Vitamin C is an essential micronutrient, vital for health. We often think of upping our intake to boost our immune system or brighten our skin.
But could it potentially be a useful tool in the fight against cancer and sepsis?
A symposium in Auckland this week looks at just that.
Treatment for throat cancer left Michael Barnett with severe burns, but he firmly believes intravenous vitamin C sped up his recovery.
"You could almost sense the recovery in yourself, and very quickly you could see the recovery in my neck and in my mouth and throat."
But he says doctors were unsure.
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"When I went back to the clinic after a couple of months and they looked at me, I was very proud of the recovery, and they sort of looked at it - it was almost as if I'd gone to the dark side."
Dr Richard Medlicott, College of GPs' Medical Director, says the medical community is sceptical.
"We'll be sceptical about Vitamin C until there's really strong evidence," he said.
"There's some stuff which shows an improvement in patient wellbeing - but even those are small studies, so it's certainly not a miracle cure."
Vitamin C plays a vital role in keeping our bodies functioning. When we're sick, our levels drop, so we need a boost.
In many cases, that means a diet rich in Vitamin C or a supplement, but for a higher dose it could mean an infusion.
An increasing number of patients are coming to clinics for support during chemotherapy and pre- and post-surgery. Each infusion costs between $160 and $300, and takes around 90 minutes.
But there's a lack of solid evidence to prove it works, and in what doses. Vitamin C has been shown to benefit patients with sepsis - but for cancer patients, it's unclear.
Professor Margreet Vissers from Otago University says it could be beneficial.
"We think that some people could benefit, but we don't currently know who, or for what types of cancer."
Prof Vissers says more research is needed to find out.
"Our question is really, could it work? And if so, how would that work?" she said.
"We're carrying out studies into how Vitamin C works in cancer cells and how it would be benefit for cancer patients."
She says only when there's clear evidence could scientists and GPs recommend it as a complimentary treatment. Until then, it's at the patient's discretion.