Jalapeño peppers can spice up almost any dish. This variety of hot pepper is generally harvested and sold when it is a glossy dark green, but it turns red as it matures. Jalapeños are just one of many types of chili peppers that are often used as an accent or garnish to add heat to a dish. Although they are usually eaten in quantities too small to provide a significant amount of nutrition, these peppers are a good source of vitamins A and C.