A small study suggests adding SAM-e to a patient's antidepressant treatment helps more people improve their symptoms.
The supplement also had fewer side effects than medications that are approved by the FDA for people who don't respond to antidepressants.
Previous studies have shown SAM-e can influence brain chemicals and might work as a mood booster on its own.
The way it works is not clear.
Details on the new research can be found in the "American Journal of Psychiatry."
