Wikipedia Article About Guero on Wikipedia Red chiles are very rich in vitamin C, and rich in provitamin A. Yellow and especially green chiles (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.