What are vitamins and carotenoids?
Although vitamins do not share a common chemistry, they share certain characteristics. They are all organic nutrients that are necessary in small amounts for normal metabolism and good health. Most vitamins must be provided by the diet or by supplements, but three vitamins (D, K and the B-vitamin biotin) can be manufactured in the body from non-dietary sources. Vitamins are not sources of energy as are carbohydrates, fats and proteins. Instead, vitamins serve as chemical partners for the enzymes involved in the body’s metabolism, cell production, tissue repair and other vital processes. Vitamins are either fat-soluble or water-soluble. The fat-soluble vitamins, which include A, D, E and K, are absorbed by the body using processes that closely parallel the absorption of fat. They are stored in the liver and used up by the body very slowly. The water-soluble vitamins include vitamin C and the B vitamins. The body uses these vitamins very quickly. Excess amounts are eliminated in urine. T
