Vitamins, defined as essential micronutrients required in trace quantities that cannot be synthesized by mammals, are essential for the metabolism of all living organisms and are synthesized by plants or microorganisms. In addition to their in vivo nutritional-physiological roles as growth factors for men, animals, plants and microorganisms, vitamins are now increasingly being introduced as food/feed additives, as health aids, as medical-therapeutic agents, and also as technical aids. Today, many processed feeds, foods, pharmaceuticals, chemicals, and cosmetics contain extraneously added vitamins or vitamin-related compounds. Most of the vitamins are industrially produced and widely used in pharmaceuticals, foods and cosmetics.