VITAMINE. — These are regulatory principles, for the most part chemically known, contained in animal and plant tissues used as food. The name “vitamines,” due to Funk, is the most widespread, although inappropriate because not all these principles contain nitrogen; they have also been called “accessory dietary factors” (Mc Collum), “cutonne” (Pugliese), “nutramine” (Abderhalden), and “completine” (R. Berg).
I. HISTORY
The history of vitaminology is recent, although as early as 1720 the Austrian Kramer had made interesting observations on the relationship between scurvy and diet. It generally begins with the observations of Lunin (1881) and of the Italians Coppola and Pasqualis (1895–96), which suggested that natural foods, such as milk, contained principles necessary for metabolic equilibrium and distinct from the known classes of foodstuffs. The fundamental observations of Eijkman date from 1897: he discovered the relationship between an exclusive diet of dehulled rice (as is customary in many regions of the Far East) and beri-beri; in 1906 Hopkins published exemplary studies on the insufficiency of synthetic diets, even when they fully met energy and amino-acid requirements. In 1910 Stefani advanced the hypothesis that pellagra depended on the absence from a maize-based diet of something “imponderable” yet necessary to the organism. In 1912 Holst and Froelich described the condition of experimental scurvy in the guinea pig, recognizing in it the deficiency of a factor of this kind, found especially in certain plant tissues and fresh animal organs, but absent from cereal grains; they thus placed the old empirical observations of sailors and explorers on a sound experimental basis. In 1914 Funk published a fundamental monograph on the V. and on the related deficiencies or “avitaminoses.” To complete these brief notes on the development of vitaminology, after recalling the work of Mc Collum and Davis, who distinguished the V. into water-soluble and fat-soluble (1915), it is necessary to add that Lorenzini and his collaborators, as early as 1917, had begun studying methods for the extraction and stabilization of the V. and had considered various therapeutic applications, recognizing the importance of those disvitaminoses linked to the organism’s inability to use the V. correctly, even when they are normally supplied by the diet. In particular, the study of such disvitaminoses, together with deficiency states caused by imbalance, is being pursued with special interest by the most modern lines of research. Chemistry has by now taken over vitaminological studies and, thanks above all to eminent chemists such as Windhaus, Karrer, Szent-György, Williams, R. Kuhn, etc., the synthesis of nearly all the V. known today has been achieved.There are at least 14 v., but in the syllabus presented by the “Council on foods and nutrition” of the “American Medical Association,” published in June 1946, only the manifestations of seven vitamin-deficiency states are noted—that is, only those avitaminoses that have been certainly observed in humans and are of dietary origin. Some of the omitted V. have been shown to be essential only under special experimental conditions. Since many V. body, they are ordinarily produced in sufficient quantities by intestinal bacteria. Sulfonamides, for example, which inhibit the growth of intestinal bacteria, may cause various forms of avitaminosis.
Today, in assessing the quantities of vitamins necessary in the diet, the tendency is to ensure a broad margin of safety, in order to prevent the possible onset of deficiency symptoms under unfavorable conditions. Vitamin-deficiency diseases are often the result of multiple factors, and the lack of V. in the diet is only one of their causes, as, for example, occurs in rickets; until a better understanding of the accessory causal factors has been achieved, a generous administration of V. is to be recommended as the only reliable means of prophylaxis, especially during periods of increased requirements and illness.
Alongside conditions of hypovitaminosis due to deficient vitamin ap-
port, deficiency conditions due to complete utilization may also be observed; thus, for example, a disorder of intestinal fat absorption may entail poor absorption of fat-soluble v., even though their dietary intake is entirely normal. The metabolic imbalance induced by vitamin deficiency may cause irreparable and irreversible lesions: Mouriquand called “paravitaminosis” the pathological condition represented by lesions resistant to administration of the specific V. It is now established that one deficiency aggravates another and that an adequate supply of V. enables the organism to maintain equilibrium with a lower protein intake.
II. DISTINCTIONS
The V. are commonly distinguished into fat-soluble, that is, bound to fats, soluble in them and extractable with fat solvents, and water-soluble, that is, soluble in aqueous media and extractable by aqueous or hydroalcoholic extraction.The most important fat-soluble V. are: 1) V. A or anti-xerophthalmic v., contained chiefly in cod-liver oil, raw spinach, butter, egg yolk, and fresh tomatoes; it is highly important for visual, anti-infective, and epithelial-protective functions; 2) the group of V. D, or calcium-fixing or antirachitic v., not widely distributed in nature; it is found chiefly in cod-liver oil; in the development of rickets, besides dietary deficiency of V. and lack of solar irradiation of the organism, the calcium-phosphorus balance in the diet also plays a role; 3) V. E or anti-sterility v., which promotes fertility in animals, is present in cereal embryos, green leaves, walnuts, and peas; it also appears to be a neurotropic factor of great importance; 4) V. K or antihemorrhagic v., whose deficiency produces hemorrhages and reduced blood coagulability: K_{1}, of plant origin, is found chiefly in green leaves, oats, and wheat; K_{2}, of bacterial origin, is found in the liver, having come from saprogenic intestinal germs; 5) the so-called V. F, an unsaturated fatty acid, whose deficiency produces chiefly disorders of cutaneous trophism.
The most important water-soluble V. are: numerous factors extractable from yeasts, which constitute the B_{1} complex; the many factors composing it, distinguishable according to their resistance to heating, are not yet all sufficiently known; the most studied are: 1) V. B_{1} or aneurin or thiamine, antipolyneuritic, a V. of fundamental importance, since an indispensable complex of enzymatic functions (decarboxylation, oxidation, phosphorylation) is centered around it; it promotes alcoholic fermentation and bacterial multiplication; as Williams says, it is one of the earliest inventions for the evolution of life; 2) V. B_{2} or riboflavin or lactoflavin, contained in lactic and butyric bacteria, egg white, and whey; it is antistomatitic, antieczematous, and perhaps also antipellagrous; 3) V. B_{6} or adermin or pyridoxine, contained in rice bran, egg yolk, and beef liver, it is antidermatitic; 4) V. PP, antipellagrous, nicotinamide, of fundamental importance in protecting the skin, mucous membranes, and nervous system, is a constituent of the active group of enzymes involved in oxidation-reduction processes (dehydrogenases); 5) V. B_{12}, active in doses of a few gamma (γ = one-thousandth of a milligram) against pernicious anemia; and, finally, 6) folic acid, against pernicious-anemia-like alimentary and pregnancy-related anemias; 7) pantothenic acid; 8) V. H or antiseborrheic v. or biotin. The following also belong to the water-soluble v.: 9) V. C or ascorbic acid, antiscorbutic; it is very widespread in the plant kingdom (especially peppers, lemons, and asparagus); it cannot be synthesized either by humans or by monkeys, which must therefore obtain preformed ascorbic acid from outside; the fundamental function of V. C is to transport hydrogen in the oxidation-reduction processes of cells; its requirement is increased in fever and in all infectious diseases that require an increased protective function of the adrenal glands; 10) V. P or citrin or capillary-permeability V. action; its action overlaps only partially with that of ascorbic acid, since it chiefly regulates vascular permeability.
All these exogenous regulators, introduced as such or as precursors (provitamins) that the organism can transform into v., are generally involved in vital processes fundamental to all cells. Some V. vegetative life; the connections of certain branches of dermatology and ophthalmology with vitaminology are also extensive. The relationship between V. and natural immunity has been much studied.
When dietary restrictions are imposed on a community for any reason, vitamin deficiency may cause more serious harm than the caloric reduction of the ration. The v., which are true plant hormones and often function as growth factors for the plants themselves, thus perform a function of fundamental importance in the rational nutrition of modern human beings (Virtanen), and constitute a broad and important, still developing chapter of the science of nutrition.
#### VITANDI: V. SCOMUNICA.