Supplement

B Vitamins

B vitamins are a family of eight water-soluble nutrients, including thiamine, folate and B12, that help cells turn food into energy and keep nerves and blood healthy. People most often look at them for support during recovery from alcohol use disorder, since heavy drinking depletes these vitamins, especially thiamine, and the evidence for this use is strong. Folic acid lowered homocysteine, but large reviews found no change in heart disease events or general cognition.

Updated 30 September 2026
How we grade
6 studies cited

Best evidence: Grade A
Conditions studied: 8
Outcomes: 8
Graded outcomes: 1043

Evidence by condition

Strong
Moderate
Limited
Very limited

8 conditions

Homocysteine Levels

Homocysteine Levels: outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Plasma Homocysteine Folic acid 0.65-10mg/d ± B12/B6 reduces homocysteine 25-50%	Improves (the measure goes down)	Large effect		5,000 people

Stroke

Stroke: outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Stroke Risk Meta-analysis: RR 0.93 (0.86-1.00, p=0.04); benefit with ≥3 years follow-up, no folate fortification	Improves (the measure goes down)	Small effect		47,921 people

Mild Cognitive Impairment (MCI)

Cognitive Decline: improves

Mild Cognitive Impairment (MCI): outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cognitive Decline Benefits in MCI patients with high homocysteine: improved MMSE, episodic memory, slowed atrophy	Improves (the measure goes down)	Moderate effect		500 people

Stress

Perceived Stress: improves

Stress: outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Perceived Stress Meta-analysis: SMD 0.23 (0.02-0.45, p=0.03) benefit for stress	Improves (the measure goes down)	Small effect		958 people

Depression Adjunct Therapy

Treatment Response: improves

Depression Adjunct Therapy: outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Treatment Response B12 + SSRI improved outcomes in depressed patients with low-normal B12; stroke survivors showed lower depression risk	Improves (the measure goes up)	Moderate effect		200 people

Cardiovascular Disease

CVD Events/Mortality

Cardiovascular Disease: outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	CVD Events/Mortality Meta-analysis: RR 0.98 (0.94-1.03) for CVD; no effect on CHD, MI, or mortality despite homocysteine lowering		NoneNo effect		47,921 people

Cognition General Population

Cognitive Function

Cognition General Population: outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cognitive Function Meta-analysis: no benefit in general population despite up to 7 years of supplementation		NoneNo effect		22,000 people

Depression

Depressive Symptoms

Depression: outcomes studied for B Vitamins
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Depressive Symptoms Meta-analysis: SMD 0.15 (-0.01-0.32, p=0.07) - trend but not significant		NoneNo effect		568 people

Key findings

Plasma HomocysteineImproves (the measure goes down)
Stroke RiskStrokeImproves (the measure goes down)
Cognitive DeclineMild Cognitive Impairment (MCI)Improves (the measure goes down)

Safety notes in the studies

B12 + SSRI improved outcomes in depressed patients with low-normal B12; stroke survivors showed lower depression risk

Shop the evidence-backed picks

Third-party tested B Vitamins products, in the forms the graded studies used where we can match them.

Grade A

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Studies cited

6 studies from PubMed

B Vitamins and One-Carbon Metabolism: Implications in Human Health and DiseaseNutrients, 2020 · PMID 32961717
A Systematic Review and Meta-Analysis of B Vitamin Supplementation on Depressive Symptoms, Anxiety, and Stress: Effects on Healthy and 'At-Risk' IndividualsNutrients, 2019 · PMID 31527485
Effects of homocysteine lowering with B vitamins on cognitive aging: meta-analysis of 11 trials with cognitive data on 22,000 individualsAm J Clin Nutr, 2014 · PMID 24965307
Vitamin B supplementation, homocysteine levels, and the risk of cerebrovascular disease: a meta-analysisNeurology, 2013 · PMID 24132976
Homocysteine Lowering with Folic Acid and B Vitamins in Vascular Disease (HOPE-2 Trial)N Engl J Med, 2006 · PMID 16531614
Homocysteine Lowering and Cardiovascular Events after Acute Myocardial Infarction (NORVIT Trial)N Engl J Med, 2006 · PMID 16531613