Vitamin C and Cancer: Rays of Hope



[Part 4 of 4]

Ridiculed by the medical profession for two decades, the tide began to shift for vitamin C and cancer starting in 1992. That year, the New York Academy of Sciences voted to discuss high-dose vitamins and nutrients at its annual meeting, devoting several sessions to the antioxidant properties of vitamin C and its potential value at higher-than-dietary amounts in preventing lung, stomach, colon, and rectal cancers.

Oddly, throughout the proceedings, one prominent name had been missing from the conversation, a point noted by a professor from Alabama who finally spoke up, saying,

For three days I have been listening to talks about the value of large intakes of vitamin C and other natural substances, and I have not heard a single mention of the name Linus Pauling. Has not the time come when we should admit that Linus Pauling was right all along?

Since 1996 the Linus Pauling Institute, relocated from California, has continued work on cancer from it’s new home at Oregon State University. Basing these contemporary orthomolecular studies on the hard sciences of cellular biology, molecular biology, and organic chemistry, the Institute continues to explore the cutting edge of health and nutrition research.

Working under Dr. Balz Frei, the current director of the Institute, as well as former LPI principal investigator Dr. Roderick Dashwood (now director of the Center for Epigenetics and Disease Prevention at Texas A&M University), OSU student Matt Kaiser has spent time analyzing the benefits of vitamin C treatment for colorectal cancer, which remains the third leading cause of cancer related deaths in the United States. The Pauling Blog has interviewed Kaiser in the past, and we met with him again recently to gain a better sense of trends in the community of researchers interested in vitamin C and cancer.


One primary question that begs further exploration is, why didn’t earlier studies find evidence of the value of vitamin C?

As it turns out, the problem appears to have been primarily located in the way that vitamin C was being administered. The 1979 Mayo studies to which Pauling so strongly objected had assumed that, since vitamin C was filtered out of the body after a certain point of blood saturation, higher doses need not be examined. This assumption – that excess vitamin C could not be absorbed and was simply excreted in the urine – was one of the most basic issues of contention that Pauling was never able to get past with the medical community. However, it now appears that the assumption applies only if vitamin C is taken as an oral supplement, a breakthrough that was first identified by Mark Levine, a Senior Investigator at the National Institutes of Health.

Matt Kaiser explains

Mark Levine realized in the 1990s that the way drugs are distributed and function in the body [pharmacokinetics] can drastically change the amount of vitamin C entering blood plasma. Eating vitamin C you can only get about 250 micromolar [a measure of vitamin C, or ascorbate— to use its chemical name— that can be concentrated in the blood stream]. With intravenous injection, the levels are much larger: 200 times. One millimole is a thousand micromoles, so 30 millimolar [of ascorbate in blood plasma] is a huge difference!

At these high pharmacological— or even super physiological— doses, Levine found that cancer cell populations dropped significantly. To understand why, it is important to know a bit about how cancer works.

Human DNA can wrap up tight (heterochromatin) or unwind into a loose, more open configuration (euchromatin). When it is wrapped up tight, the genetic information on the DNA cannot be expressed. This is because transcription, which is the process by which a cell reads and expresses the genetic code, requires access to DNA.

There are very specific times when DNA should be wrapped tight to maintain optimum health, and other times when one’s body needs to be able to use the instructions for cellular function that are contained in DNA. When DNA needs to be unwound, molecules called histone acetyltransferases (HATs) help to unwind it. When it needs to be wound up tight, the process is aided by histone deacetylases (HDACs).

HDAC overexpression is a hallmark of cancer cells, and hyperactive HDAC cells lead to messy, knotted DNA winding. This biological circumstance hinders the cell from reading important instructions found in DNA, which in turn prevents the production of important tumor suppressor proteins. At the same time, it leaves certain sections of the genetic code open that should not be expressed.

“Basically,” says Kaiser, “You remove the break from the car, and then you also step on the gas. And that’s cancer.”


Matthew Kaiser.

The prevailing theory of how vitamin C acts on tumors is that it functions as a “prodrug,” meaning that it stimulates biochemical processes that allow something else to kill the cancer cell, rather than acting on it directly. In this case, the active agent is hydrogen peroxide, which is produced in saturated tissues by excess vitamin C. “Vitamin C acts as the Trojan horse that allows hydrogen peroxide to enter the tumor site,” Kaiser explains. “You can’t inject it straight in; your body will react too strongly. Hydrogen peroxide is a reactive oxygen species…it tears cells apart.”

However, since working on the project, Kaiser has found that this consensus on how vitamin C fights cancer isn’t necessarily the whole story. Pharmacological levels of ascorbate appear to selectively reduce the presence of proteins that regulate reactive oxygen species, like hydrogen peroxide, in cancerous cells. Some of these same proteins also happen to promote cell growth, which is not something that one would wish for cancer cells to do. In addition to producing hydrogen peroxide, ascorbate actually inhibits the runaway HDAC production that makes cancer cells so dangerous.

“What makes it really hard, really complicated,” Kaiser laments, “is that this might not work the same way for different types of cancer cells in different locations. There’s still so much to understand about how vitamin C is having this protective effect…That’s what’s lacking and that’s why we need studies like this.”


And indeed, more studies are coming. In keeping with it’s mission to extend and promote what it calls “healthspan,” LPI hosts a bi-annual Diet and Optimum Health Conference, bringing together experts from around the world to talk about topics in orthomolecular medicine, among other fields. This year the conference, which was held at OSU in September, featured several speakers discussing vitamin C and cancer. One of them was Dr. Mark Levine, the NIH scientist who first showed the value of intravenous ascorbate.

Margreet Vissers and Anita Carr, of the University of Otago in New Zealand, also described their own advances on the subject. Vissers found in her studies that levels of 50 micromolar ascorbate in blood plasma (average dietary levels are between 40 and 80) had little to no protective effect against cancer. Doubling the amount to 100 micromolar, however, boosted a patient to the lowest level of the protective range. It would seem, then, that Pauling was right to suggest that mega doses might be important for optimum health.

Vissers also explained that, in animal models, ascorbate injected intravenously will peak after about twenty hours in both healthy tissue and in tumors. However, unlike the healthy tissue, tumor tissues hold onto the vitamin C and do not return to a natural baseline. This detail is important because it allows high doses of ascorbate to build up in tumor tissue, and these doses disproportionately kill cancer cells instead of healthy tissues for reasons that are still not fully understood.

Conversely, the dangers of using vitamin C, even in high intravenous doses, appear to be small. While some people harbor an enzymatic deficiency that can cause a severe negative reaction, most individuals simply cannot overdose on vitamin C. Even in the blood plasma, vitamin C usually reaches a saturation point and is filtered from the body.

At the LPI conference, Dr. Carr pointed out that this form of treatment also dramatically improves the quality of life of cancer patients as compared to chemotherapy. For one, vitamin C treatments involve significantly less pain, mental and physical fatigue, nausea and insomnia. As of March 2015, three clinical trials involving pharmacological levels of ascorbate have been conducted, all of them showing that it is well tolerated by patients and reduces chemotherapy-related toxicity.

Additionally, vitamin C at high doses is known to aid cognitive function, and these positive benefits work together to aid in social satisfaction for the patient. As Pauling pointed out in the 1970s, it is not only the disease that the doctor should be concerned about treating, but the patient as well.


Pauling in 1989 – an extraordinary life. Photo by Paolo M. Sutter.

So is Linus Pauling vindicated when it comes to vitamin C and cancer? The answer is complicated.

On the one hand, it would appear that vitamin C can serve as an important preventative and treatment for cancer. However, the method that Pauling advocated— taking large supplemental doses orally— is pretty clearly not an effective form of application. Rather, contemporary research indicates that the levels of ascorbate that are required to slow or stop tumor growth are far greater than that which can be achieved naturally by ingesting vitamin C; they can be accomplished only by intravenous injections of ascorbate. Furthermore, it is likely that this form of treatment will not replace, but instead will augment, existing protocols including chemotherapy.

But the broader trend is optimistic and, one might argue, validating. And with the Linus Pauling Institute and many others around the world continuing to investigate the potential for vitamin C and other nutrients to help people live longer and feel better, exciting new studies on optimum diet and effective treatments for diseases like cancer would appear to be on the near horizon.