Examine publishes rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies each month, available to all Examine Members. Click here to learn more or log in.

In this article

Putting the “C” in Cancer

Decades ago, seminal research looked at vitamin C cancer benefits ... then research stopped. Researchers are back at it, with this trial looking at vitamin C for specific types of lung and brain cancer.

Study under review: O2·- ,– and H2O2-Mediated Disruption of Fe Metabolism Causes the Differential Susceptibility of NSCLC and GBM Cancer Cells to Pharmacological Ascorbate


In 1972, Ewan Cameron proposed in a brief letter[1] to The Lancet that ascorbic acid, also known as vitamin C, could be useful in suppressing cancer. In 1976[2], he famously teamed up with Linus Pauling to investigate this matter, publishing a clinical trial finding that 10 grams of ascorbic acid given intravenously for around 10 days, followed by 10 grams per day orally, prolonged the survival of terminal cancer patients. However, follow up research in the late ‘70s[3] and ‘80s[4] using 10g oral ascorbic acid failed to replicate this effect. These failures reduced interest in ascorbic acid’s effects on cancer.

In the mid-1990s, researchers argued[5] that this reduced interest was premature. They hypothesized that intravenous ascorbic acid could reach levels toxic to cancer cells. They also cited a host of evidence suggesting that ascorbic acid would not be harmful to normal cells due to metabolic differences with cancer cells involving hydrogen peroxide generation. Since ascorbic acid could potentially kill cancer cells selectively, they thought that intravenous ascorbic acid’s effect on cancer should be investigated.

In 2004, their arguments were bolstered[6] by research that found a reason for the failure to replicate Cameron and Pauling’s initial paper. These researchers found that oral vitamin C was unable to reach concentrations high enough in the plasma to have antitumor activity. However, intravenous dosing could, in theory, reach such levels. The Cameron and Pauling study may have worked because they started out with intravenous treatment. The replications, however, used only oral ascorbic acid, which can’t reach levels high enough to kill cancer cells.

This finding renewed interest in ascorbic acid’s effect on cancer, and research again picked up. In vitro test tube research found that ascorbic acid can kill pancreatic cancer cells[7] with a mechanism dependent on hydrogen peroxide production. A similar effect, also dependent on hydrogen peroxide, was seen in ovarian cancer[8].

The pieces of the puzzle started falling into place. Ascorbic acid seemed to selectively kill cancer cells over normal cells through a hydrogen peroxide-dependent mechanism. But some questions remain. How could this mechanism explain the selectivity? And would high dose intravenous vitamin C be safe and possibly effective in humans with cancer? The goal of a recently published study was to explore these questions through a series of preclinical and clinical experiments.

Linus Pauling and others found that ascorbic acid (vitamin C) improved outcomes in terminal cancer patients. Replications of these experiments failed, though. This may have been due to the early experiments using intravenous ascorbic acid, which is the only way to elevate vitamin C to levels toxic to cancer cells. The later experiments used oral ascorbic acid. Recently, interest in ascorbic acid’s effect on cancer has been renewed. While it’s known that ascorbic acid’s selective cancer-killing involves hydrogen peroxide production, the details of the mechanism aren’t well-understood.

Who and what was studied and what were the findings?

Become an Examine Member to read the full article.

Becoming an Examine Member will keep you on the cutting edge of health research with access to in-depth analyses such as this article.

You also unlock a big picture view of 400+ supplements and 600+ health topics, as well as actionable study summaries delivered to you every month across 25 health categories.

Stop wasting time and energy — we make it easy for you to stay on top of nutrition research.

Try free for two weeks

Already a member? Please login to read this article.

What does the study really tell us?

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

The big picture

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

Frequently asked questions

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

What should I know?

Become an Examine Member to unlock this article.

Free 2-week trial »

Already a member? Please login to read this article.

Other Articles in Issue #31 (May 2017)

  • Does vitamin D supplementation fight off the common cold?
    Anecdotally, vitamin D is known for "immune supporting properties". But many people just want to know if it helps prevent the common cold. This meta-analysis looked at the evidence.
  • Interview: James Krieger, MS
    For a good dose of realism, on topics ranging from insulin and fat loss myths to the most important factors in weight training, there aren't many better sources than James Krieger.
  • Can a shot of vinegar reduce blood glucose levels?
    Medications and supplements aren't the only ways to address blood sugar regulation. This meta-analysis looked at all the vinegar and blood sugar trials conducted to date.
  • Throwdown, round 2: plant vs. animal protein for type 2 diabetes
    In round one of this fight, an earlier study showed that a diet with proteinrich plants didn't provide a metabolic advantage. Round two explores metabolic impacts from a different angle: amino acid composition of plant versus animal protein
  • Interview: Sohee Lee
    Dieting is often equated to a focus on calories and nutrients, but an arguably bigger factor is the psychology of eating. We delve into that with Sohee.
  • Can omega-3s prevent migraines?
    Chronic migraine is a pain, both literally and figuratively, especially since it doesn’t have many good prevention methods. Could omega-3 supplementation help?
  • Beating postpartum blues with amino acids and antioxidants
    The more serious condition of postpartum depression is often preceded by the very common and short-lived postpartum blues. A specific combination of supplements was looked at for prevention of the postpartum blues.