per liter (µmol/L) once consumption exceeds 1,250 milligrams. As noted, government recommendations are a range of 40 to 110 mg/day and normal plasma is approximately 50 µmol/L, so 'normal' is about 25% of what can be achieved when oral consumption is in the proposed megadose range. Pauling popularized the concept of high dose vitamin C as prevention and treatment of the common cold in 1970. A few years later he proposed that vitamin C would prevent cardiovascular disease, and that 10 grams/day, initially (10 days) administered intravenously and thereafter orally, would cure late-stage cancer. Mega-dosing with ascorbic acid has other champions, among them chemist Irwin Stone and the controversial Matthias Rath and Patrick Holford, who both have been accused of making unsubstantiated treatment claims for treating cancer and HIV infection. Vitamin C mega-dosages are to a large degree discredited. There is no scientific evidence that vitamin C megadosage helps to cure or prevent cancer, the common cold, or some other medical conditions. Benefits are not superior when supplement intakes of more than 1,000 mg/day are compared to intakes between 200 and 1,000 mg/day, and so not limited to the mega-dose range. The idea that large amounts of intravenous ascorbic acid can be used to treat late-stage cancer is - some forty years after Pauling's seminal paper - still considered unproven and still in need of high quality research. However, a lack of evidence has not stopped individual physicians from prescribing intravenous ascorbic acid to thousands of people with cancer. Society and culture In February 2011, the Swiss Post issued a postage stamp bearing a depiction of a model of a molecule of vitamin C to mark the International Year of Chemistry. Brand names Vitamin C is sold around the world as a stand-alone product at amounts up to 1,000 mg and as part of fixed-dose combination products, under many brand names. Pharmacopoeias British Pharmacopoeia Japanese Pharmacopoeia Notes References Further reading External links 3-Hydroxypropenals Biomolecules Coenzymes Dietary antioxidants Dihydrofurans E-number additives Enediols Food antioxidants Furanones Organic acids Orthomolecular medicine World Health Organization essential medicines Wikipedia medicine articles ready to translate Ophthalmology drugs