Barley grass supplements are promoted for multiple uses. Claims have been made that they help prevent and fight cancer, lower cholesterol, detoxify many pollutants, protect against solar and other forms of radiation, boost energy and immunity, enhance wound healing, help with digestion, fight tooth decay and bad breath, promote healthy skin, reverse graying of hair and lower blood pressure, among other things. There is no credible evidence to support any of these claims at this time.