Vitamin C megadosage 6-8 g/day. As of 2014, at least 16 studies had found that vitamin C supplements did not prevent the common cold and had minimal effect at best in shortening cold lengths. Vitamin C megadosage Vitamin C megadosage is a term describing the consumption or injection of vitamin C (ascorbic acid) in doses well beyond the current Recommended Dietary Allowance of 90 mg/day, and often well beyond the Tolerable upper intake level of 2,000 mg/day. There is no scientific evidence that megadosage helps to cure or prevent cancer, the common cold, or a variety of other medical conditions. Historic advocates of
Vitamin A Vitamin A Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids (most notably beta-carotene). Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision. Vitamin A is needed by the retina of the eye in the form of retinal, which combines with protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light (scotopic vision) and color vision. Vitamin A also functions in a very different role as retinoic acid (an irreversibly oxidized form of