The study by Padayatty et al. investigates the pharmacokinetics of vitamin C to determine whether plasma concentrations vary significantly with different routes of administration. The researchers used a depletion-repletion design with 17 healthy volunteers to measure plasma and urine vitamin C concentrations after oral and intravenous doses ranging from 0.015 to 1.25 g. They found that peak plasma vitamin C concentrations were significantly higher after intravenous administration compared to oral administration (P < 0.001), with the difference increasing with dose. For example, a 1.25 g oral dose produced mean peak plasma concentrations of 134.8 ± 20.6 μmol/L, while an intravenous dose produced 885 ± 201.2 μmol/L. Pharmacokinetic modeling predicted even higher peak plasma and urine concentrations for intravenous doses, with intravenous administration achieving up to 140-fold higher urine concentrations compared to oral doses. The study concludes that oral vitamin C produces tightly controlled plasma concentrations, whereas intravenous administration can achieve much higher concentrations, which may have antitumor activity. However, the clinical efficacy of vitamin C in cancer treatment remains uncertain due to the lack of high-dose patient data and the need for re-evaluation of its role in cancer therapy.The study by Padayatty et al. investigates the pharmacokinetics of vitamin C to determine whether plasma concentrations vary significantly with different routes of administration. The researchers used a depletion-repletion design with 17 healthy volunteers to measure plasma and urine vitamin C concentrations after oral and intravenous doses ranging from 0.015 to 1.25 g. They found that peak plasma vitamin C concentrations were significantly higher after intravenous administration compared to oral administration (P < 0.001), with the difference increasing with dose. For example, a 1.25 g oral dose produced mean peak plasma concentrations of 134.8 ± 20.6 μmol/L, while an intravenous dose produced 885 ± 201.2 μmol/L. Pharmacokinetic modeling predicted even higher peak plasma and urine concentrations for intravenous doses, with intravenous administration achieving up to 140-fold higher urine concentrations compared to oral doses. The study concludes that oral vitamin C produces tightly controlled plasma concentrations, whereas intravenous administration can achieve much higher concentrations, which may have antitumor activity. However, the clinical efficacy of vitamin C in cancer treatment remains uncertain due to the lack of high-dose patient data and the need for re-evaluation of its role in cancer therapy.