Peppermint has greenish-purple lance-shaped leaves while the rounder leaves of spearmint are more of a grayish green color. The taste of both peppermint and spearmint bear a flavor that can be described as a cross between pepper and chlorophyll, with peppermint being a bit stronger and spearmint being a little more cool and subtle.
Mint leaves are very low in calories -- a 1/4-cup serving of fresh peppermint contains only 4 calories, while an equivalent serving of spearmint provides just 10. Fresh mint leaves contain negligible amounts of protein and fat, and provide small amounts of carbohydrates. A serving of peppermint offers 1 gram of total carbohydrates -- including 0.5 grams of fiber -- while spearmint contains 2 grams of carbohydrates per serving, including 1.6 grams of fiber. The fiber in mint leaves offers health benefits, including helping to reduce cholesterol levels and lowering your risk of obesity, according to whfoods.com.
Spearmint is pleasantly aromatic herb packed with numerous health benefiting vitamins, antioxidants and phyto-nutrients.
The leaves and herb parts contain essential oil, menthol. Unlike in peppermint, spearmint leaves composes only small amounts of menthol, 0.5% compared to the 40% in peppermint. Less menthol content would make this herb least pungent and subtly fragrant herb in the mint family, according to whfoods.com.
The herb has low calories (about 43 calories per 100 g) and contains zero cholesterol.
The chief essential oil in spearmint is menthol. Other important chemical components of spearmint are α-pinene, β-pinene, carvone, cineole, linalool, limonene, myrcene and caryophyllene. These compounds in mint help relieve fatigue and stress.
The herb parts are also very good in minerals like potassium, calcium, manganese, iron (148% of RDA), and magnesium. Iron is required for enzymes in cellular metabolism and synthesis of hemoglobin. Potassium is an important component of cell and body fluids that helps control heart rate and blood pressure. Manganese is used by the body as a co-factor for the antioxidant enzyme superoxide dismutase.
Further, the herb is also rich in many antioxidant vitamins, including vitamin A (provides 4054 IU or 135% of RDA), beta-carotene, vitamin C, folates (26% of RDA), vitamin B-6 (pyridoxine), riboflavin and thiamin.