Time to re-examine vitamin C in the treatment of cancer

While it has been known for some time that vitamin C prevents scurvy, just how much of it is necessary for good health remains uncertain. In this issue of CMAJ, Sebastian Padayatty and Mark Levine review how understanding of the absorption and metabolism of vitamin C is improving and suggest that the 2 routes of administration are not equivalent.

The authors tie this finding to one of the durable controversies in medicine: that cancer can be treated with vitamin C. Although early optimism for this theory was prompted by remissions observed in a few patients with advanced, untreatable cancer, randomized controlled trials failed to support the theory. One of the principal criticisms of vitamin C treatment is that the early trials involved intravenous administration and the later ones, oral. Padayatty and Levine suggest that, in light of new pharmacokinetic data, the speculative use of vitamin C in pharmacological doses to treat cancer should be re-evaluated.

�The cause of cancer patients will be better served if advocates and sceptics concerning the efficacy of vitamin C re-examine these issues with both open minds and scientific rigour,� state the authors. In a related commentary, John Hoffer reflects on the need for �rules of engagement� in the debate between alternative and clinical medicine, to ensure that alternative therapies are appropriately evaluated.

Proof versus plausibility: rules of engagement for the struggle to evaluate alternative cancer therapies
-� L.J. Hoffer

Dr. Hoffer is with the Lady Davis Institute for Medical Research in Montreal. He can be reached at 514-340-8260

New insights into the physiology and pharmacology of vitamin C
-� S.J. Padayatty, M. Levine