"A lot of people use meditation, but it's not a practice considered part of mainstream medical therapy for anything," said Madhav Goyal, an assistant professor in the Division of General Internal Medicine at the Johns Hopkins University School of Medicine.
"But in our study, meditation appeared to provide as much relief from some anxiety and depression symptoms as what other studies have found from antidepressants," Goyal said.
These patients did not typically have full-blown anxiety or depression, researchers said.
Scientists evaluated the degree to which those symptoms changed in people who had a variety of medical conditions, such as insomnia or fibromyalgia, although only a minority had been diagnosed with a mental illness.
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The findings held even as the researchers controlled for the possibility of the placebo effect, in which subjects in a study feel better even if they receive no active treatment because they perceive they are getting help for what ails them.
To conduct their review, the investigators focused on 47 clinical trials performed through June 2013 among 3,515 participants that involved meditation and various mental and physical health issues, including depression, anxiety, stress, insomnia, substance use, diabetes, heart disease, cancer and chronic pain.
They discovered low evidence of improvement in stress and quality of life. There was not enough information to determine whether other areas could be improved by meditation. In the studies that followed participants for six months, the improvements typically continued.
Researchers also found no harm came from meditation.
Mindfulness meditation, the type that showed the most promise, is typically practiced for 30 to 40 minutes a day. It emphasises acceptance of feelings and thoughts without judgement and relaxation of body and mind, researchers said.
The study was published in JAMA Internal Medicine.