Does vitamin B12 help with anxiety and depression?

Not in people whose B12 is normal. A meta-analysis of 16 randomized trials in 6,276 people without an overt B12 deficiency found no overall effect of B12 or B-complex supplements on measures of depression. For anxiety, the best pooled answer comes from B-complex trials: in 562 people, the effect on anxiety was a standardized difference of 0.03, which is no effect. We found no randomized trial of vitamin B12 alone with anxiety as its outcome.

Myth. Taking B12 to calm anxiety is not supported by any trial we could find. The pooled B-complex trials found no effect on anxiety, and the main B12 meta-analysis could not even estimate B12 on its own, because there was too little data.

Unsettled. Two questions stay open, and for named reasons. A meta-analysis of multivitamin and mineral supplements in healthy people found a small fall in anxiety, a standardized difference of 0.32, but those pills combine many nutrients and the result cannot be credited to B12. And folate with B12 taken over months may lower the chance of depression returning or starting, a finding that rests on one and two studies.

The results that can be drawn on a risk scale

Randomized trialsObservational data

The top row is an association in observational data and cannot show that B12 caused anything. The two trial rows rest on one and two studies, and both tested folate with B12, so neither is a B12 result alone. No source gives a baseline risk, so none of these can be turned into an absolute number. Sources: cards ev-b12a-07 and ev-b12a-05 below.

What the trials found

B12 for depression in people who are not deficient

The main synthesis is a 2021 meta-analysis of randomized trials in people without advanced neurological disease or overt B12 deficiency, 16 trials and 6,276 people in total. Its authors write that they found no overall effect of vitamin supplementation on measures of depression, and they rated that part of the evidence moderate in quality. The trials in it gave B12 alone or together with other B vitamins. The reviewers wrote that an estimate for B12 alone was not possible due to insufficient data. That gap is itself the finding: B12 on its own has barely been tested for mood.

B vitamins and anxiety

A meta-analysis of randomized trials that gave at least three B vitamins daily for at least four weeks, to healthy and at-risk adults, is the most direct pooled answer on anxiety. In 562 people the standardized difference for anxiety was 0.03, with a 95% confidence interval from minus 0.13 to 0.20 and p = 0.71. The same pool found a small benefit for stress, 0.23 with an interval from 0.02 to 0.45, and a benefit for depressive symptoms of 0.15 in 568 people that did not reach significance. That is a B-complex result. B12 was one ingredient among several.

A systematic review of 20 randomized trials in 2,256 adults with depression, anxiety disorders or their symptoms looked at B vitamins and vitamin D together. Some B-vitamin trials, including ones that used B12 or methylcobalamin, lowered depression scores. For anxiety, the review says results were available only for vitamin D. It pooled nothing, and many of its trials mixed B vitamins with other compounds.

The multivitamin meta-analysis that did find a fall in anxiety pooled placebo-controlled trials of at least 28 days in people from the general population. Anxiety fell by a standardized difference of 0.32, interval 0.16 to 0.48. Perceived stress fell by 0.35. Depression changed by 0.20, which did not reach significance. A standardized difference of 0.32 is small, and it disagrees with the B-complex pool above, which found nothing for anxiety.

Folate and B12 alongside antidepressants

Added to antidepressants in adults with major depression, folate and B12 for days to a few weeks did not improve symptoms, a standardized difference of minus 0.12 with an interval from minus 0.45 to 0.22, across 5 studies. Longer use was linked with lower odds of relapse, an odds ratio of 0.33 from one study, and with a lower risk of clinically significant symptoms in people at risk, a risk ratio of 0.65 from two studies. Those are relative numbers with no baseline given, so we cannot say how many people that is.

Single trials

In 279 adults aged 65 or older with mild cognitive impairment and high homocysteine, 500 micrograms of methylcobalamin with folic acid daily lowered depression scores at 12 months, and the effect was not sustained at 24 months. Depression was a secondary outcome. In 70 men on methadone maintenance, a 12-week multivitamin that contained B12 improved depression but did not have a significant effect on anxiety compared with placebo.

B12 in the diet

Observational studies pooled in a 2022 meta-analysis link the highest dietary B12 intake with a risk ratio for depression of 0.86 against the lowest, an interval from 0.75 to 0.99. That is 14% lower in relative terms, and the source gives no absolute risk. It is an association, and B12 intake tracks the quality of the whole diet.

Who should be careful

Not for everyone. The people for whom B12 and mood may really connect are those who are short of it. NIH ODS says some studies have found associations between B12 deficiency or low intake and depression. It also says gastric acid inhibitors and metformin may affect B12 levels. In a meta-analysis of 4 trials in type 2 diabetes, metformin lowered blood B12 by about 57 pmol/L after 6 weeks to 3 months.

None of these trials supports using B12 in place of treatment for anxiety or depression: added to antidepressants for days to a few weeks, folate and B12 did not improve symptoms. If you take metformin or a stomach acid medicine and your mood has changed, a B12 blood test is the step that makes sense, and it is a question for the person who prescribes your medicine. Taking B12 without a test will not tell you whether low B12 was ever the problem.

B12 has no tolerable upper intake level. The US Food and Nutrition Board did not set one because of its low potential for toxicity, according to NIH ODS. That is a statement about safety, and it says nothing about benefit. We found no card on B12 and pregnancy, children or allergy for this question.

What expert bodies say

NIH ODS, the US federal office for dietary supplements, notes the association between B12 deficiency or low intake and depression in its fact sheet for health professionals. It does not say that B12 supplements treat anxiety or depression. We found no US or European body that recommends B12 for anxiety in people with normal B12 levels.

How we searched

Searched: a local copy of PubMed on 7 October 2026, for vitamin B12, cobalamin, cyanocobalamin or methylcobalamin with anxiety, depression or mood (331 hits, top 40 screened), the same terms with anxiety or stress (272 hits, top 30 screened), B-vitamin meta-analyses on anxiety or stress (21 hits) and methylcobalamin with depression (8 hits). We also searched the NIH ODS fact sheet, the US trial registry, which had nothing on B12 and anxiety, and the web for recent trials and meta-analyses. Five of the included papers were checked against Retraction Watch. None was retracted.

Included: four meta-analyses and one systematic review of randomized trials, one meta-analysis of observational studies, two randomized trials, a meta-analysis on metformin and B12, and three passages from the NIH ODS fact sheet.

Excluded: a genetic association study across many disorders, where the anxiety finding was for B vitamins as a group. A narrative review on stress in women with no numbers in its abstract. Trials whose main outcome was cognition, or that combined methylcobalamin with herbs. Studies of vitamin B6 alone, and a study of perinatal nutrient levels focused on vitamin D.

What we read: the full Results section of the 2021 B12 meta-analysis. Abstracts for the rest.

What we could not get: full texts of the B-complex and multivitamin meta-analyses, which are not in our local copy. And any randomized trial of vitamin B12 alone with anxiety as its main outcome, in PubMed, the trial registry or on the web.

What would change this answer

A randomized trial of B12 alone, with anxiety as its main outcome. We found none, finished or registered.
A trial that enrols people with low or borderline B12, rather than people with normal levels, and measures anxiety and depression after the deficiency is corrected.
Trials in people on metformin or acid-suppressing drugs, who are the most likely to run short.
Larger, longer trials to test the relapse and onset signals for folate with B12, which now rest on one and two studies.

More on this vitamin: the vitamin B12 guide, vitamin B12 and fatigue and vitamin B12 and sleep.

The rest of the nutrient, in one place. Vitamin B12: who actually needs to worry, and why the damage can be permanent → What it does, how much you need, who runs short, and what too much does, with the evidence level shown on every line.

The full guide

Vitamin B12: who actually needs to worry, and why the damage can be permanent

The same question for other foods (anxiety)

Sources

ev-b12a-01 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 6276
We also found no overall effect of vitamin supplementation on measures of depression.
Who: patients without advanced neurological disorders or overt vitamin B12 deficiency
Effect: no overall effect on measures of depression (6 trials reported depressive symptoms)
Certainty: Main synthesis for B12 and mood; depression domain rated moderate quality; anxiety not analyzed.
Nutrients, 2021 · checked 2026-10-07 · we read the abstract
ev-b12a-02 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials, Results · n = —
A meta-analysis estimate for B12 alone and a meta-regression model were not possible due to insufficient data.
Who: patients without advanced neurological disorders or overt vitamin B12 deficiency
Effect: no pooled estimate for B12 alone (insufficient data)
Certainty: The gap itself is the finding: B12 alone is almost untested for mood.
Nutrients, 2021 · checked 2026-10-07 · we read the fulltext
ev-b12a-03 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized controlled trials · n = 562
A benefit to depressive symptoms did not reach significance (n = 568, SMD = 0.15, 95% CI = -0.01, 0.32, p = 0.07), and there was no effect on anxiety (n = 562, SMD = 0.03, 95% CI = -0.13, 0.20, p = 0.71).
Who: healthy and 'at-risk' individuals in RCTs of daily supplementation with at least 3 B group vitamins
Effect: anxiety SMD 0.03 (95% CI -0.13 to 0.20, p=0.71); stress SMD 0.23 (0.02 to 0.45); depressive symptoms SMD 0.15 (-0.01 to 0.32)
Certainty: B complex, not B12 alone; the most direct pooled answer on anxiety.
Nutrients, 2019 · checked 2026-10-07 · we read the abstract
ev-b12a-04 · Meta-analysis or systematic review · meta-analysis of randomized placebo-controlled trials · n = —
Supplementation reduced the levels of perceived stress (standard mean difference [SMD]=0.35; 95% confidence interval [CI]=0.47-0.22; p=.001), mild psychiatric symptoms (SMD=0.30; 95% CI=0.43-0.18; p=.001), and anxiety (SMD=0.32; 95% CI=0.48-0.16; p<.001), but not depression (SMD=0.20; 95% CI=0.42-0.030; p<.089).
Who: nonclinical samples, general population, multivitamin/mineral supplements for at least 28 days
Effect: anxiety SMD 0.32 (95% CI 0.16 to 0.48, p<.001); perceived stress SMD 0.35; depression not significant (SMD 0.20)
Certainty: Combined supplements, so the effect cannot be attributed to B12; diverges from the B-complex meta-analysis on anxiety.
Psychosom Med, 2013 · checked 2026-10-07 · we read the abstract
ev-b12a-05 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized placebo-controlled trials · n = 5 studies
We found that the short-term use of vitamins (days to a few weeks) does not contribute to improve depressive symptoms in adults with major depression treated with antidepressants (5 studies, standardized mean difference = -0.12, 95% confidence interval--95% CI = -0.45, 0.22), but more prolonged consumption (several weeks to years) may decrease the risk of relapse (1 study, odds ratio (OR) = 0.33, 95% CI = 0.12, 0.94) and the onset of clinically significant symptoms in people at risk (2 studies, risk ratio = 0.65, 95% CI = 0.43, 0.98).
Who: adults with major depression treated with antidepressants, and people at risk of depression
Effect: short-term add-on: SMD -0.12 (95% CI -0.45 to 0.22); relapse OR 0.33 (0.12 to 0.94, 1 study); onset RR 0.65 (0.43 to 0.98, 2 studies)
Certainty: Few trials, high heterogeneity; long-term signals rest on 1 to 2 studies.
Int Psychogeriatr, 2015 · checked 2026-10-07 · we read the abstract
ev-b12a-06 · Meta-analysis or systematic review · systematic review of randomized controlled trials, no meta-analysis · n = 2256
As for anxiety symptoms, the availability of results is limited to adjuvant vitamin D therapy.
Who: adults with major depressive disorder, generalized anxiety disorder, or depressive or anxiety symptoms
Effect: B vitamins incl. B12/methylcobalamin lowered depression scores in some trials; no B-vitamin trial results for anxiety
Certainty: Narrative synthesis; many trials combined B vitamins with other compounds.
Nutr Neurosci, 2023 · checked 2026-10-07 · we read the abstract
ev-b12a-07 · Observational data · meta-analysis of observational studies · n = —
The pooled RR (95% CI) of depression for the highest vs the lowest category of dietary vitamin B1, B2, B6, and B12 was 0.69 (0.55-0.87), 0.77 (0.67-0.89), 0.81 (0.71-0.93), and 0.86 (0.75-0.99), respectively.
Who: adults in observational studies of dietary B vitamins and depression
Effect: highest vs lowest dietary B12: RR 0.86 (0.75 to 0.99)
Certainty: Observational; B12 intake tracks overall diet quality.
Nutr Rev, 2022 · checked 2026-10-07 · we read the abstract
ev-b12a-08 · Randomized controlled trial(s) · randomized placebo-controlled trial, methylcobalamin 500 ug + folic acid 400 ug daily, 24 months · n = 279
The supplement led to a significant reduction in depressive symptoms at month 12, though this effect was not sustained.
Who: MCI outpatients aged 65 years or older with serum homocysteine >=10.0 umol/L
Effect: HDRS lower at month 12 (P=0.012); no significant group difference at month 24
Certainty: Secondary outcome; effect not sustained; combined with folic acid.
Clin Nutr, 2020 · checked 2026-10-07 · we read the abstract
ev-b12a-09 · Randomized controlled trial(s) · double-blind randomized placebo-controlled trial, 12 weeks · n = 70
Multivitamin supplementation improved depression but did not have a significant impact on anxiety in patients undergoing MMT.
Who: male MMT patients over the age of 18
Effect: no significant between-group difference in anxiety; significant difference in depression favoring multivitamin
Certainty: Small, specific population; multivitamin with B1, B2, B3, B5, B6, B12, C, E, biotin, folic acid, zinc.
Int J Psychiatry Med, 2023 · checked 2026-10-07 · we read the abstract
ev-b12a-10 · Position of an expert body · agency fact sheet · n = —
In addition, some studies have found associations between vitamin B12 deficiency or low vitamin B12 intakes and depression [37-39].
Who: people with vitamin B12 deficiency or low intake
Effect: association only; no treatment effect stated
Certainty: Explains why testing B12 status matters before expecting a mood benefit.
NIH Office of Dietary Supplements, Vitamin B12 fact sheet for health professionals · checked 2026-10-07 · we read the section
ev-b12a-11 · Position of an expert body · agency fact sheet · n = —
The FNB did not establish a UL for vitamin B12 because of its low potential for toxicity [1].
Who: general population
Effect: no UL set by the Food and Nutrition Board
Certainty: Safety of high doses does not imply benefit.
NIH Office of Dietary Supplements, Vitamin B12 fact sheet for health professionals · checked 2026-10-07 · we read the section
ev-b12a-12 · Position of an expert body · agency fact sheet · n = —
Vitamin B12 supplements may interact with medications, and some medications, including gastric acid inhibitors and metformin, may affect vitamin B12 levels.
Who: individuals taking gastric acid inhibitors or metformin on a regular basis
Effect: reduced B12 absorption and serum levels
Certainty: People on these drugs with low mood may have true deficiency worth testing.
NIH Office of Dietary Supplements, Vitamin B12 fact sheet for health professionals · checked 2026-10-07 · we read the section
ev-b12a-13 · Meta-analysis or systematic review · systematic review of 26 papers with meta-analysis of 4 trials · n = 4 trials
Meta-analysis performed on four trials demonstrated a statistically significant overall mean B12 reducing effect of metformin of 57pmol/L [WMD (fixed)=-0.57 (95% CI: -35 to -79pmol/L)] after 6weeks to 3months of use.
Who: patients with type 2 diabetes taking metformin
Effect: mean B12 reduction 57 pmol/L (95% CI 35 to 79) after 6 weeks to 3 months
Certainty: Pooled estimate from 4 trials.
Diabetes Metab, 2016 · checked 2026-10-07 · we read the abstract

How this page was made. Evidence was extracted from primary sources into cards, every number was re-checked against the source, and the text was written from those cards. Bioma Learn has no human medical reviewer at this time, and we say so rather than invent one. Methodology. This is information, not medical advice.