The dosage of vitamin C necessary to maintain a level in the urine which could be detected using the 2,6-dichlorophenolindophenol assay was determined with undergraduate students. Students taking 250 mg daily did not excrete significant levels of vitamin C in their urine, while excretion increased at doses from 0.5 to 2 g. A 2 g daily dose caused detectable excretion from about 4 until 16 hr later, on both the first and eighth day. A dose of 500 mg taken every 12 hr led to continuously-detectable levels of vitamin C in the urine. The conclusion is that two conditions are necessary to elevate vitamin c excretion continuously: a dose of at least 500 mg and a dose every 12 hr. This is substantially higher than the U.S. recommended daily allowance and more frequent than administration being used in clinical trials.
KeywordsClinical Trial Undergraduate Student Human Urine Daily Allowance Detectable Excretion
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