Megadoses

The solubility (or insolubility) of different vitamins is of concern in nutrition. Molecules of vitamins B and C contain several —OH groups that can form hydrogen bonds with water (Figure 10.3). As a result, they are water-soluble, readily excreted by the body, and must be consumed daily. In contrast, vitamins A, D, E, and K, whose molecules are relatively nonpolar, are water-insoluble. These vitamins are not so readily excreted they tend to stay behind in fatty tissues. This means that the body can draw on its reservoir of vitamins A, D, E, and K to deal with sporadic deficiencies. Conversely, megadoses of these vitamins can lead to very high, possibly toxic, concentrations in the body. 

Parenteral)-comb. Survitine (Roche Nicholas)-comb. Megadose (Arco) combination preparations... 

Pool concentration of a substance that exceeds the threshold - for example megadose vitamin C - or substances that are excreted unchanged because they cannot be metabolised, such as sugar alcohols, or compounds that are not biologically essential, such as carcinogens, bacterial toxins and some minor plant constituents, are also bioavailable (and thus bioactive) in that they have a metabolic impact, even if this is only the stimulation of detoxification processes, or the use of energy for their excretion. 

To administer such large doses, the authors had to have the atropine solutions prepared in a more concentrated form. The new injectable ampoules contained 50 mg per cc instead of the usual 2 or 5mg. These megadoses of atropine, and the claim that the resulting coma and delirium could be reversed by 4 mg of a dmg known to be ineffective in treating atropine toxicity, might have caused their reports to be r arded as balderdash by some readers. 

Complementary and alternative medicine CAM. Forms of treatment that are used in addition to (complementary) or instead of (alternative) standard treatments. These practices are not considered standard medical approaches. CAM includes dietary supplements, megadose vitamins, herbal preparations, special teas, massage therapy, magnet therapy, spiritual healing, and meditation. [NIH]... 

Long-term megadoses (2-6g over more than 2 mo) may produce sensory neuropathy (reduced deep tendon reflexes, profound impairment of sense of posifion in disf al limbs, gradual sensory af axia). Toxic sympf oms subside when drug is discon-finued. 

Death in laboratoiy animals has been reported in studies of acute-duration however, no studies were located for oral exposures of an intermediate and chronic-duration to HDl. Based on the information available, large, single megadoses of HDl (i.e., >940 mg/kg) administered to rats orally were associated with increased mortality, while lower single doses (<620 mg/kg) or lower multiple doses were associated with little or no mortality in rats. 

It is unclear what the precise effects of HDl are on the respiratory tract after oral exposure. In the studies that were examined, any effects on the respiratory tract were a result of megadoses of HDL In many cases, these doses resulted in death, with congestion of the lungs, peribronchial edema, altered respiration, and other non-specific respiratory symptoms (Haskell Laboratory 1946, 1961). No histopathology was performed on the lungs in these studies, so it is not possible to speculate about what was occurring at the cellular and molecular level in these tissues. 

Doses of melatonin as low as 3 mg (if given during the day) can produce increases in blood levels of melatonin that are 50 times higher than normal levels. Thus, megadose pills offered by some health food stores may cause melatonin concentrations that are vastly in excess of what is needed to affect sleep or biological rhythms. Melatonin is metabolized by the liver fairly quickly, so that half of the ingested melatonin is eliminated from the body within an hour of taking it, and an entire 3 mg dose is eliminated in 6 to 10 hours. 

Johnston CS, Yen MF. Megadose of vitamin C delays insulin response to a glucose challenge in normoglycemic adults. Am J Clin Nutr 1994 60(5) 735-8. 

Hinz B, Hirschelmann R. Dexamethasone megadoses stabilize rat liver lysosomal membranes by non-genom-ic and genomic effects. Pharm Res. 2000 17 1489-1493. 

Each E, when the intake is null or insufficient, generates a disease, Increasing its quantity up to the required daily allowance (DA), the disease disappears. However, when E is given in excess it reaches the toxicity limit (TL). In case of vitamins and some minerals RDA are well defined, whereas TL is sometimes less clear, and the tendency is to misuse both in megadoses,... 

Oxidized folate is not only metabolically dead buyt may even be neurotoxic. For example, a patient with epilepsy who has not had a convulsion in years because dilantin has produced complete control, can be thrown into an immediate convulsion with a megadose of folic acid, because folic acid and dilantin compete for absorption at the brain cell surface, and too much oxidized folic acid will block the ability of the brain cell to take up dilantin, similar to the competition between dilantin and folic acid for uptake by the gutcell (22). 

Herbert, V., Jacob, E., Wong, K. T. J., and Pfeffer, R. D., Low serum vitamin B12 levels in patients receiving ascorbic acid in megadoses Studies concerning the effect of ascorbate on radioisotope vitamin B12 assay. Am. ]. CUn. Nutr. 31, 253-258 (1978). 

B.O.N. (Doms-Adrian)- Evitina (CT) Megadose (Arco) comb. 

Pauling finally wearied of trying to convince medical professionals about the benefits of megadoses of vitamin C and took his case directly to the public. His book, Vitamin C and the Common Cold, was a best seller. Sales of the vitamin soared. Nevertheless, his dispute with physicians persisted, with Pauling advocating for huge doses of vitamin C and the medical profession pooh-poohing his ideas. 

In addition, megadoses of zinc of up to 5 g per day (40) or chronic dosing with "therapeutic" amounts of zinc, 150 mg of zinc daily for 1 to 2 years (41), have been associated with overt copper deficiency anemias. 

In conclusion, we have found that the presently set Recommended Dietary Allowances for riboflavin for women are inadequate even when they are not exercising, and that their riboflavin requirements are Increased by exercise. Weight reduction per se does not have an effect on riboflavin requirements. However, women who are exercising and on a weight reduction diet may get an inadequate amount of the vitamin because of their restricted food intake. We have no evidence, at least in the U.S., that athletes are at risk for clinical riboflavin deficiency. We do not think that it is necessary for those engaged in exercise to take megadoses of this B vitamin or of other B vitamins. 

Deficiencies of enzymes involved in the transformation of the vitamin pantothenic acid (64) into the cognate coenzyme forms (66, Fig. 7) result in severe developmental and neurological deflcits that affect few human patients (34, 72). Therapy with megadoses of pantothenic acid has been advocated, but their efficiency has yet to be demonstrated by stringent clinical studies (73). 

EXCESS There is concern about the possibility that certain susceptible individuals may develop renal stones or hemolytic anemia from megadoses of vitamin C. 

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