The potential links between cancer risk and the foods we eat have generated a mass of media headlines in recent years. But for all the data linking certain foods with a reduced risk of cancer, there is very little good evidence to suggest an effect of diet in those already with the disease.
Speaking to NutraIngredients at the recent Vitafoods Europe show in Geneva, Professor Robert Thomas said that while public health efforts to encourage people to change their diet and lifestyle were a good idea, actually achieving these goals can be difficult.
"It's actually easier to change their lifestyle if that have had the fear of a diagnosis of cancer. It's what is called a teachable moment," said Thomas, who is a consultant oncologist at Addenbrooke's and Bedford, Cambridge University Hospital.
"As an oncologist, I only see people with cancer," he added. "All my patients in the studies have already got a diagnosis of cancer."
Last year, Thomas and his team published a study that suggested supplementation with polyphenol-rich fruit and vegetable extracts could have a significant benefit for certain cancer patients.
"I treat men with prostate cancer, and up to 70% of them were going in to health food shops and buying supplement - most of which have no evidence at all, some of which might be harmful to them."
"So it became obvious that we need to do more research to find out which supplements are helpful and which aren't."
As a result, the oncologist and his colleagues assessed a mass of scientific data from clinical trials on supplements and dietary interventions in order to select the most promising for a new clinical trial.
From this scientific assessment, they identified four polyphenol rich foods that had a good amount of data to suggest some benefit may be possible. These were: pomegranate, green tea, broccoli, and turmeric.
"We then designed a study to try and prove that those foods, in a supplement format [known as pomi-t], will reduce the risk of prostate cancer progression," he said.
The researcher and clinical oncologist told us that the findings from the study showed a powerful clinical effect as well as a statistical effect.
"It wasn't just a difference in a blood test. It was actually a difference in their subsequent management."
Check out our full length video with Professor Thomas to find out more on this work, and his plans for further research. You can also access the full research paper, published open access in Nature's Prostate Cancer and Prostatic Disease, to find out further details of the trial.