Vitamins B6, B9 (Folate), B12

Our rating
Folate (B9) to boost the effect of anti-depressant medication 1 smiley:  This treatment is promising and may be useful. It has some evidence to support it, but more evidence is needed to be sure it works.
Vitamin B6, Folate (B9) and B12 as a stand-alone treatment Question mark:  This treatment has not been properly researched. It is not possible to say whether it is useful or not.


The rating system

  • 3 smiliesThese treatments are very useful. They are strongly supported as effective by scientific evidence.
  • 2 smiliesThese treatments are useful. They are supported by scientific evidence as effective, but the evidence is not as strong.
  • 1 smileyThese treatments are promising and may be useful. They have some evidence to support them, but more evidence is needed to be sure they work.
  • No smiley On the available evidence, these treatments do not seem to be effective.
  • Question markThese treatments have not been properly researched. It is not possible to say whether they are useful or not.
  • Exclamation MarkSafety or other concerns have been raised for the use of these treatments.

What is it?

Vitamins support normal growth, development, and cell functions. All B vitamins help convert carbohydrates into a source of energy (glucose), and assist in the formation of red blood cells.

How does it work?

It is thought that B vitamins may affect depression in these ways:

  • Some people with depression have been found to have low levels of folate (B9).
  • Vitamin B6, folate (B9) and B12 can change levels of brain chemicals that affect mood (such as serotonin and norepinephrine).
  • SAMe is a natural chemical in the body that may help depression. Folate (B9) and vitamin B12 are involved in the production of SAMe.
  • Vitamin B12 helps maintain the insulation around brain cells. The insulation helps brain cells to communicate.

Is it effective?

Short-term use of vitamins by themselves do not seem to help reduce depression symptoms. A review of studies which looked at the use of combined B vitamins in adults without a depression diagnosis found that there was no benefit of B vitamins compared to a placebo. A further small study found that B vitamins did not improve depression symptoms compared to a placebo in non-depressed adults with either optimal or sub-optimal diets.

Some studies have found that taking folate (B9) alongside anti-depressant medication can result in greater reduction in depression symptoms compared to taking antidepressant medication on its own.

There is very little scientific evidence on vitamin B6 and B12 for the treatment of depression.

More studies of higher quality are needed to better understand the effects of B vitamins on depression.

Are there any disadvantages?

Some vitamin supplements can be harmful or ineffective if you take the wrong dose. For example, large doses of Vitamin B6 can cause nerve damage. Talk to your health care professional if you are thinking of taking supplements.

One study reported mania symptoms in a participant who was taking folate (B9) (and antidepressants). No other studies of B vitamins and depression have reported side effects. However, it is not clear whether the studies have investigated negative effects. More research is needed on the possible side effects of B vitamins.

Where do you get it?

Vitamins are present naturally in food. You can buy vitamin supplements in health food shops, supermarkets or from chemists. They usually come in tablet, capsule or powder form. Vitamins may also be given as an injection by a doctor.


Vitamins as a standalone treatment do not appear to be effective at treating depression. Folate (B9) may help boost the effects of anti-depressants.

Key references

  • Almeida OP, Ford AH & Flicker L. Systematic review and meta-analysis of randomized placebo-controlled trials of folate and vitamin B12 for depression. 2015; 27(5), 727-737.
  • Firth J, Teasdale SB, Allott K, Siskind D, Marx W, Cotter J, et al. The efficacy and safety of nutrient supplements in the treatment of mental disorders: A meta-review of meta-analyses of randomized controlled trials. World Psychiatry: Official Journal of the World Psychiatric Association (WPA). 2019;18(3):308-24.
  • Young LM, Gauci S, Arnoldy L, Martin L, Perry N, White DJ, et al. Investigating the Effects of a Multinutrient Supplement on Cognition, Mood and Biochemical Markers in Middle-Aged Adults with ‘Optimal’ and ‘Sub-Optimal’ Diets: A Randomized Double Blind Placebo Controlled Trial. Nutrients. 2022;14(23):5079.
  • Young LM, Pipingas A, White DJ, Gauci S, Scholey A. A Systematic Review and Meta-Analysis of B Vitamin Supplementation on Depressive Symptoms, Anxiety, and Stress: Effects on Healthy and ‘At-Risk’ Individuals. Nutrients. 2019;11(9):2232.

Last reviewed and updated: 7 August 2023