A Texas university study now shows that eating not only red meat, but white meat in large quantities could also increase the risk of developing cancer. The reasons point to a combination of cooking methods as well as genetic predisposition.
A team at the University of Texas MD Anderson Cancer Center in Houston compared diets of 659 patients diagnosed with renal cell carcinoma (RCC) to 699 similar people without cancer. The study looked at what kinds of meat people ate, how they cooked it, besides their genetic makeup.
Those who ate the most grilled meat -- red or white -- had higher risk of kidney cancer. However, it has not always been clear why eating more meat elevates cancer risk, explained Stephanie Melkonian, PhD, postdoctoral fellow, Epidemiology and lead author of the study.
Looking for an explanation, they narrowed on the cooking method where high temperatures produce carcinogenic substances. The team looked for cancer causing mutagens, two in particular -- 2-amino-1-methyl-6-phenyl-imidazo (4,5-b) pyridine (PhIP for short ) and amino 3,8-dimethylimidazo (4,5-f) quinoxaline (MeIQx for short). They identified a 54% increased risk associated with PhIP intake and a nearly twofold increase associated with MeIQx intake.
"We found elevated RCC risk associated with both meat intake and meat-cooking mutagens, suggesting independent effect of meat-cooking mutagens on RCC risk," said Xifeng Wu, MD and PhD, professor, Epidemiology and senior author of the study.
Besides the high intake of meat, those with two genetic mutations were most affected by the grilled meat risk. A high meat intake was particularly harmful for a subgroup of the population carrying variations of the gene ITPR2.
This gene has even before been associated with kidney cancer and obesity risk, the results point to exposure to meat-cooking mutagens. Future experiments will probe the link between mutagen intake and genetic susceptibility.
While advising people to consume meat in moderation, the researchers advise a well-balanced diet, complete with fruits and vegetables. The high risk group also ate fewer fruits and vegetables than people who did not have cancer.
Kidney cancer is among the 10 most common cancers in both men and women, according to the American Cancer Society which notes rising incidence of kidney cancer since the 1990s. The team suggest that increased meat intake may be the reason.
It was just a few weeks ago that the International Agency for Research on Cancer (IARC) came out with a report giving evidence that high intake of processed meat causes cancer while red meat may also probably cause cancer. The report was contested for its definition of red and processed meat.