Mints exert a wide range of health benefits. Like other aromatic plants, their primary application has been as a carminative and digestant. The oil of the peppermint plant is an excellent example. It has been shown to relieve spasms of the gastrointestinal tract and gas. In fact, an enteric- coated peppermint oil capsule has been shown to be very effective in relieving symptoms of irritable bowel syndrome. (Enteric coating prevents the oil from being released in the stomach.) Peppermint oil relaxes smooth muscle. Once the smooth muscles surrounding the intestine are relaxed, there is less chance of spasm and the indigestion that can accompany it. The menthol contained in peppermint may be a key reason for this bowel-comforting effect.
Peppermint contains a compound known as perillyl alcohol that has been shown to inhibit the growth or formation of cancer. It also contains the substance rosmarinic acid, a powerful antioxidant that blocks the production of allergy-producing leukotrienes. The high content of rosmarinic acid may be the reason extracts of peppermint have been shown to help relieve the nasal symptoms of allergic rhinitis (hay fever).
Source: Encyclopedia of Healing Foods