A method for increasing serotonin levels in a person includes identifying a person having a deficient serotonin level and administering to the person a composition incorporating hydroxycitric acid, preferably in the form of an extract of Garcinia cambogia, in an amount sufficient to increase the person's serotonin levels. The method also can incorporate administering chromium, preferably in the form of oxygen-coordinated, niacin-bound chromium, and gymnemic acid, preferably in the form of an extract of Gymnema sylvestre, to synergistically work to further increase serotonin levels in the person.