Why Vitamin C? Cancer Fighting Properties

Ewan Cameron, Ava Helen and Linus Pauling. Glasgow, Scotland, October 1976.

[An analysis of Ewan Cameron and Linus Pauling’s book, Cancer and Vitamin C. This is part 2 of 9.]

In their 1979 book, Cancer and Vitamin C, Ewan Cameron and Linus Pauling argued that vitamin C could be used to effectively treat cancer. With such a bold claim having been issued, vitamin C now needed to do a lot of heavy lifting. More specifically, Pauling and Cameron needed to prove that vitamin C could a) effectively treat cancer and also b) do so better than other substances being used to treat and cure cancer. As such, the authors devoted nearly half of their book to exploring vitamin C’s unique properties, with particular attention naturally paid to its cancer-fighting abilities.

In doing so, Cameron and Pauling first examined known cancer-causing agents on the cellular level and then investigated how vitamin C interreacted with these agents. One such substance was the enzyme hyaluronidase. When Pauling and Cameron were writing their book, it was widely recognized that certain malignant tumors released this enzyme and that, when exposed to healthy tissues, the enzyme would break down the glycosaminoglycans, which might be likened to the “cement” that makes tissues strong. As the cement became weaker, the tissues grew more vulnerable to being penetrated by cancer cells. By extension, it was believed that hyaluronidase promoted the spread of malignant cells within the body. It was also suspected that cancer cells released a different enzyme, collagenase, which would break down the collagen in tissues, further weakening cells and making them more susceptible to disease.

Having established this, Pauling and Cameron then illustrated the role that vitamin C could play in obstructing this process. Studies had found that vitamin C naturally helps to produce a hyaluronidase inhibitor, which in effect blocks the enzyme and stops the destruction of the tissue cement. Furthermore, vitamin C is known to be a necessary component for the building of collagen, and it was proposed that increased intake of vitamin C could boost collagen production and strengthen cells even more.

When Pauling and Cameron published their first edition, some of the ideas regarding hyaluronidase and collagenase were speculative. Pauling and Cameron were also relying on their collective scientific expertise to develop a model for vitamin C’s interactions with these enzymes. Pauling was not shy about making informed inferences to explain scientific phenomena, and in the case of vitamin C and these two enzymes, his thinking appears to have been correct. Since the publication of the first edition of Cancer and Vitamin C, two different research teams have published articles (in 2001, 2004, 2010, and 2011) which found evidence that vitamin C does in fact help to inhibit hyaluronidase.

More recent research has also suggested that high levels of vitamin C generate hydrogen peroxide. While it is not clear what the exact mechanism is that causes this, it is known that hydrogen peroxide can lead to a type of cell death that turns out to be useful in the cancer fight. Most healthy cells are not impacted by hydrogen peroxide because of the presence of an enzyme, catalase, that neutralizes its impact. Cancer cells, on the other hand, are not equipped with catalase; or if they are, the amount is negligible. So it is now well-established that hydrogen peroxide can kill cancer cells, but getting sufficient quantities of hydrogen peroxide to cancer cells inside the body has proven challenging. By administering large doses of vitamin C, it is hoped that clinicians may someday be able to provide targeted hydrogen peroxide therapy to patients who could benefit from it.


While Pauling and Cameron were able to provide data-based connections between vitamin C and its ability to fight cancer, their book also includes more anecdotal ideas that support their argument. One such observation was that patients who were given vitamin C for cancer treatment tended to experience less severe side effects from chemotherapeutics than those who did not take vitamin C. Although it was hard to quantify, Pauling and Cameron noted several instances where bed-ridden patients under Cameron’s care would take vitamin C and soon be capable of moving about. Cameron also observed that patients who stopped taking vitamin C often saw their symptoms rapidly return.

More notably, several of Cameron’s patients who were given vitamin C were found to go into remission. Because of ethical concerns related to placebo trials, Cameron and Pauling did not have any controls to support their claims. However, many of the patients took no treatment other than vitamin C, and Cameron, who had been a practicing physician for many years prior to beginning work on vitamin C therapy, understood that remissions for many of these cancers was not at all common.

To further support the notion that there was something special about vitamin C, Pauling and Cameron also observed that healthy people could not tolerate as much supplemental vitamin C as could those suffering from cancer. That is to say, healthy patients could take only so much vitamin C before they began to experience side effects, such as diarrhea, than was the case with cancer patients. This anecdote suggested to the authors that cancer patients needed a large amount of vitamin C – all of it was, in effect, being used, and as such there were no negative side effects. In fact, the appropriate dosage was often determined by giving a patient as much as they could tolerate before experiencing side effects.


Pauling and Cameron knew that vitamin C helped fight cancer. They saw that their patients were getting better and, from a molecular viewpoint, the mechanisms involved made sense, even if the data wasn’t in hand to prove everything. But there was more to support vitamin C as a model substance for treating cancer, and that had to do with its connection to scurvy, which we will explore in our next post.

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