The cool, clean smell of peppermint is distilled from the leaves and top of the herb. It has been popular ever since the ancient Egyptians used it as a soothing digestive aid. Peppermint is used in commercial medicine for treatment of irritable bowel syndrome. It stimulates the intestines, causing gas to be expelled, and then relaxes the muscles to a more normal state. It is also useful to treat nausea and colic.