[i] Pauling stuurde een ingezonden brief naar het medisch-wetenschappelijke tijdschrift JAMA, naar aanleiding van een kritische bespreking van zijn boek over vitamine C en verkoudheid. Pauling schreef onder meer:
“I do not recommend doses of from 1 to 10 gm daily throughout life. Instead, I say that there is evidence that some people remain in very good health, including freedom from the common cold, year after year through the ingestion of only 250 mg of ascorbic acid per day” (Linus Pauling. Vitamin C and common cold. JAMA 1971; 216(2), 12 april, p. 332)
[ii] De veilige dosis van vitamine C is gesteld op maximaal 2 g per dag [Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids (2000) Institute of Medicine p 160-165. Over doses van 10-40 gram per dag is weinig bekend.]
Bijwerkingen van hoge doses vitamine C:
“People with hemochromatosis, glucose-6-phosphate dehydrogenase deficiency, and renal disorders may be particularly susceptible to the adverse effects of excess vitamin C intake and therefore should be cautious about ingesting vitamin C at levels greater than the RDA. Vitamin C may enhance iron absorption and exacerbate iron-induced tissue damage in individuals with hemochromatosis, while those with renal disorders may have increased risk of oxalate kidney stone formation from excess vitamin C intake.”
[Otten JJ, Hellwig JP, Meyers LD, eds; Dietary Reference Intakes: The Essential Guide to Nutrient Requirements, Washington, DC: The National Academies Press, 2006, p.205]
Vitamin C in overdosage may be associated with diarrhea and may predispose to renal oxalate calculi. A single 45 g dose of iv ascorbic acid, a metabolic precursor of oxalate, administered to a 58 year old woman as adjuvant therapy for primary amyloidosis and the nephrotic syndrome, resulted in the development of acute renal failure secondary to tubular obstruction, with calcium oxalate crystals and a serum ascorbic acid level of 15.4 mg/dL (normal 0.4-2.0 mg/dL). She was hemodialyzed, and later developed ventricular fibrillation and died.
[Ellenhorn, M.J. and D.G. Barceloux. Medical Toxicology - Diagnosis and Treatment of Human Poisoning. New York, NY: Elsevier Science Publishing Co., Inc. 1988., p. 557]
Large doses are reported to cause diarrhea and other gastrointestinal disturbances. It has also been stated that large doses may result in hyperoxaluria and the formation of renal calcium oxalate calculi, and ascorbic acid should therefore be given with care to patients with hyperoxaluria. Tolerance may be induced with prolonged use of large doses, resulting in symptoms of deficiency when intake is reduced to normal. Prolonged or excessive use of chewable vitamin C preparations may cause erosion of tooth enamel.
[Sweetman SC (ed), Martindale: The Complete Drug Reference. London: Pharmaceutical Press (2009), p.1984.]
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