CHAPTER 1<br >Vitamins: What They Are<br >and What They Do<br > Despite all the talk about vitamins today， few people actually<br >know what they are and why they are so important. Vitamin re-<br >search goes on constantly， new discoveries are reported from<br >time to time， but scientists are all too aware that they don t know<br > all of the facts about all of the vitamins. Today 15 vitamins have<br > been recognized and analyzed. Scientists believe that again as<br > many probably exist and are essential for our health.<br > Vitamins are organic food substances--that is， substances<br > that occur naturally only in living things， plant or animal. They<br > exist in foods in minute quantities; they are absolutely necessary<br > for proper growth and the maintenance of health. Plants manu-<br > facture their own vitamins. Animals obtain theirs from plants or<br > from other animals that eat plants. Some animals manufacture in<br > their own bodies some of the vitamins they need.<br > It was around the turn of the century that someone first<br > suspected there might be more in foodstuffs than fats， proteins，<br > carbohydrates， and minerals. Laboratory experiments showed<br > that even when all those elements were present in the diet， labo-<br > ratory animals could still die of malnutrition. Scientists began to<br > search for this important missing link. They discovered vi-<br > tamins. The name comes from vita (life) plus amine (the<br > chemical compounds that were originally thought to be vi-<br > tamins). 3<br >