Traditional treatments for depression, specifically antidepressant medications and psychotherapy, have a strong scientific track record of effectiveness. However, they are not perfect by any means, and antidepressants often cause unpleasant side effects. For that reason, many people turn to complementary and alternative treatments, either in place of or in addition to conventional treatment. What does science have to say about their effectiveness?

Dr. David Mischoulon, director of the Depression Clinical and Research Program at Massachusetts General Hospital, says that most common alternative therapies, such as St. John’s wort, omega-3 fish oil and S adenosylmethonine, or SAMe, are relatively well-studied, with 30 to 40 published clinical trials and larger meta-analyses and systematic reviews for each one.

“Results overall favor them over placebo as antidepressants,” he says. “While it is thought that many people’s response to natural remedies is a placebo response, evidence suggests that placebo response rates are equally common with natural products as with standard antidepressants.”

That sounds pretty good. But the experts at National Institutes of Health are, in general, less impressed. Let’s take a closer look.

[See: 8 Ways Meditation Can Improve Your Life.]

St. John’s wort. The National Center for Complementary and Integrative Health reports that studies are mixed; some find benefits similar to antidepressants in a limited number of patients, while others don’t. St. John’s wort likely affects hormone production, specifically reducing cortisol, the so-called “stress hormone,” Mischoulon says. It also acts somewhat like a selective serotonin reuptake inhibitor, or SSRI — a common class of antidepressant — but that effect is “minimal,” he says.

On the negative side, St. John’s wort can interfere with many other medications, including allergy meds, immunodepressants, birth control pills and blood thinners, and inhibit their effectiveness. The risks associated with St. John’s wort may outweigh the benefits, the NCCIH says.

Omega-3 fatty acids. Omega-3s, found in fatty fish and in supplements, are thought to combat inflammation and improve the brain’s messenger systems, Mischoulon says.

Research suggests that omega-3s may provide “small improvement” when used along with conventional antidepressants, but “a lot of questions remain about how, or if, omega-3 supplements work in the body to produce such an effect,” the NCCIH says.

[See: 13 Best Fish: High in Omega-3s — and Environment-Friendly.]

SAMe. “SAMe is a key factor in the synthesis of various key neurotransmitters such as serotonin, norepinephrine, dopamine and acetylcholine,” Mischoulon says. But the evidence that oral SAMe is helpful for depression is not conclusive. The NCCIH says that at least 40 human studies have looked at SAMe for depression, and many found evidence of beneficial effects. But most of the trials were short-lived, included a small number of subjects and had other scientific shortcomings. As a result, the NCCIH does not endorse its use.

Other Alternatives

People often turn to other alternatives, as well.

Yoga, sunlight, vitamin D supplements and meditation all have some evidence to support them, but less than those discussed above, Mischoulon says. “They deserve more research, since early studies are very promising.” Light therapy for seasonal depression, for instance, has had “very encouraging findings,” he says.

The NCCIH concurs, reporting that some studies on mind-body practices such as yoga, meditation and other relaxation or stress-reduction techniques have shown beneficial results when used with standard treatments. “Studies indicate that relaxation training is better than no treatment in reducing symptoms of depression, but is not as beneficial as psychological therapies such as cognitive-behavioral therapy,” the NCCIH explains. Music therapy, though, has not been shown to improve mood in any significant way.

The Clear Winner: Exercise

The only proven alternative therapy for depression is exercise. Numerous studies have shown that regular physical activity is a powerful medicine, both for the prevention and treatment of mild to moderate depression.

“All the research shows that it is in a way superior to just about any form of therapy other than medications, where it is equal,” says New Jersey-based Dr. Ronald L. Kamm, who specializes in sport psychiatry. Exercise releases mood-elevating endorphins, increases neurotransmitter production, provides a sedative-like warming of the body and more. “Exercise remodels the brain,” he says. “Being active creates new neurons. Inactivity is not good for the brain. The neurons react to being a couch potato differently than if you exercise.”

[See: The Many Ways Exercise Fights Depression.]

Playing a sport is even better than solitary exercise, he argues, because social interaction is also helpful in combating depression. Sports relieve pent-up stress, too. “Freud postulated that depression is anger turned inward, so if you can play a sport that involves whacking something, that’s the best,” he says. “Whack a tennis ball or a golf bowl. Bowl and see the pins fly.”

Ask a Doctor Before Trying Alternative Therapies

Despite the inconclusive evidence for most alternative therapies, Mischoulon says he generally recommends them to people with mild depression who are reluctant to try standard drugs or are philosophically inclined toward natural therapies. “I caution people that these treatments are not as well-understood, however, so we don’t know as much about their safety or efficacy. At the other end of the spectrum, some people who have tried everything without benefit or who had a lot of side effects may have nothing to lose by trying these natural products, but these patients are the hardest to treat, so caution is needed. I would not give these therapies to someone who was acutely suicidal, for example.”

Above all, he cautions, no one should try to self-medicate for any psychiatric condition. “They should get an evaluation from a licensed clinician to establish a clear diagnosis, and all medication-based treatments should be undertaken under physician supervision.”

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Do Alternative Therapies Work for Depression? originally appeared on usnews.com