High-dose vitamin B6 tablets have been shown to reduce feelings of depression and anxiety, according to new research.
Young adults studied by the University of Reading reported less of these feelings after a month of taking the supplements.
Past studies have suggested multivitamins can cut stress levels but few have looked into exactly which vitamins may be responsible.
Vitamin B6 is known to boost the body's production of GABA (Gamma-Aminobutyric Acid), a chemical that blocks impulses between the brain's nerve cells.
Lead author Dr David Field said the vitamin "helps the body produce a specific chemical messenger that inhibits impulses in the brain, and our study links this calming effect with reduced anxiety among the participants".
Some 478 people took part and were randomly given either a placebo, or vitamin B6 or B12 at doses higher than the normal recommendation.
B12 showed little difference to the placebo, but B6 had a notable effect on the participants and raised their GABA levels, the study found.
Tuna, chickpeas and many fruits and vegetables contain the vitamin, but Dr Field said supplementation would likely be necessary to achieve a positive effect on a person's mood.
He said the research was at an early stage - and the effects were "quite small" compared with medication - but that B6 could be combined with more traditional therapies.
"One potential option would be to combine Vitamin B6 supplements with talking therapies such as Cognitive Behavioural Therapy to boost their effect," he said.
He added that another benefit is that "nutrition-based interventions produce far fewer unpleasant side effects than drugs".
The research is published in the journal Human Psychopharmacology: Clinical and Experimental.
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