Dr. Levine, one of the world's experts on vitamin C metabolism, noticed that the plasma vitamin C levels of the 30 healthy volunteers in the Podmore study were 50 M at the beginning of the study before any supplemental vitamin C was given. Therefore, supplementation with 500 mg per day of vitamin C could not have further increased lymphocyte vitamin C levels. Unfortunately, the authors of the Nature study did not measure lymphocyte vitamin C levels in their volunteers. The study by Podmore and colleagues and their conclusion that vitamin C is harmful are compromised by unproved assumptions, an unacceptable study design, and highly inaccurate measurements. Hundreds of scientific studies strongly suggest that vitamin C helps reduce the risk of cancer and has important health benefits beyond preventing scurvy.
Additional studies are likely to find more benefits.
It would be tragic if people stopped taking vitamin C supplements, or decreased their intake of fruits and vegetables, based on this single, flawed study.