She said it remained a "controversial" issue due to a lack of solid evidence and further research was needed in New Zealand before it was sufficient enough for hospital use.
"For a while now there has been little reliable information available for patients and doctors due to an absence of good clinical studies. But that is now changing," Vissers said.
A clinical trial in Christchurch - led by Vissers and associate professor Anitra Carr - kick started local research about a year ago and was already showing promising results.
"We are still recruiting people and it's still in the early stages, but we hope it will give us a better understanding of how Vitamin C impacts cancer and infectious diseases such as pneumonia and sepsis," Vissers said.
She stressed life-changing benefits from topping up vitamin C levels didn't work for everyone.
The clinical trial would enable doctors to give informed advice to patients regarding the value of vitamin C for cancer, Vissers said.
"At this time, patients should consult carefully with their doctors for any plans around their treatment options," Vissers said.
Top oncologist and medical director of Cancer Society New Zealand Chris Jackson said
he supported further research into vitamin C potentially shrinking cancer and prolonging life because it was currently lacking.
"There hasn't yet been a randomised clinical trial to clearly show this impact on cancer," Jackson said.
For some cancers, it is suggested that vitamin C is potentially helpful and other studies have shown it can be harmful - there have been patients who have developed kidney problems as a result, Jackson said.
"We know that many of our patients use alternative therapies alongside their medical treatment and that's an important part of their treatment - oncologists support this use but always want them to disclose and discuss," Jackson said.
International experts on the topic are gathering in Auckland tomorrow for a two-day symposium to discuss the latest research.
Minister of Health David Clark was invited to attend but could not make it.
Vissers said she was meeting with the minister next month to discuss this research.
Leading US critical care physician and researcher Dr Michael Hooper - who will be speaking tomorrow - said trials he'd undertaken on a small number of severely infected patients had a significant improvement in survival with vitamin C.
"With minimal to no toxicity, the use of vitamin C for severe infections could well revolutionise the care of severely infected patients worldwide.
"Large trials are now under way which will settle the debate over whether or not severely-infected patients should be treated with intravenous vitamin C as standard care," Hooper said.
A public session at Auckland University of Technology on St Paul St will be held as part of the symposium on Saturday from 2pm to 4.30pm.
The history on vitamin C:
High-dose vitamin C has been studied as a treatment for patients with cancer since the 1970s. A Scottish surgeon named Ewan Cameron worked with Nobel Prize-winning chemist Linus Pauling to study the possible benefits of vitamin C therapy in clinical trials of cancer patients in the late 1970s and early 1980s.
In the past 10 years, high-dose intravenous vitamin C has been frequently given to patients as a treatment for infections, fatigue, and cancers, including breast cancer in the US.
