Vitamin C, cancer and infection – Expert Q&A

Researchers will meet in Auckland this week to discuss the potential role of Vitamin C in cancer and infection.

The Vitamin C Symposium includes New Zealand and international speakers, and a public session on Saturday afternoon.

The SMC prepared a Q&A with one of the symposium organisers.

Professor Margreet Vissers, Centre for Free Radical Research, University of Otago.

Why don’t humans produce their own Vitamin C? What implications does this have for human health and Vitamin C’s importance in our bodies and diets?

“Most animals make vitamin C in their liver and make it according to need – more when they’re sick and less when they are well. Humans lost the ability to make vitamin C a long time ago and share this inability with monkeys and other primates, guinea pigs, fruit bats, some fish and a few birds. Interestingly, these species all eat high vitamin C diets.

“For us as humans, this means that we are completely dependent on getting vitamin C from our food. If we don’t take in as much as our bodies are turning over, our body levels will drop. Low vitamin C status compromises many of the functions of vitamin C, and this is now realised to be more important than we previously thought as many new functions supporting immunity, gene expression and stress responses are discovered. The health implications cover almost all aspects of our lives.”

How has Vitamin C been used to help treat or prevent infection or sepsis? How is it proposed to work and what is the evidence for its effectiveness?

“Until recently it was thought that the recommended daily intake of vitamin C was sufficient for healthy living for everyone, every day. But the evidence is now clear that the body consumes more vitamin C when infected and sick, requiring increased intake to restore depleted levels. New international pharmacokinetic studies show that when intensive care (ICU) patients are given enough vitamin C to restore healthy levels, clinical outcomes are dramatically improved, death rates are markedly reduced, and time spent in ICU is shorter.”

Vitamin C in cancer treatment has attracted headlines, and scepticism, over recent years; what is the history of investigations into its use?

“The use of vitamin C for cancer was first pioneered in the 1970s by the double Nobel Laureate Linus Pauling and Ewen Cameron, with reports of efficacy when given at high doses by intravenous routes. However, these studies were regarded with scepticism, largely due to there not being a plausible mechanism to explain how vitamin C might be working. Despite this, many people have continued to use vitamin C for cancer (this is allowed as the vitamin is not a drug), with numerous anecdotal accounts of benefit. However, the lack of rigorous scientific and medical studies has meant that this topic has remained controversial.”

Where does the evidence currently stand on Vitamin C as a cancer treatment? How is it proposed to work and what is the evidence for its effectiveness?

“The use of high-dose vitamin C infusions to treat cancer remains controversial due to a lack of solid evidence over its efficacy, with little reliable information available for patients and doctors due to an absence of good clinical studies. Medical science requires rigorous and objective evidence, and in the absence of basic scientific knowledge about the functions of vitamin C, this evidence has been lacking.

“New discoveries have identified a number of plausible options for vitamin C activity in cancer and the necessary clinical studies are now beginning. But this is now changing. We are progressively filling that knowledge and evidence vacuum and it’s now becoming possible for us to have a more rational and informed discussion about appropriate clinical use. We are progressively gathering the evidence that will allow us to identify which patients might benefit from vitamin C treatment, and what conditions are required for their treatment.”

What recommendations are there for patients who might be considering Vitamin C as a cancer treatment?

“The clinical trials that will enable doctors to give informed advice to patients regarding the value of vitamin C for cancer are not yet complete. Therefore at this time, patients should consult carefully with their doctors for any plans around their treatment options. We simply do not have all the information to be able to make clinical decisions yet.”

Are there any other uses of Vitamin C that are being investigated?

“Renewed understanding of the importance of vitamin C for many diverse biological functions is opening doors to new areas of research that impact on metabolic health, cognition, wound healing, skin health and energy/vitality.”

Prof. Vissers studies vitamin C’s role in cancer, immunity and optimal health.