Researchers at the University of Newcastle believe that changes to the way food is grown and produced have robbed it off its anti-cancer agents.
They suggest that changes to farming methods over the past 100 years may have contributed to the growth in bowel cancer rates.
Bowel cancer is the second-most common cancer in the UK and kills nearly 20,000 people every year. However, if it is diagnosed early it is easily treatable.
The researchers are working on a study which indicates that Aspirin may be effective in fighting bowel cancer.
Aspirin link
They are carrying out two trials on people with a predisposition to developing the disease. Initial results show that salicylates, the active ingredient in Aspirin, is proving effective.
However, salicylates used to be a common component of many plants and vegetables.
All green plants generate salicylates as part of a natural defence mechanism.
This means that when a leaf or other part of the plant is infected, it generates salicylates which in turn localises the infection and ensures that it does not affect the rest of the plant.
No 'infected plants'
The researchers believe that modern farming methods mean that plants with "infections" do not get through the food chain and, as a result, human levels of salicylates can be quite low.
This in turn, they suggest, could prevent the human body from properly fighting bowel cancer.
"Modern farming methods mean that we do not eat plants with black spots or infections. We are not offered them and we are never exposed to them," said John Burn, professor of human genetics at Newcastle University.
"There is, therefore, no salicylates in the modern diet. The food and environment of a million years ago or even a thousand years ago is very different.
GM to 'trick' plants
"Today's diet has drifted from the diet we might have adapted in those times to cope with disease," he said.
Professor Burn is heading up two clinical trials to see if the theory is correct. But he sees many possible uses for the information, not least through GM food.
"We could use GM techniques to trick a plant into thinking that it is infected.
"This would mean it would generate salicylates which would could then be consumed by humans and could, in theory, protect people against bowel cancer."
Professor Burn will present his findings to the International Congress of Dietetics on Sunday.