More than 400 scientists will hear this week how a long term study into the links between diet and cancer is already saving lives.
A study of the food habits of 25,000 people is under way
About 25,000 volunteers in Norfolk have been keeping diaries of what they ate for the past 13 years.
Data is collected for the European Prospective Investigation of Cancer.
Researcher Prof Kay-tee Khaw said: "This is a big study with a lot more data so we can define conclusively the relationships between cancer and diet."
The study, which involves a total of more than 500,000 people across Europe, has already revealed the close link between eating red meat and the risks of developing cancer.
But results also showed that this effect could be counteracted by a high fibre diet.
She said that dieticians are now much more certain about what causes certain types of cancer because the study has "been able to confirm what people used to only suspect".
Looking for trends
This week she will tell the British Association Science Festival at the University of East Anglia that her team was now trying to find out what role fats may play in cancer.
"Some of it may be beneficial, some of it may increase the risk, we want to be much more clear about what fats are good for us and what fats are bad for us."
Norfolk was chosen for a major part of the European study because people tend to move to the county and stay.
The results of the food diaries are analysed by researchers at Addenbrooke's Hospital in Cambridge and those taking part undergo regular medical check ups.
Prof Khaw said: "What we're looking for is trends, we're not trying to find the people who eat well, we're trying to get a cross section of people's eating habits.
"So we have some diaries where people are eating fish and chips more than they should but we also have people who eat their five portions a day of fruit and vegetables."