Vitalism Vitamins

The calories provided by sugar are loaded with vital vitamins... 

Our word vitamin was coined m 1912 m the belief that the substances present m the diet that prevented scurvy pellagra beriberi rickets and other diseases were vital amines In many cases that belief was confirmed certain vitamins did prove to be amines In many other cases however vitamins were not amines Nevertheless the name vitamin entered our language and stands as a reminder that early chemists recognized the crucial place occupied by amines m biological processes... 

The compounds of the t/block elements show a wide range of interesting properties. Some are vital to life. Iron is an essential component of mammalian blood. Compounds of cobalt, molybdenum, and zinc are found in vitamins and essential enzymes. Other compounds simply make life more interesting and colorful. The beautiful color of cobalt blue glass, the brilliant greens and blues of kiln-baked pottery, and many pigments used by artists make use of d-block compounds. 

When acting as a methyl donor, 5-adenosylmethionine forms homocysteine, which may be remethylated by methyltetrahydrofolate catalyzed by methionine synthase, a vitamin Bj2-dependent enzyme (Figure 45-14). The reduction of methylene-tetrahydrofolate to methyltetrahydrofolate is irreversible, and since the major source of tetrahydrofolate for tissues is methyl-tetrahydrofolate, the role of methionine synthase is vital and provides a link between the functions of folate and vitamin B,2. Impairment of methionine synthase in Bj2 deficiency results in the accumulation of methyl-tetrahydrofolate—the folate trap. There is therefore functional deficiency of folate secondary to the deficiency of vitamin B,2. 

A component of the ribotide reductase complex of enzymes, protein Ba, has been shown to contain two non-heme iron atoms per mole (77). This enzyme plays a vital, albeit indirect, role in the synthesis of DNA. Curiously, the lactic acid bacteria do not employ iron for the reduction of the 2 hydroxyl group of ribonucleotides. In these organisms this role has been assumed by the cobalt-containing vitamin Bi2 coenzyme (18). The mechanism of the reaction has been studied and has been shown to procede with retention of configuration (19). 

Milk is an excellent source of calcium, phosphorus, riboflavin (vitamin B2), thiamine (vitamin Bl) and vitamin B12, and a valuable source of folate, niacin, magnesium and zinc (Food Standards Agency, 2002). In particular, dairy products are an important source of calcium, which is vital for maintaining optimal bone health in humans (Prentice, 2004). The vitamins and minerals it provides are all bioavailable (i.e. available for absorption and use by the body) and thus milk consumption in humans increases the chances of achieving nutritional recommendations for daily vitamins and mineral intake (Bellew et al., 2000). 

The term vitamin is a misnomer, the name means vital amines, and while vitamins are essential for life they are not, as was originally supposed, amines. Most vitamins were discovered as a result of a deficiency disease produced by a restricted diet. Long voyages on sailing ships with a diet composed of ship s biscuit, dried beans, dried peas and salted meat produced scurvy. In the worst cases the whole crew were affected, but the ship s officers tended to be less severely affected. 

The word vitamin is an abbreviation of the two words vital mineral. Vitamins were once considered to be those minerals that were vital for a healthy life. The modern meaning is somewhat more comprehensive. 

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