Struggling with the black dog of depression? The supplement aisle abounds with options for people seeking a non-medicinal remedy — but figuring out what works and what doesn't can be a challenge for consumers and experts alike.
That's because the data are generally poor, says Dr. Charles Raison, associate professor of psychiatry in the College of Medicine at the University of Arizona in Tucson.
There are some exceptions. Hundreds of studies have investigated the effects of omega-3 fatty acids and St. John's wort. Researchers have been studying a compound known as SAM-e for decades. And, more recently, evidence on the effectiveness of folate compounds has been piling up.
Even though all of these compounds are available over the counter in one form or another, there are precautions you should take if you choose to self-medicate, to avoid potential drug interactions and make sure you're getting adequate mental health care.
"We always recommend that patients take these natural supplements under the care of a doctor and not independently," says Dr. George Papakostas, an associate professor of psychiatry at Harvard Medical School.
Here's a look at what the latest studies have shown.
Omega-3 fatty acids
Omega-3s already have a solid reputation as heart-healthy supplements. Researchers are now trying to figure whether the fatty acids, particularly the ones found in seaweed and oily fish such as salmon, might have a role in treating depression.
For more than a decade, studies have pointed to an association between fish consumption and depression: Across the globe, rates of depression are lower in populations that eat more fish, particularly omega-3 rich fish such as salmon, tuna, sardines and mackerel. Studies have also shown that omega-3 levels are lower in people with depression than in people without.
These findings, in turn, have prompted hundreds of studies to determine whether omega-3 supplements can help treat depression. Two recent reviews analyzed the data from dozens of the most well-designed of these studies, and they came to a similar conclusion: Omega-3s appear most likely to help people with severe depression but are unlikely to help those with minor depression or who are simply in a bad mood.
One of the reviews, published in the journal of the American College of Nutrition in 2009, found that there may be important differences depending on the type of omega-3 supplement. Fish oil contains two types: DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). Studies that used pure DHA or more than 50% DHA reported no effect on depression. Studies using pure EPA or more than 50% EPA found that symptoms improved.
But the authors of both reviews agreed that drawing conclusions from the existing body of evidence was a challenge. Even the most well-designed studies were small and brief. Many included patients with a wide range of symptoms and different types and severity of depression. And few used the same treatment regimens: Some gave participants omega-3s alone, some gave omega-3s along with other drugs, and doses varied widely.
Though the usefulness of omega-3s in depression is still fuzzy, one thing is clear: Studies haven't turned up evidence of harmful side effects, just "fishy, burpy breath," says Mary Fristad, professor of psychiatry, psychology and human nutrition at Ohio State University Medical Center in Columbus.
Because they're so safe, researchers are now beginning to study whether omega-3s might help treat depression in children. A couple of recent, small studies — one in Israel, one in Australia — showed a 40% to 50% improvement of depressive symptoms in children given omega-3s. (This is a new area of investigation, and the findings are very preliminary, stresses Fristad, who is doing research in this area.)
Other scientists are looking at whether omega-3s might help conditions related to depression, such as anxiety. In a study published earlier this year, medical students who took a daily omega-3 supplement containing 2,085 milligrams of EPA and 348 mg DHA for 12 weeks had a 20% reduction in anxiety compared with students who took a placebo.
Despite such findings, "it's too soon to say omega-3s can combat stress," says study lead author Janice Kiecolt-Glaser, professor of psychiatry and psychology at Ohio State University College of Medicine. But in terms of general health, it's a good idea to make sure you're getting enough of them in your diet, she says.
Folate, a B vitamin found in leafy greens, beans and eggs, is a nutrient that's essential for good health. Though its effects on depression haven't been studied as extensively as omega-3s, existing studies have shown consistently positive results, says Dr. David Mischoulon, an associate professor of psychiatry at Harvard Medical School, who has researched the vitamin.
As with omega-3s, the first clue that folate might help treat depression came from population studies showing an association between folate deficiencies and depression. Scientists began to ask whether administering the vitamin to patients would help treat the condition.
Studies have focused on three forms of the vitamin: folic acid, the synthetic version used in supplements and fortified foods; 5-methylene tetrahydrofolate, also known as 5-MTHF, methylfolate or L-methylfolate, which is a breakdown product of folic acid and folate; and folinic acid, a synthetic compound that gets broken down into 5-MTHF.