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 B6 4-pyridoxic acid. Several studies have shown that 4-pyridoxic acid is undetectable in the urine of vitamin B-deficient subjects, making it a useful clinical marker to assess the vitamin B status of an individual. Other products of vitamin B metabolism excreted in the urine when high doses of the vitamin have been given include pyridoxal, pyridoxamine, and pyridoxine and their phosphates. A small amount of vitamin B is also excreted in the feces. The classic clinical syndrome for vitamin B deficiency is a seborrhoeic dermatitis-like eruption, atrophic glossitis with ulceration, angular cheilitis, conjunctivitis, intertrigo, and neurologic symptoms of somnolence, confusion, and