megavitamin therapy

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The administration of supraphysiologic or in some cases ‘hyper-doses’—up to hundreds of times daily requirement—of vitamins, based on the belief that it will correct an unnamed disorder
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

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  
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

meg·a·vi·ta·min ther·a·py

(meg'ā-vī'tă-min thār'ă-pē)
Large doses of vitamins, minerals, and amino acids that are used as medications to treat physical and psychiatric illnesses.
Synonym(s): orthomolecular medicine.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012