A couple of hamburgers a week could increase the chances of getting prostate cancer by 40 per cent, according to new research.
Scientists say cooking meat at a high temperatures creates cancer causing chemicals that damage DNA.
A study of almost 2,000 men found prostate cancer cases rose dramatically in those who often ate meat cooked in a pan, with red meat being particularly dangerous.
Chemical carcinogens are formed when meat is cooked at a high temperature
Professor Mariana Stern, of the University of Southern California, said: 'We found men who ate more than 1.5 servings of pan-fried red meat per week increased their risk of advanced prostate cancer by 30 percent.
'In addition, men who ate more than 2.5 servings of red meat cooked at high temperatures were 40 percent more likely to have advanced prostate cancer.'
The carcinogens at the centre of the scare are known as HCAs (heterocyclic amines) and PAHs (polycyclic aromatic hydrocarbons).
HCAs form when protein is cooked at high temperatures for a long time, while PAHs occur when fat from the meat drips onto an open flame creating smoke that deposits the chemicals on the meat.
There is strong experimental evidence that HCAs and PAHs contribute to certain cancers, including prostate cancer.
When considering specific types of red meats hamburgers, but not steak, were linked to an increased risk of prostate cancer, especially among Hispanic men.
Prof Stern, whose research was published in the online journal Carcinogenisis, said: 'We speculate these findings are a result of different levels of carcinogen accumulation found in hamburgers, given that they can attain higher internal and external temperatures faster than steak.'
The participants, more than 1,000 of whom had advanced prostate cancer, answered questionnaires about their red meat and poultry consumption. They were also asked to photograph their cooking methods and how charred their meat was.
The researchers said the study, published online in the journal Carcinogenesis, provides important new evidence on how red meat and its cooking practices may increase the risk for prostate cancer.
Previous studies have emphasised an association between diets high in red meat and risk of prostate cancer, but proof is limited.
But attention to cooking methods shows the disease may be a result of potent chemical carcinogens formed when meat is cooked at a high temperature.
The researchers also found the men who ate baked poultry had a lower risk of prostate cancer, but those who pan fried it had a higher risk.
Prof Stern said pan-frying, regardless of meat type, consistently led to an increased risk of prostate cancer. The same pattern was evident in her previous research which found fish cooked at high temperatures, particularly pan-fried, increased the risk of prostate cancer.
The researchers do not know why pan-frying poses a higher risk for prostate cancer, but they suspect it is due to the formation of the DNA-damaging HCAs during the cooking of red meat and poultry.
Added Prof Stern: 'The observations from this study alone are not enough to make any health recommendations but given the few modifiable risk factors known for prostate cancer, the understanding of dietary factors and cooking methods are of high public health relevance.'
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