The risk of cancer could be cut by 12%, just by adopting a couple of elements of the Mediterranean diet, say scientists.
Using more olive oil alone cut the risk by 9%, found a study of 26 000 Greek people.
The British Journal of Cancer reports that higher amounts of fruits, vegetables, cereals and less red meat, are also included in the diet.
And for men vulnerable to prostate cancer, a separate stucy found that adding broccoli to meals might help them cut the risk.
The Mediterranean diet came under scrutiny after researchers noticed lower rates of illnesses like heart disease, in countries such as Spain and Greece.
People living there generally ate more vegetables and fish, less red meat, cooked in olive oil and drank moderate amounts of alcohol, researchers noticed.
The latest study is one of the largest yet to look at the potential impact on cancer of the various parts of this diet.
Thousands of Greek people of various ages have been persuaded, by researchers from Harvard University, to record their food intake over an eight-year-period.
Using a scoring system, their adherence to the Mediterranean diet was ranked, and the group with the worst score compared with those who followed a couple of aspects of the diet, and those who followed it the most closely.
A 9% reduction in risk is the biggest effect they found. It was achieved simply by eating more “unsaturated” fats, like olive oil.
But the risk of cancer can be cut by 12% by only two changes : eating less red meat, and more peas, beans and lentils.
“Adjusting one’s overall dietary habits towards the traditional Mediterranean pattern had an important effect”, said Dr Dimitrios Trichopoulos, who led the study.
The importance of a healthy balanced diet has been highlighted by the research, said Sara Hiom, from Cancer Research UK.
“It shows there are a number of things you can do, and there is no one ‘superfood’ that can stop you developing the disease.”
The Institute of Food Research in Norwich made the other study, also suggesting that food had the power to prevent cancer.
The effects of adding 400 grams of broccoli or peas a week to the diet of men at risk of prostate cancer have been compared by scientists. In the case of broccoli, they found differences in the activity of genes in the prostate, that other studies have linked to cancer.
Their findings raised the possibility that broccoli, or other “cruciferous” vegetables, like cauliflower and Brussels sprouts, could help prevent or at least slow down the disease, particularly if the man had a particular gene variant : GSTM1.
“Eating two or three portions of cruciferous vegetables per week, and maybe a few more if you lack the GSTM1 gene – should be encouraged”, said Professor Richard Mithen, who led the research, published in the Public Library of Science journal.
It was the first time that, in a properly controlled clinical trial, broccoli had been shown to change the expression of specific genes in the prostate gland, said Professor Karol Sikora, medical director of CancerPartnersUK.
“Although the observation period was too short and the numbers too small to show that the incidence of cancer actually fell, it is the first clear demonstration that broccoli and presumably other cruciferous vegetables may well reduce cancer risk.”