing cardiovascular disease: no clear difference (the review the verdict rests on).
no differences in effects of homocysteine-lowering interventions on myocardial infarction
Homocysteine-lowering interventions for preventing cardiovascular events - Meta-analysis, 2026; 9 studies, 23,638 people: no clear difference.
No significant effects were observed for cardiovascular events
A Meta-Analysis of the Effects of Homocysteine-Lowering Therapy on Chronic Kidney Disease - Systematic review, 2025; 45 studies, 96,962 people: improves.
modest reduction on overall CVD (RR = 0.95
Efficacy of folic acid supplementation in the prevention of cardiovascular disease - a systematic review and meta-analysis of randomized controlled trials - Meta-analysis, 2016; 6 studies, 2,452 people; patients with end-stage kidney disease: no clear difference.
little or no effect on cardiovascular mortality
Interventions for lowering plasma homocysteine levels in dialysis patients - Meta-analysis, 2012; 11 studies, 10,951 people; people with kidney disease: no clear difference.
did not prevent cardiovascular events (relative risk 0.97
The effect of folic acid based homocysteine lowering on cardiovascular events in people with kidney disease: systematic review and meta-analysis - Meta-analysis, 2010; 8 studies, 37,485 people; individuals at increased risk of cardiovascular disease: no clear difference.
no significant effects on vascular outcomes
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 - Meta-analysis, 2010: no clear difference.
FA supplementation did not affect primary cardiovascular clinical end points
Meta-analysis of folic acid supplementation trials on risk of cardiovascular disease and risk interaction with baseline homocysteine levels
- Meta-analysis, 2017; 15 studies, 71,422 people; patients with and without pre-existing cardiovascular disease: no clear difference (the review the verdict rests on).
Memory
The studies read are too weak to tell whether Folic Acid (Vitamin B9) changes memory. The strongest review read studied people with mild cognitive impairment. The evidence is very weak.
11 studies counted of 11 read: 9 reviews and 2 trials (315 people in the trials).
- Meta-analysis, 2018; 5 studies, 879 people; people with mild cognitive impairment: unclear: evidence too weak to tell (the review the verdict rests on).
probably little or no effect of B vitamins
Vitamin and mineral supplementation for preventing dementia or delaying cognitive decline in people with mild cognitive impairment - Systematic review, 2026: improves.
folic acid+DHA, and the DHA+EPA+vitamin E+tryptophan+melatonin were all effective in augmenting memory
Nutritional supplements and cognition in healthy aging and mild cognitive impairment patients: a systematic review and network meta-analysis - Systematic review, 2022; 9 studies, 641 people: no clear difference.
did not significantly change memory score compared to placebo
Does folic acid supplementation have a positive effect on improving memory? A systematic review and meta-analysis of randomized controlled trials - Systematic review, 2018; 38 studies; adults with normal cognition or MCI: no clear difference.
improvements in performance on some objectively measured memory tests
Over-the-Counter Supplement Interventions to Prevent Cognitive Decline, Mild Cognitive Impairment, and Clinical Alzheimer-Type Dementia: A Systematic Review - Systematic review, 2018; 16 studies: improves.
improvements in performance, particularly in memory
Effect of dietary interventions in mild cognitive impairment: a systematic review - Meta-analysis, 2014; 5 studies; individuals with mild cognitive impairment or Alzheimer's disease: improves.
moderate beneficial effects of vitamins B supplementation on memory
Efficacy of vitamins B supplementation on mild cognitive impairment and Alzheimer's disease: a systematic review and meta-analysis - Meta-analysis, 2010; 9 studies, 2,835 people: no clear difference.
standardized mean differences were 0.01 (95% CI, -0.08 to 0.09)
Effect of folic acid, with or without other B vitamins, on cognitive decline: meta-analysis of randomized trials - Systematic review, 2008; 8 studies; healthy elderly and demented people: unclear: evidence too weak to tell.
memory storage (WMD 0.14, 95% CI 0.04 to 0.24, P = 0.006)
Folic acid with or without vitamin B12 for the prevention and treatment of healthy elderly and demented people - Systematic review, 2003; 4 studies; elderly healthy and demented people: no clear difference.
found no benefit from folic acid with or without vitamin B12 in comparison with placebo
Folic acid with or without vitamin B12 for cognition and dementia - Randomised trial, 2016; 104 people; middle-aged and elderly patients with hyperhomocysteinemia: improves.
significantly increased only for the vitamin B group
B vitamin supplementation improves cognitive function in the middle aged and elderly with hyperhomocysteinemia - Randomised trial, 2002; 211 people; healthy younger, middle-aged and older women: improves.
significant positive effect on some measures of memory performance
Short-term folate, vitamin B-12 or vitamin B-6 supplementation slightly affects memory performance but not mood in women of various ages
- Meta-analysis, 2018; 5 studies, 879 people; people with mild cognitive impairment: unclear: evidence too weak to tell (the review the verdict rests on).
Mood
The studies disagree. A Cochrane review (2008, 8 studies) found little or no difference in mood, while 2 of the 4 studies read found an improvement. The evidence is very weak.
4 studies counted of 9 read: 4 reviews.
- Systematic review, 2008; 8 studies; healthy elderly and demented people: no clear difference (the review the verdict rests on). Folic acid with or without vitamin B12 for the prevention and treatment of healthy elderly and demented people
- Meta-analysis, 2022; 15 studies, 26,275 people; pregnant women: improves.
overall odds ratio was 0.742 (95% CI: (0.647-0.852))
Continuous supplementation of folic acid in pregnancy and the risk of perinatal depression-A meta-analysis - Meta-analysis, 2020; 16 studies, 1,520 people; schizophrenia, bipolar disorder, major depressive disorder: improves.
significantly superior to placebo in improving depressive symptoms
Adjunctive folate for major mental disorders: A systematic review - Systematic review, 2003; 4 studies; elderly healthy and demented people: no clear difference. Folic acid with or without vitamin B12 for cognition and dementia
Key findings
- Blood Pressure
- Depression SymptomsImproves (the measure goes down)
- Infant Birth Weight
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- Grade B
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Studies cited
18 studies from PubMed
- Folate for depressive disorders
- Enhancement of recovery from psychiatric illness by methylfolate
- Folic acid/methylfolate for the treatment of psychopathology in schizophrenia: a systematic review and meta-analysis.
- Biomarker responses to folic acid intervention in healthy adults: a meta-analysis of randomized controlled trials.
- The Effects of Folic Acid Supplementation on Pro-inflammatory Mediators: a Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials.
- Effect of folic acid supplementation on plasma total homocysteine levels and glycemic control in patients with type 2 diabetes: a systematic review and meta-analysis.
- Vitamins for epilepsy.
- Effect of folate intake on health outcomes in pregnancy: a systematic review and meta-analysis on birth weight, placental weight and length of gestation.
- Folic acid supplementation in pregnancy to prevent preterm birth: a systematic review and meta-analysis of randomized controlled trials.
- Effects and safety of periconceptional oral folate supplementation for preventing birth defects.
- The effects of folate supplementation on lipid profiles among patients with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials.
- The Effect of Folic Acid Supplementation on Endothelial Function and Arterial Stiffness Markers in Adults: A Systematic Review and Meta-Analysis.
- Folic acid supplementation for stroke prevention: A systematic review and meta-analysis of 21 randomized clinical trials worldwide.
- Beneficial effects of folic acid on inflammatory markers in the patients with metabolic syndrome: Meta-analysis and meta-regression of data from 511 participants in 10 randomized controlled trials.
- The effect of folic acid supplementation on body weight and body mass index: A systematic review and meta-analysis of randomized controlled trials.
- A Meta-Analysis of Folic Acid in Combination with Anti-Hypertension Drugs in Patients with Hypertension and Hyperhomocysteinemia.
- Does folic acid supplementation have a positive effect on improving memory? A systematic review and meta-analysis of randomized controlled trials
- Effects of folic acid supplementation on cognitive function and inflammation in elderly patients with mild cognitive impairment: A systematic review and meta-analysis of randomized controlled trials.