Hypervitaminosis pyridoxine

Hypervitaminosis A, 25 789 Hypervitaminosis biotin, 25 800 Hypervitaminosis cobalamin, 25 804 Hypervitaminosis D, 25 792 Hypervitaminosis E, 25 794 Hypervitaminosis folic acid, 25 803 Hypervitaminosis K, 25 795 Hypervitaminosis niacin, 25 798 Hypervitaminosis niacinamide, 25 798 Hypervitaminosis pantothenic acid, 25 799 Hypervitaminosis pyridoxine, 25 799 Hypervitaminosis riboflavin, 25 797 Hypervitaminosis thiamine, 25 796 Hyphenated techniques... 

Hypervitaminosis Pyridoxine. A certain mystique has built up around this vitamin, resulting in individuals overdosing themselves with commercial vitamin supplements. Serious neurological problems have been seen in doses of 2-6 g/day for 2 0 months (62-64). Megadosing below 2 glday seems safe, but all of this information is based mostly on anecdotal reports. There is a Tolerable Upper Intake Level, but the UL to RDA ratio is a comfortable 50-60. 

Lack or deficiency of a V., as a result of unbalanced nutrition, leads to charaeteristic metabolic disturbances. Complete absenee of a V. leads to avitaminosis, with typical clinical symptoms. Relative deficiency of a V. causes hypovitaminosis. Such conditions are reversible by administration of the appropriate V. Excessive intake of certain V, e.g. V.A or V.D, can lead to hypervitaminosis. Formerly, V. were named after the diseases they cured, e.g. antiscorbutic V., antirachitic V, antiberiberi factor. Not all V., however, have such a pronounced specificity, and the clinical pictures of many avitaminoses and hypovitaminoses are complex and variable. A nomenclature based on letters of the alphabet was developed simultaneously the designations A, B, C, D and E were applied in the historical order of discovery. Subscripts were applied as more refined chemical analysis revealed that the originally isolated substances were in fact complex mixtures. This was especially true for the B vitamins. Partly because of confusion over the B complex , trivial names which give an indication of the chemical structure of the V. (e.g. pyridoxine or pyiidoxol for V.B() are now preferred. 

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