Low levels of folate, also known as folic acid or vitamin B9, have been associated with depressive symptoms in the general population. A 2014 article by A.L. Sharpley et al. in the Journal of Affective Disorders explored whether folate has protective effects. Teens and young adults (ages 14–24) at high risk for mood disorders due to a family history of these illnesses were randomly assigned to receive either folate supplements (2.5 mg daily) or placebo for up to three months. While there were no significant differences in the percentage of young people in each group who went on to be diagnosed with a mood disorder, in the folate group there was a delayed onset of illness in those who went on to become unwell.
Researchers are exploring the therapeutic potential of nutraceuticals, or nutritional treatments. Folate, also known as folic acid or vitamin B9, is one of the most important nutritional elements for mental health.
The folate found in foods such as dark leafy greens must be broken down further in order to be used in the body. Folate first breaks down into dihydrofolate (DHF), which is turned into tetrahydrofolate (THF). At the 2014 meeting of the International Society for Bipolar Disorders, researcher J.H. Baek described a pathway by which THF is turned into a form called 5,10 MTHF, which is turned into a form called 5 MTHF. 5 MTHF is important for the function of the enzyme tryptophan hydroxylase and for clearing homocysteine, an amino acid that is cardio- and neuro-toxic.
L-methylfolate, the active ingredient in the medication Deplin, is an already-broken-down form of folate that the brain can use more readily than the folate from food. L-methylfolate is converted directly to 5 MTHF, so it is effective in 15% to 35% of the normal population who have a deficiency in the enzyme MTHF reductase, which converts THF to 5 MTHF. One genetic variant (a C to T allele variation 677) that results in one type of deficiency in MTHF reductase has a 42% incidence among Asians, 34% among Caucasians, and 8% among Africans, and these individuals would benefit from l-methylfolate.
Folate and Medications for Bipolar Disorder
Certain medications lead to deficits in folate, so patients should consider taking a nutritional supplement.
The anticonvulsant drug lamotrigine inhibits the conversion of folate to DHF and DHF to THF, so folate supplementation is a good idea for those patients taking lamotrigine.
The mood stabilizer valproate inhibits the conversion of toxic homocysteine to methionine and then to s-adenosyl methionine (SAMe), which acts like an internally-produced antidepressant. Thus valproate increases homocysteine, and patients on valproate should be routinely treated with folate and vitamin B12 to help lower homocysteine levels in the blood.
Folate supplements are recommended for depressed patients who are having an inadequate response to antidepressants, since the nutrient helps antidepressants work better even when patients do not have a folate deficiency. Researcher Andrew Stoll recommends folate (1mg for women and 2mg for men). However, those patients who have one of the genetic conditions that leads to a deficiency in MTHF reductase should take l-methylfolate instead of regular folate. Researcher Mauricio Fava and colleagues showed that l-methylfolate at doses of 15mg (but not 7.5mg) was more effective than placebo in patients with unipolar depression.
While the nutritional supplement folate (also known as folic acid or vitamin B9) can be useful for depression, there appears to be one instance when augmentation with regular folate could be counterproductive. In those with a transport defect associated with a MTHR (methyl tetrahydrofolate reductase) deficiency, folate can compete with l-methylfolate for uptake into the brain. Folate would thus limit the beneficial effects of l-methylfolate supplementation, which is required for this 15% of the population.
A study of 85,000 children in Norway that was recently published in the Journal of the American Medical Association showed that women who took folic acid during pregnancy were 40% less likely to have a child who developed autism.
A summary of the research by National Public Radio explained:
Folic acid is the synthetic version of a B vitamin called folate. It’s found naturally in foods such as spinach, black-eyed peas and rice. Public health officials recommend that women who may become pregnant take at least 400 micrograms of folic acid every day to reduce the chance of having a child with spina bifida.
The folic acid’s effect reduced the most severe cases of autism but did not seem to have an effect on the incidence of more mild forms, such as Asperger syndrome. The benefits were seen in those women who had been taking folic acid for 4 weeks before conception and continued to take the supplement during the first 8 weeks of pregnancy.
The B vitamin folate has been shown to be a useful augmentation treatment for patients who are nonresponsive or only partially responsive to selective serotonin reuptake inhibitor (SSRI) antidepressants. Treatment with folate works even in those who are not folate-deficient at baseline.
When folate is broken down in the body by reductase enzymes, it turns into the active form L-methylfolate, and crosses the blood-brain barrier. Maurizio Fava and colleagues at Massachusetts General Hospital (MGH) performed two placebo-controlled, randomized studies of L-methylfolate for depression. There was significantly greater improvement when SSRIs were augmented with L-methylfolate than when they were augmented with placebo. The results were significant with the use of 15mg of L-methylfolate, but not with 7.5mg, suggesting dose-related effects. Read more