The vitamin B complex
Discovery of thiamin as an essential food factor for prevention of the disease, beriberi, began the fascinating advances in nutrition research, which during the first half of the 20th century led to the identification of all currently known vitamins. Descriptions of beriberi by the Chinese date back to about 2600 B.C., and some of the earliest attempts to treat the disease were reported from Japan and the Philippines. A medical officer in the Japanese Navy, Takaki, is credited with the recognition of the causal relationship of diet to this disease. In the 18808 Takaki, alarmed by the high incidence of beriberi among the Japanese sailors, compared their diets with that of the British Navy, which did not have this problem. Convinced that the higher protein content in the diets of the British prevented beriberi, he revised the Japanese ration to include more meat, vegetables, and "condensed" milk) and 1 E1313 rice. The new diet was tested on a special training ship which returned from a 287-day voyage with a report of onlva few cases of beriberi and no deaths. The men who developed the disease had refused to eat the meat and milk.
The next significant milestone in the history of thiamin, and of nutrition in general, was achieved by two Dutch physicians who worked in the Dutch East Indies, the present Indonesia. In 1897 Eijkman noted that poultry fed table scraps of polished rice from the prison hospital developed polyneuritic symptoms similar to those of his patients suffering from beriberi. Brown rice or addition of rice polishings to the diet cured the condition in the chickens. Eijkman suggested that polished rice contained a "toxic factor," which was "neutralized" by the polishings. A few years later Grijn concluded that natural foods contained an unknown food factor that prevented beriberi and that this factor was lacking in polished rice. After he had produced polyneuritis in birds on a diet consisting mostly of starch, he showed that they could be cured by other foods as well as by rice polishings.
Following these discoveries many workers began to observe a variety of symptoms due to deficiencies among peoples ,~th different dietary patterns, and in animals fed diets of different compositions. It thus became evident that foods contain a number of the so-called accessory factors, later called vitamines by Funk. The first important breakthrough toward the eventual separation and identification of individual vitamins came in 1916 when McCollum and Davis recognized that milk contained at least two factors required for grovlth-one in the milk fat namedfat-soluble A and another in the liquid portion of milk designated as water-soluble B. This established the practice of using the alphabet to name newly discovered vitamins before their chemical structures were known.
The search for the identity of the wa ter-soluble antiberiberi factor soon led to another major discovery. Several independ renresearch groups observed that the antiberiberi activity of their partially purified preparations was destroyed by heating, although its grovnh-promotina activity remained. The antiberiberi factor became
known as Bland the heat-stable factor as. This was the, beginning of distinctions in a group of vitamins, which have been referred to as the vitamin B complex. The group L'lcludes eight distinct vitamins, which are discussed indi'idually in the following sections
