Skip to main content
Evidence-Based Supplement Research
Evidence-Based Supplement Research
Pillser
Search
Sign UpLog In

Vitamin B9

What does the research say about Vitamin B9?

3 health outcomes synthesised

Pillser's research synthesis covers 3 health outcomes for Vitamin B9 (folate). The strongest evidence supports its role in reducing homocysteine levels, based on 7 studies where 6 found beneficial effects at a typical dose of 1 mg/day in healthy adults and clinical populations. Evidence for cognitive function and increasing folate levels is more preliminary, each drawing from only 3 studies.

Strongest evidence: The most robust finding is for reduced homocysteine levels, supported by high-strength evidence across 7 studies (6 beneficial, 1 neutral). Effects range from small to moderate, with doses around 1 mg/day and observable results typically after 8–12 weeks. Populations studied include healthy adults, patients with coronary heart disease, type 2 diabetes, and older adults (50–65 years).

Mixed or weaker evidence: Evidence for improved cognitive function is low-strength (3 studies; 2 beneficial, 1 neutral). Effects were mixed in magnitude, and one study in schizophrenia patients with low folate found no effect at 5 mg/day, while a study in cerebral small vessel disease found benefit at 0.8 mg/day. Similarly, increased folate level has low-strength evidence (3 studies; 2 beneficial, 1 neutral), with large effects seen in patients with phenylketonuria but a neutral effect in healthy women receiving low-dose fortification.

Effective dose patterns: Where reported, studies on homocysteine reduction consistently used 1 mg/day. For other outcomes, effective doses were less uniform — cognitive function studies used 0.8 mg/day (beneficial) and 5 mg/day (no effect), while folate level studies varied by delivery method (supplementation vs. fortification).

Population insights: The strongest evidence comes from clinical populations (e.g., coronary heart disease, type 2 diabetes) and healthy adults. For cognitive outcomes, benefit was seen in patients with cerebral small vessel disease but not in schizophrenia patients with low folate. For folate levels, the largest effect was in patients with phenylketonuria, suggesting baseline status matters.

Notable caveats: The homocysteine evidence is subject to publication bias (null results less likely published), and most trials were short (4–12 weeks), leaving long-term effects undocumented. The cognitive and folate level evidence bases are small (3 studies each), making conclusions preliminary. Dose, population, and delivery method (supplement vs. fortification) appear to influence outcomes across syntheses.

Frequently asked

  • What is Vitamin B9 good for according to research?
    Research suggests Vitamin B9 (folate) is most consistently beneficial for reducing homocysteine levels — 6 of 7 studies found positive effects, with the strongest evidence coming from clinical populations and healthy adults. Evidence for improving cognitive function and increasing folate levels is preliminary, with only 2 of 3 studies showing benefit in each case.
  • What dose of Vitamin B9 is typically used in studies?
    For reducing homocysteine levels, studies consistently used a dose of 1 mg/day, with effects observed at 8–12 weeks. For cognitive function, doses ranged from 0.8 mg/day (beneficial) to 5 mg/day (no effect in one study). Folate level studies did not consistently report doses, but one used low-dose fortification that showed no effect.
  • Who benefits most from Vitamin B9?
    For homocysteine reduction, benefit was seen across healthy adults and patients with coronary heart disease, type 2 diabetes, and older adults (50–65 years). For cognitive function, benefit was observed in patients with cerebral small vessel disease but not in schizophrenia patients with low folate. For increasing folate levels, the largest effect was in patients with phenylketonuria.
  • Are there caveats or limitations in the research on Vitamin B9?
    Yes. The homocysteine evidence is subject to publication bias (null-result studies are less likely to be published or indexed), and most trials were short (4–12 weeks), so long-term effects are not well documented. Evidence for cognitive function and folate levels is weak, each based on only 3 studies, making conclusions preliminary. Dose and delivery method (supplementation vs. fortification) also influence outcomes.
  • Does Vitamin B9 help with reducing homocysteine levels?
    Yes. Across 7 studies, 6 found beneficial effects (small to moderate) of Vitamin B9 supplementation on reducing homocysteine levels, with the strongest evidence from randomized controlled trials and meta-analyses. Effects were typically seen at 1 mg/day after 8–12 weeks, though one neutral study in children with sickle cell disease suggests the effect may not generalize to pediatric populations or those with certain comorbidities.
  • Does Vitamin B9 help with cognitive function?
    The evidence is mixed and preliminary. Of 3 studies, 2 reported beneficial effects (one moderate, one small) and 1 reported no effect. Benefit was seen in patients with cerebral small vessel disease at 0.8 mg/day, but not in schizophrenia patients with low folate at 5 mg/day. The small number of studies means conclusions are not firm.

Most-studied combinations with Vitamin B9

most supplement research is combination research
Also studied with:L-Methylfolate (3), Blood Orange (2), Zinc (3), Magnesium (2), Iron (4), Vitamin B1 (2), Vitamin B2 (2), Vitamin B6 (4), Vitamin B12 (10), Vitamin D (6), Vitamin E (3), Vitamin C (2)
View Google Sheets

  • Women's Multi Gummies

    By Trace Minerals

    4.5 (15 reviews)
    In Stock
    Available From
    Available From
    MerchantPriceStockAction
    Amazon
    $-
    		Out
    iHerb
    $18.99
    		In
    Vitacost
    $18.99
    		In
    Vitamin Shoppe
    $-
    		Out

  • Extra Strength L-Methyl Folate

    By Nature's Truth

    4.7 (100 reviews)
    Out of Stock
    Available From
    Available From
    MerchantPriceStockAction
    Amazon
    $-
    		Out
    iHerb
    $16.94
    		In
    Vitacost
    $-
    		Out
    Vitamin Shoppe
    $-
    		Out

  • L-Methyl Folate

    By Best Naturals

    4.7 (62 reviews)
    In Stock
    Available From
    Available From
    MerchantPriceStockAction
    Amazon
    $-
    		Out
    iHerb
    $15.05
    		In
    Vitacost
    $15.75
    		In
    Vitamin Shoppe
    $-
    		Out

  • L-Methylfolate

    By Metabolic Maintenance

    4.5 (90 reviews)
    Out of Stock
    Available From
    Available From
    MerchantPriceStockAction
    Amazon
    $-
    		Out
    iHerb
    $63.00
    		In
    Vitacost
    $-
    		Out
    Vitamin Shoppe
    $-
    		Out

  • Brain Zone Basic

    By Divine Health

    5 (2 reviews)
    Out of Stock
    Available From
    Available From
    MerchantPriceStockAction
    Amazon
    $-
    		Out
    iHerb
    $32.68
    		In
    Vitacost
    $37.99
    		In
    Vitamin Shoppe
    $-
    		Out

  • Methyl Folate

    By Best Naturals

    4.6 (7 reviews)
    In Stock
    Available From
    Available From
    MerchantPriceStockAction
    Amazon
    $-
    		Out
    iHerb
    $17.20
    		In
    Vitacost
    $-
    		Out
    Vitamin Shoppe
    $-
    		Out
Back to top