"It is important that the distinction between a pure vitamin and a vitamin complex be made clear. Vitamins are like other food elements in that in nature they are never found pure; they are found as “complexes,” that is, as mixtures of chemically related substances.
There is the same difference between [chemically] pure vitamin B and vitamin B complex as there is between refined starch and whole wheat flour. Both are carbohydrates. The starch may be chemically pure, but [precisely] because it is chemically pure, it is less wholesome than the whole wheat flour. No chemist is competent enough to catalog all the additions necessary to make the starch equivalent to the whole wheat, for the reason that all the cooperative nutritional factors in the flour probably have not been identified. That is why pure or synthetic vitamins are inferior to concentrates made from natural food sources.
They are cheaper, of course, since synthetic products can be put together in a chemical works, whereas the natural product must be laboriously gleaned from the food or food by-product source, which may be some such material as rice bran, wheat germ, etc.
All the known vitamins are now recognized as occurring in the form of “complexes.” It has also been found that the potency becomes less if the purification is carried too far for some, if not all, of the vitamins. That is significant, showing that these various factors of the complex cooperate with each other in producing the vitamin effect. It also explains the disappointing results with some of the pure or synthetic forms."
Examples of vitamins that are designed as whole-food complexes:
Cataplex A - made from foods naturally high in vitamin A and related cofactors; good for the eyes and the liver.
Cataplex B - made from foods naturally high in vitamin B4, plus choline and inositol; good for the heart, brain, and a sense of wellbeing.
Cataplex C - made from foods naturally high in vitamin C, like buckwheat leaves, peavine juice and mushrooms. Good to help carry more oxygen in the blood, promotes immune system and strengthens capillaries.