thiamin

thiamin.

See thiamine.

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thiamine [thi´ah-min]

vitamin B₁, a component of the B complex group of vitamins, found in various foodstuffs and present in the free state in blood plasma and cerebrospinal fluid. Deficiency results in neurological symptoms, cardiovascular dysfunction, edema, and reduced intestinal motility. See also vitamin.

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thiamin, thiamine

vitamin B₁; a component of the B complex group of vitamins, found in various foodstuffs and present in the free state in blood plasma and cerebrospinal fluid. The pharmaceutical products are thiamin hydrochloride and thiamin pyrophosphate.

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thiamin nutritional deficiency

an unlikely event in food animals with two exceptions: the secondary deficiency caused in horses and pigs by thiaminase in bracken and the primary deficiency in horses fed a diet almost entirely of turnips. In companion animals, the deficiency is much more common. Dogs, and particularly cats, fed diets in which thiamin has been destroyed, usually by excessive heat in processing but also by the inclusion of raw fish of certain marine species or sulfur dioxide as a food preservative, will develop signs of deficiency which include ataxia, mydriasis and convulsions.

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megavitamin therapy

The administration of excess or 'hyper-doses' of water-soluble vitamins, either physician-guided–eg, to treat neuropathies, or self-prescribed by health-food advocates. See Decavitamin, Orthomolecular medicine, Vitamin.

Megavitamins, adverse effects  

Thiamin CNS hyperresponsiveness–convulsions, Parkinson's disease–thiamin antagonizes l-dopa, sensory neuropathy–destruction of dorsal axon roots

Niacin/nicotinic acid & niacinamide/nicotinamide Exacerbation of asthma–histamine release, cardiac disease–arrhythmias, GI symptoms, eg nausea, vomiting, diarrhea, anorexia, DM–hyperglycemia, gout–↑ uric acid, liver disease–enzyme leakage, hepatocellular injury, portal fibrosis or massive necrosis, cholestatic jaundice, peptic ulcer disease–histamine release, ↑ acidity, skin disease

Vitamin B₆ Paresthesia, headaches, asthenia, irritability

Vitamin C ↑ Iron absorption, possibly iron overload, evoking diarrhea, renal calculus formation and possibly inhibiting the bacteriolytic activity of neutrophils, G6PD deficiency–↑ red cell lysis, megaloblastic anemia–↓ vitamin B₁₂ absorption, nephrolithiasis–oxaluria Diagn Clin Testing 1990; 28:27