Putting Science Between the Hype and Reality about Vitamin C and Cancer

Cancer has touched Dr Gabi Dachs’ life in many ways – as a family member, lecturer, PhD supervisor and leading cancer researcher.

“Too many people I love and care for have died of cancer or trodden the path of a long, hard cancer journey,” she says. “I’m trying to do good research to help cancer patients live longer and better with cancer,” she says as she focuses her investigations on Vitamin C and cancer survival.

“One day I want to give clinicians the information they need in order to advise patients on exactly how much Vitamin C they need to stay well, and potentially, help fight their cancer.”

Supported by the Cancer Research Trust NZ, Gabi, Research Associate Professor at the University of Otago Christchurch campus, is studying kidney cancer to try and understand whether saturating tumours with Vitamin C could disrupt the low oxygen environment where cancers can thrive.

“Blood vessels in tumours often do not carry enough oxygen and so tumours have pockets of low oxygen. These conditions increase activity of a molecular ‘master regulator’, called Hypoxia-Inducible Factor (HIF), and make cancers more aggressive,” she said. “Our studies have found that whenever Vitamin C levels are high, saturating a tumour, then HIF activity drops. We've gathered evidence in mice that increasing Vitamin C supply resulted in slowing of tumour growth.”

The team, buoyed by the latest funding grants from the Cancer Research Trust, is using state-of-the-art equipment to analyse and measure samples donated to the Christchurch Cancer Society Tissue Bank by patients with kidney cancer.

“We’re putting science between the hype and reality around Vitamin C. We want to understand why and how Vitamin C could work in cancer patients, and to do so we need to measure things in clinical samples,” Gabi says.

“There’s so much misinformation out there about food and supplements and mega-doses of Vitamin Cit’s hard to convince the research funders that the biochemistry is real, not just hand-waving, and that there may be an important link between Vitamin C and cancer survival.

“Cancer Research Trust saw the merit in our investigation to take it to the next stage. We’re very grateful to the Trust for also supporting the next generation of researchers through funding for our talented PhD students.”

Gabi says we can all help ourselves in the fight against cancer by eating more healthily.

“Vitamin C is very beneficial to all of us, not just the critically ill. So, do yourself a favour and eat a balanced, broad diet,” she says. “I love my Gold Kiwifruit, broccoli, peppers and citrus fruit – and I love waking up each day doing what I’m doing to help people live good lives by unlocking the secrets to fight cancer.”

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Dr Gabi Dachs, Research Associate Professor at the University of Otago

The Link Between Vitamin C and Cancer – the Studies

Funded by the Cancer Research Trust, the researchers investigated a molecular mechanism by which Vitamin C affects cancer cells. Previous studies had shown a link between high levels of Vitamin C tumour saturation and reduced levels of the molecular regulator, HIF, and markers of cancer aggression. In this study, the exact mechanism by which this happens was studied.

Gabi and her team specifically chose kidney cancer for this research. Kidney cancer has two main types, one of which has regulated levels of HIF, whereas the other has uncontrolled high levels of HIF, and these latter cancers are particularly aggressive.

The researchers predicted that the kidney cancer type with regulated HIF would show a link with Vitamin C, whereas the type with uncontrolled HIF activation would not show a link. Indeed, the results have shown that the prediction was true. These results will help guide clinicians when they provide advice on Vitamin C to patients with cancer.

What has become clear in measuring Vitamin C levels in different cancer types and many different patients, was that levels of Vitamin C inside tumours varied greatly. The Cancer Research Trust again stepped in to provide funding to investigate the reason for this variation.

This grant allows Gabi and her team to measure the cellular transporters that move Vitamin C from the circulation into cancer cells. For this, samples from patients with breast, bowel and kidney cancer will be studied.

“This knowledge will help us to understand why there are some cancer patients who appear to have improved survival and many who do not respond to Vitamin C treatment,” Gabi says.

You can listen to Gabi and her colleagues, Professor Margreet Vissers and Dr Anitra Carr, talk in detail about their studies on Vitamin C here:

Dr Gabi Dachs was awarded three grants from Cancer Research Trust of New Zealand totalling $264,277. She was awarded the Bruce Blue Award in 2008 to study the impact of obesity and insulin-resistance on response to chemotherapy in colorectal cancer. In 2009 she was again the recipient of the Bruce Blue Award, this time for a study into the chemotherapy response in an obese mouse model with colorectal cancer. Lastly, she was awarded a 2016 grant to look at the role of vitamin C transporters in cancers.
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