Red chilis contain high amounts of vitamin C and provitamin A. Because of the high amount of vitamin C， some South American athletes consume chili peppers before strenuous exercises. Yellow and especially green chilis (which are essentially unripe fruit) contain a considerably lower amount of both substances. In addition, peppers are a good source of most B vitamins, and vitamin B6 in particular. They are very high in potassium and high in magnesium and iron. Their high vitamin C content can also substantially increase the uptake of non-heme iron from other ingredients in a meal, such as beans and grains.