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> Tocopherol (vitamin E) and methyl naphthoquinone (equivalent of vitamin K) complete the list of the vitamins that are available from chemical manufacture. They are still little used. The former is essential for reproduction in rats, so that it has become known as the sex vitamin, but doctors are still uncertain whether it has any such value in human beings. The latter is unique: it is not vitamin K but is equally effective in decreasing the clotting time of blood.
The Unknowns. At least five other vitamins have been identified chemically,* but no one knows how many more there may be, or what they do. For the vitamins not yet identified, concentrates are made from a list of weird items reminiscent of a Chinese pharmacopoeia: yeast, wheat germ, defatted milk, rice polishings, grass juice and liver extract.
One thing about vitamins is definite. They are no substitute for food; they provide no energies, calories or body-building materials, are merely accessory to diet. But in many ways they are still mysterious—hence doctors still urge the necessity for balanced diets and warn against dependency on pills.
The drugstore pill-eater can ensue health by taking the entire list, but if he is to buy wisely he has much to learn of both chemistry and medicine. As with the patent medicines of a former day, the greatest harm is the waste of money.
* Except for vitamins A and D, which are not manufactured chemically, are sold only as concentrates from fish-liver oils. * The five: biotin, choline, inositol, para-amino-benzoic acid, folic acid.