B vitamins
B vitamins are important in the regulation of neurotransmitters [27] like serotonin, dopamine, and gamma-aminobutyric acid (GABA).
Deficiencies in folates and vitamin B12 are associated with an increased risk of depression. Treating these deficiencies with supplements can help improve depression symptoms [28] in certain groups. Studies [29] have found [30] that folate supplements may improve symptoms of treatment-resistant depression in people with a genetic mutation that affects their folate metabolism.
Studies have also found that vitamin B12 used with antidepressants may delay the onset [31] of depression and improve symptoms [32] in people with depression.