are important, indeed literally vital, constituents of foodstuffs, but were not discovered until early in the 20th century and have not yet been fully explored.
They betrayed their presence through illnesses befalling groups of people who for one reason or another were deprived of one of them. The prevalence of scurvy, which results from a deficiency of vitamin C, might well have started the process of discovering the vitamins. But scurvy was a special problem that arose mainly on long sea voyages and seldom affected the population at large. In general it would be true to say that most people in Europe, up to the 19th century, obtained what vitamins they needed from their diets, even if these diets were rather monotonous. However, the advent of processed foods in the 19th century brought with it, along with some advantages, new risks of vitamin deficiency, and set the stage for serious and systematic work on the causes of such deficiency diseases as beriberi and pellagra.
The roller milling of flour was introduced in Hungary in the 1840s and soon spread all over Europe and N. America. For the first time it was possible to make really white flour at a low cost. The public took to the new inexpensive white bread with enthusiasm, and the extracted bran was fed to the animals. But the bran contained most of the valuable B vitamins of wheat, notably thiamin and niacin, the lack of which causes both beriberi and pellagra. Although these diseases seldom occurred in an acute form in Europe, standards of health declined.
Gail Borden's invention of sweetened, condensed milk in the 1850s also caused problems. This product has lost most of its vitamins A and D, which are needed to ward off xerophthalmia (an eye disease) and rickets. Rickets became common in the cities, but the explanation was not immediately apparent. Nowadays condensed milk has vitamins added.
In Asia, the introduction of ‘polished’ rice, with the bran rubbed off to leave the grains attractively white, left many people exposed to beriberi, resulting from an inadequate supply of thiamin. An outbreak of the disease in the Japanese navy in the early 1880s raised a suspicion that some dietary deficiency was responsible for the disease. In 1886 the Dutch East India Company sent an expedition to Indonesia to find the cause, and this had good results. In 1897, after eight years' work, Christian Eijkman established that polished rice was deficient in some substance, though he could not find what this was. In 1901 his colleague Gerrit Grijns discovered that this substance existed in rice bran.
The substance was recognized as essential to health, in addition to the traditional trio of protein, carbohydrates, and fat. So it was at first called ‘the accessory substance’ or ‘the accessory food factor’, in the singular. Casimir Funk, in Warsaw in 1912, extracted it in an impure form; it was what we now call thiamin. By this time it was clear that more than one such substance existed. Funk mistakenly thought that all the accessory food compounds were amines, a type of nitrogen compound, and coined the term ‘vitamine’ for them because they were vital to health. When this was found to be wrong the final ‘e’ was dropped, and the modern word ‘vitamin’ was the result.
Scientists had still to take one important step; they had to advance from the knowledge that such things as vitamins existed, and in what they were to be found, to knowing what they actually were. By 1915 the Americans McCollum and Davis had proved that there were at least two, which they called A and B, and the process of isolating them began.
Vitamin C was proved to exist by a long series of experiments on guinea pigs begun in 1907 by the Norwegians Holst and Frïlick. Actually they were trying to induce beriberi, but the animals went down with what was obviously scurvy. (This was a double fluke. Guinea pigs, apes, monkeys, and vampire bats are the only animals apart from humans which cannot make their own vitamin C.) The vitamin was isolated in 1925, by the Hungarian researcher Albert Szent-Györgi.
Vitamin D was discovered and named by McCollum in 1921; and vitamin E by Evans and Bishop in 1922, though it was not isolated till 1935.
This system of identifying vitamins by letters has now lost its original neat pattern as a result of more recent discoveries. Vitamin B has been divided into B1 (thiamin), B2 (riboflavin), B6 (pyridoxine), and B12 (cyanocobalamin), the gaps in the sequence indicating substances which were thought to have been B vitamins and then found out not to be after all. Niacin or nicotinic acid, although a member of the B group, has no number; for some time it was confused with thiamin until it was shown that only niacin prevents pellagra. Folic acid, biotin, and choline also belong to the B group but do not have numbers. The former vitamin F has been reclassified as an essential fatty acid (see fats and oils). The letter G was once given to riboflavin, now B2.
One other vitamin has a letter: vitamin K, a substance required for the clotting of blood. The letter stands for the German word ‘Koagulation’.
Vitamin P is a name sometimes given by health food enthusiasts to rutin, a substance found in citrus fruits. Orthodox scientists do not believe that it is necessary to health.
Vitamins may also be classified into two groups: fat soluble and water soluble. Fat soluble vitamins are found in fatty and oily foods. They are vitamins A and D, both found in liver, oily fish, and dairy products; vitamin E, in many vegetable foods, especially wheatgerm, and milk; and vitamin K, widely present in many vegetable foods. Because these vitamins are insoluble in water, they tend not to be lost in cooking. Water-soluble vitamins are the B group, found in yeast, wheatgerm, cereal products, meat, and fish; and C, found in fresh fruits, vegetables, and milk. These are easily lost in food preparation; vitamin C is particularly evanescent, being destroyed by exposure to light, heat, or air.
Two vitamins can be acquired from sources other than those described above. Vitamin A can be made in the body from carotenes, the common yellow plant pigments found in leafy vegetables (and, of course, carrots). Vitamin D is made in the skin when it is exposed to sunlight.
Ralph Hancock is an encyclopedist with a special interest in food history and food science.
