THE approach to cancer which seeks to identify "villains" in the human body, and kill or remove them, is wrong in many instances, according to a leading authority on nutrition.
This method fails to sufficiently appreciate the role of "preventive foods" such as fruit and vegetables, the chairman of the European Cancer Prevention Organisation, Dr Michael Hill, said yesterday. He was speaking in Dublin at a conference on cancer and nutrition hosted by Royal Irish Academy national committee for nutritional sciences.
Many regarded cancer as a microbial disease, which was undoubtedly the explanation for tobacco-related or asbestos-induced cancers where defences were overwhelmed by a massive carcinogenic load, he said. But it did not explain other forms of cancer.
For diet-related cancers of the stomach, breast and colon, a better approach might be to regard them as nutrient deficiency diseases. "We are not doing very well in trying to identify villains. So I would contend these cancers are due to a lack of preventive factors. Where we are going wrong is not having enough of them in our diet," Dr Hill said.
There were indications that an imbalanced diet was as significant a cause of cancer as tobacco in Ireland, he told the conference. Studies had repeatedly shown that a third of cancers could be prevented by a change in diet, though some cancers we re linked to genetic inheritance.
A distinction, nonetheless, had to be made between cancers associated with a poor diet, and others associated with a rich "Western diet". Yet a more balanced dietary strategy could prevent both forms.
Meat had been identified as a "risk factor", but a definitive Japanese study had shown it was only when the consumption of fruit and vegetables was low that meat could pose a cancer threat.
His advice was to "enjoy your food". People should avoid being overweight if possible, eat plenty of fruit, vegetables and whole grain cereals, and fish. Plenty of fruit and vegetables meant at least five portions a day, weighing 500g in total. There were numerous antioxidants and vitamins in fruit and vegetables, including some 4,000 flavonoids which could protect against cancer. It was not clear yet which individual ones were best. Because of this, people needed to consume the whole food rather than supplements.
Dr Sheila Bingham of the Medical Research Council nutrition unit in Cambridge said people were often taking far in excess of requirements.
"It is far better to increase consumption of fruit and vegetables. The evidence so far relates to food, especially vegetables, rather than supplements of vitamins, minerals or purified extracts. Attempts to alter risk with supplements have so far not been successful and are not recommended for the general population," she said.
The benefit of limited but regular consumption of red wine in reducing heart disease deaths had been known for years, but its ability to prevent cancer due to the presence of natural compounds know as flavonols was now emerging, said Dr Alan Crozier of the University of Glasgow.
He has established that Cabernet Sauvignon, Merlot and Pinot Noir from Chilean vineyards contain much higher levels of flavonols than red wines made from the same species of grape in other countries. This might be because warm, dry climates enable the grapes to ripen fully.
