A vitamin is a nutrient that an organism such as human needs, but the organism is not in itself sufficiently to make. Initially it was thought that all vitamins had an amine structure, something not proved to be wrong. The name, coined by Casimir Funk, is a compilation of vital and amine. In the naming of vitamins is initially based on a simple 1-letter names, such as vitamin A. After wards the vitamins are classified by functional effect. Vitamins are necessary for the functioning of enzymes are the class of co-enzymes. The Dutch Health Council makes recommendations how someone vitamins required daily. For each vitamin there is a Recommended Daily Allowance (RDA).