- British researchers drew conclusions after analysing diets of 1,800 men
- Eating five portions of fruit and veg a day also decreased risk by 24%
- Tomatoes are rich in lycopene, previously linked to good prostate health
- Researchers: Daily servings of selenium and calcium also reduce cancer risk
The scientists behind the new study say they have developed the first prostate cancer 'dietary index' to help prevent the disease, which is the second most common cancer in men worldwide.
Researchers from the Universities of Bristol, Cambridge and Oxford examined the diets and lifestyles of men - with and without the disease - aged between 50 and 69.
Tomatoes are rich in the compound lycopene, which has previously been linked to good prostate health
They found those who consumed more than 10 portions of tomatoes each week - such as tomato juice and baked beans - saw an 18 per cent reduction in risk.
Eating the recommended five servings of fruit or vegetables or more a day was also found to decrease risk by 24 per cent, compared to men who ate 2.5 servings or less.
And in the first work of its kind, they developed a list of the three vital dietary components - selenium, calcium and lycopene - said to lower the risk of developing prostate cancer.
Our findings suggest that tomatoes may be important in prostate cancer prevention,' said Vanessa Er, from the School of Social and Community Medicine at the University of Bristol.
'Men who ate more than 10 servings of tomato based products per week, compared to those who ate less, saw their chances of having prostate cancer development reduced by 18%.'
She added that it was best to try and get the dietary components such as lycopene and selenium from food rather than supplements.
'Even though we found tomatoes and tomato products did have this reduction in risk, we still advise men to have a variety of fruits and vegetables, stay healthy and active and maintain an ideal weight,' she said.
Rates of prostate cancer are higher in developed countries, with some experts believing this is linked to a Westernised diet and lifestyle.
To examine this, the researchers assessed the diets and lifestyles of 1,806 men aged between 50 and 69 with cancer, compared with 12,005 cancer-free men.
The data was taken over an eight year period, from 2001 to 2009.
The team examined previous research and dietary recommendations linked to prostate cancer and developed the 'dietary index' of selenium, calcium and lycopene rich foods.
Their work suggests men should aim for 10 or more portions of tomatoes each week, between 750mg and 1,200mg of calcium a day and between 105mcg to 200mcg of selenium daily.
The research was published in the medical journal Cancer Epidemiology, Biomarkers and Prevention. In Westernised diets, selenium is most commonly found in flour-based foods such as bread and pasta, while calcium is most found in dairy products such as milk and cheese.
The researchers are now calling for further research to develop additional dietary recommendations to help prevent prostate cancer.
'We have to be very careful about this research because we have found a link, it is not a proof of causation,' Miss Er added.
'Further studies need to be conducted to confirm our findings, especially through human trials.'