"Mindfulness meditation" - a Buddhist technique aimed at focusing on the present moment - also showed promise in alleviating stress and enhancing quality of life, scientists found.
Researchers analysed data from 47 clinical trials involving 3,500 participants looking at the effects of meditation on a multitude of problems, including depression, anxiety, stress, insomnia, diabetes, heart disease, chronic pain and cancer.
They found "moderate" evidence that eight weeks of meditation training improved symptoms of anxiety, depression and pain.
Low evidence of reduced stress and better quality of life was also seen, while there was insufficient evidence for other benefits.
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Lead researcher Dr Madhav Goyal, from Johns Hopkins University School of Medicine in Baltimore, US, said: "In our study, meditation appeared to provide as much relief from some anxiety and depression symptoms as what other studies have found from antidepressants."
He added: "A lot of people have this idea that meditation means sitting down and doing nothing, but that's not true. Meditation is an active training of the mind to increase awareness, and different meditation programmes approach this in different ways."
Mindfulness meditation is typically practiced for 30 to 40 minutes a day. It emphasises relaxation of the body and mind, and the acceptance of feeling and thoughts without judgment.
The evidence indicated that the benefits of meditation were not simply due to a "placebo effect", said Dr Goyal.
Follow-up studies showed that the improvements typically continued for at least six months.
However, participants did not generally have full-blown anxiety or depression. Further research is needed to clarify the benefits of meditation and see if they increase with greater amounts of practice, said Dr Goyal.
The research appears in the latest online issue of the journal JAMA Internal Medicine.