A recent meta-analysis, published in the Journal of Epidemiology and Community Health, analyzed 11 studies (with 15,315 participants) and found a significantly increased risk of depression in individuals with low folate levels. A 42-percent greater risk of depression was noted in those with lower folate levels. Other studies have shown an elevated incidence of folate deficiency in people with depression; it is possible one-third of depressed patients may be folate deficient. Folate, as 5-methyltetrahydrofolate (5MTHF) is a methyl donor molecule that recycles homocysteine to methionine, which becomes S-adenosylmethionine (SAMe). In turn, SAMe is involved in methylation reactions that are involved in many areas of human metabolism, including the serotonin and catecholamine (dopamine, norepinephrine, epinephrine) pathways. 5MTHF may itself be involved in neurotransmitter production, as a cofactor to tetrahydrobiopterin (BH4). Folate supplementation may have a beneficial effect on mood, as well as improving the response of depressed patients to SSRI antidepressants.
Gilbody S, Lightfoot T, Sheldon T. Is low folate a risk factor for depression? A meta-analysis and exploration of heterogeneity. J Epidemiol Community Health 2007;61:631-637.
