Updated

Neuroscientists have suspected for a long time that people who suffer with major depression might be unable to properly metabolize the B vitamin folic acid (folate) to a form that can pass through the blood-brain barrier--a kind of "filter" of membranes that isolates the brain and nervous system from the rest of the body.

The active metabolite--L-methyl folate--is known to be important in modulating levels of brain chemical messengers like serotonin and norepinephrine. And those are the chemical messengers suspected to be deficient in people with mood disorders.

Now, a recent research study has shown that taking L-methyl folate by mouth, in addition to an antidepressant, significantly increases the odds that the antidepressant will work. This is extremely important data, because up to 70 percent of those with major depression don't respond sufficiently well to just one medication. The fact that a vitamin improves those statistics is big news.

L-methyl folate is classified as a "medical food" and marketed under the trade name Deplin. It is available only by prescription. The dosage used in the study was 15 mg a day. Half that much didn't seem to work.

L-methyl folate exerted its beneficial effects within 30 days.

Since L-methyl folate has no known side effects, it seems reasonable to suggest that most people who are taking the kind of antidepressant that was the focus of the study should try it. Those antidepressants are the ones known as SSRIs, or serotonin reuptake inhibitors. They work by interfering with the "cellular undertow" that absorbs serotonin back into brain cells that have released it. That means the serotonin stays around longer in the synapses between brain cells and can exert its effects for longer. Apparently, L-methyl folate contributes to this process.

Taking L-methyl folate is by no means the only strategy patients suffering with major depression should consider. I have found that patients also improve more reliably and substantially when they use bright light therapy along with antidepressants. And the recent availability of magnetic stimulation of areas of the brain implicated in depression (rTMS) is also a very powerful option.

We psychiatrists are now armed with synergistic tools to fight major depression. They include psychotherapy, medication, magnetic stimulation, L-methyl folate and bright light therapy. While there are others still, the ones I mention are not known to have any significant side effects.

Therefore, using them in combination (while being alert for any signs of the "high" phase of bipolar disorder known as mania) make good sense.

If you or someone you care about is taking a serotonin reuptake inhibitor to combat depression, but with lackluster results, taking L-methyl folate (Deplin) is now known to be a hopeful next step. But even if the results remain less than optimal, the other treatment modalities I have noted should be deployed.

Fighting depression is all about being resolute to judiciously, yet determinedly, deploy the very good weapons now at our disposal.

Dr. Keith Ablow is a psychiatrist and member of the Fox News Medical A-Team. Dr. Ablow can be reached at info@keithablow.com. His team of Life Coaches can be reached at lifecoach@keithablow.com.