Accessory food factors

Erganzungs-bandt tn. supplementary volume, supplement, -buch, n. supplemental volume, supplement, -farbe,/. complementary color, -ndhrstoff, -stoff, m. accessory food factor, vitamin, -werk, n. supplement, -wiokel, m. complementary angle. 

F.G.Hopkins. Need for accessory food factors in diet. 

The nutritional need for accessory food factors was first stated explicitly in 1905-1906, although the influence of diet in preventing or curing some diseases such as scurvy had long been known. The name vitamine was proposed in 1912, but the terminal e was dropped when it was realized that not all these compounds are nitrogenous bases. The vitamins serve as coenzymes in various metabolic processes, and the necessary quantities are usually supplied by an adequate diet or by synthesis by the intestinal flora. Vitamin deficiency can arise from a failure to absorb the compound from the gut. The symptoms of deficiency vary in different animal species, and not all the substances found necessary in other species have been shown to be essential for human nutrition. Vitamins are used for the prevention or cure of deficiency diseases and for some other pathological conditions,... 

At the time (1906), it was believed that diets were complete as long as they contained the appropriate chemical functional units. In particular, it was known that the indol unit was required for certain biological functions. Willcock and Hopkins were the first to show that diets had to contain specific molecules — in this case, tryptophane — and that other indol-containing compounds would not function in its place. This initial study focused Hopkins attention on the essentiality in diets of certain amino acids and led him to formulate his hypothesis of accessory food factors, later to be named vitamins. 30 Willcock, another of the Steamboat Ladies (see Chap. 6), received a D.Sc. from Trinity College, Dublin, on the basis of her research. 

The first of the accessory food factors to be isolated and identified was found to be chemically an amine therefore, in 1912, Funk coined the term vitamine, from the Latin vita for life and amine, for the prominent chemical reactive group. Although subsequent accessory growth factors were not found to be amines, the name has been retained - with the loss of the final -e to avoid chemical confusion. The decision as to whether the word should correctly be pronounced vitamin or veitamin depends in large part on which system of Latin pronunciation one learned - the Oxford English Dictionary permits both. 

When it was realized that milk contained more than one accessory food factor, they were named A (which was lipid-soluble and found in the cream) and B (which was water-soluble and found in the whey). This division into fat- and water-soluble vitamins is still used, although there is litfie chemical or nutritional reason for thus, apart from some similarities in dietary sources of fat-soluble or water-soluble vitamins. Water-soluble derivatives of vitamins A and K and fat-soluble derivatives of several of the B vitamins and vitamin C have been developed for therapeutic use and as food additives. 

Hume E and Krehs H (1949) Vitamin A Requirements of Human Adults. Report of the Vitamin A Sub-committee of the Accessory Foods Factors Committee. London Medical Research Council, His Majesty s Stationery Office. 

Medical Research Council Vitamin C Sub-committee ofthe Accessory Food Factor Committee (1948) Vitamin C requirements of human adults. Lancet 1, 835-58. 

This book is dedicated in gratitude to those whose painstaking work over almost 100 years since the discovery of the first accessory food factor in 1906 has established the basis of our knowledge, and in hope to those who will attempt to answer the many outstanding questions in the years to come. 

It may be observed in the story of many vitamins that clear evidence, in the light of present-day knowledge, of an accessory food factor was reported a considerable time before the relevant vitamin was discovered. Cod liver oil was a well-known remedy for rickets and osteomalacia centuries ago. Hess gives an interesting account of the historical side. Schabad (1909) and Schloss (1916) in their work on children established the effect of cod liver oil on the Oa and P retention. 

It was appreciated in the early part of the twentieth century that a diet containing the correct amounts of carbohydrate, fats, and protein was insufficient for good health. Other accessory food factors were required. The initially identified accessory substances were amines, and so these vital amines were called vitamines. When it became clear that not all accessory substances were amines, the name became vitamins. 

About this time the term vitamines , derived from vital amines , was coined by Funk to describe these accessory food factors, which he thought contained amino-nitrogen. It is now known that only a few of these substances contain amino-nitrogen and the word has been shortened to vitamins, a term that has been generally accepted as a group name. 

Although there had been a behef that the water-soluble B necessary for growth was identical with the antineuritic vitamin, people became aware of the possibility that vitamin B is not a single entity. In 1927, following the crystallization of the antineuritic vitamin, the British Committee on Accessory Food Factors distinguished the heat-labile and heat-stable components of vitamin B, and named the former Bi and the latter B2. 

This was only six years after the first statements about the accessory food factors now called vitamins. These factors were going to revolutionize nutritional thinking within a short time. The meager information about these new factors at that time prevented any consideration being given to them. Furthermore a lack of knowledge, even in the field of calorie requirements, caused much discussion of the figures used and has not been dispelled to the present time (Calorie Requirements, 1950. F.A.O. Report). 

Of the six vitamins regarded as essential accessory food factors (vitamins A, B, B2, nicotinamide, C and D), only vitamins A and D are insoluble in water. Presentation of fish-liver oils, rich in these two vitamins, as emulsions enhances the absorption of the vitamins, but such preparations are not always palatable. However, half a century ago Lester-Smith [170-172] observed the solubilization of vitamins A and D in soap solutions formed by the saponification of vitamin-containing oils. Vitamins E and K are also insoluble in water vitamin E is used in the treatment of habitual abortion, and vitamin K is employed to combat hypoprothrombinaemia. 

In an important paper, published in 1912, Hopkins showed the presence of accessory food factors in milk which were essential for the growth of rats. In 1915, these were resolved by McCollum and Davis into a fat-soluble A factor and a water-soluble B factor, and with them a third, the water-soluble C factor, was included by Harden and Zilva, in 1919. Since then the original A factor has been resolved into A and D by E.Mellanby, and the original B factor has been shown to be a mixture of several vitamins. 

Besidual Vitamins of the B Complex.— At least a dozen different accessory food factors have been referred to the B group in natural food sources, especially yeast. These include Bg, a thermo-labile avian growth factor (Williams and Waterman) Bg, an alkali-labile rat growth factor (Readers) and Bg, a thermo-stable and alkali-stable rat growth factor (Carter) H, an anti-dermatitic factor (Kuhn), identified with factor Y (Chick and Copping) and vitamin Bg. Rats require at least six different factors from the B complex including thiamine, riboflavin and adermine. 

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