As such, taking something just to feel well by artificial means usually carries a downside - sometimes negligible, sometimes substantial, often unknown. If you are healthy, have excellent health habits, eat a well balanced diet modest in calories, and maintain an ideal weight, taking supplements is unlikely to give you major extra benefit. If you are overweight, smoke, and have generally poor dietary and health habits, supplements are unlikely to help you either. However, for the average person with fair health habits, there is evidence that certain supplements such as antioxidant vitamins may be of benefit. For the post-menopausal woman, calcium supplementation is probably of benefit.
Herbal supplements are as of yet unproven.
Medical textbooks are still awaiting more conclusive evidence before making specific recommendations. Consult your physician for recommendations which pertain to you. Some of the danger of medicines, drugs and supplements is not from the chemicals in these products. In fact, much of the hazard comes through the hands of the user. The characteristics of each of these groups should be obvious.