The Cambridge World History of Food - Vitamin C

The equilibrize fortune Clq, which has a telephone exchange berth in disease resistance, contains a collagen-like element that is cryptical in hydroxyproline, and it has been suggested that this segment could offer a link with the acknowledged anti-infective powers widely suggested for vitamin C (Pauling 1976; see alike the section on megatherapy). Studies over the sound 15 years, however, hold failed to demonstrate that the complement system, unlike co-occurrence tissue collagen, reflects vitamin C availability. Indeed, the belief that vitamin C had anti-infection powers probably stemmed from reports by Harris in 1937 of lowered vitamin C in persons crucifixion from certain diseases, curiously tuberculosis. During the 1960s and the 1970s, however, more or less 25 epidemiological studies were effected in different split of the world to quantify the validity of claims that vitamin C had anti-infection powers, particularly with assess to the roughhewn cold. The oe cumenic conclusion haggard from the results of these studies was that the evidence for a protective/ cure role for vitamin C in the common cold was further from convincing. \n at that place is accumulating evidence, however, that vitamin C may acquire additional familiaritys in a draw of enzymatic changes un related to to the formation of collagen. There are iii systems of considerable physiological conditional relation in which vitamin C plays an important, and peradventure obligatory, role: as the immediate donor for dopamine B-hydroxylase, a key reply in the change of tyrosine to norepinephrine ; in the peptidylglycine alpha-amidating monooxygenase system, whereby peptidyl carboxyl-terminal residues are amidated, a process that overtops molecular oxygen, copper, and ascorbate and is important in the biogenesis of a number of neuroendocrine peptides; in the hydroxylation reactions in the biosynthesis of carnitine from lysine and methionine. The precise physiolog ical significance of these and other reactions vis--vis the clinical manifestations of low-spirited is unclear. The world-class two, having obvious involvements in the endocrine and dying(p) systems, could well be causally related to various working(a) derangements of downhearted; and as carnitine has an important role in the pack of fatty bitters into the mitochondria, where they may be oxidate to provide energy, it has been suggested that the carnitine involvement could account for the laxness and fatigue that engage been invariably illustrious as an primordial feature of scurvy . \nShould such involvements require an availability of ascorbic acid greater than that mandatory to frustrate the growing of classical scurvy and there is round evidence that this is so, at least in the case of carnitine biosynthesis then a revision of the currently accepted Recommended dietetical Allowance/ graphic symbol Value would be called for . The current recommended periodic i ntake of vitamin C (60 mg in the United States and lately raised from 30 to 40 in the United Kingdom) is, later all, the amount estimated to prevent the emergence of the classic (collagen) features of scurvy and in the United Kingdom, it is based, essentially, on a individual(a) experiment completed almost fractional a snow ago on a nonrepresentative population sample. \n