Grilled or barbecued meat may cause kidney cancer
A new study claims that meat, whether pan-fried, grilled or barbecued when cooked at high temperatures or over an open flame, may increase the risk of kidney cancer.
Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are chemicals formed when muscle meat, including beef, pork, fish, or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame. In laboratory experiments, HCAs and PAHs have been found to be mutagenic—that is, they cause changes in DNA that may increase the risk of cancer.
HCAs and PAHs become capable of damaging DNA only after they are metabolized by specific enzymes in the body, a process called ‘bioactivation.’ Studies have found that the activity of these enzymes, which can differ among people, may be relevant to cancer risks associated with exposure to these compounds.
HCAs are formed when amino acids (the building blocks of proteins), sugars, and creatine (a substance found in muscle) react at high temperatures.
PAHs are formed when fat and juices from meat grilled directly over an open fire drip onto the fire, causing flames. These flames contain PAHs that then adhere to the surface of the meat. PAHs can also be formed during other food preparation processes, such as smoking of meats.
HCAs are not found in significant amounts in foods other than meat cooked at high temperatures. PAHs can be found in other charred foods, as well as in cigarette smoke and car exhaust fumes.
The study illustrates how diet and genetics may interact to impact cancer risk. The researchers said that incidence of renal cell carcinoma (RCC), the most common form of kidney cancer in adults, has been increasing in the US and other developed nations. Researchers suspected that factors related to a western lifestyle -such as a diet high in meats, processed foods, and starches may play an important role in this trend.
To investigate, a team led by Xifeng Wu, of The University of Texas MD Anderson Cancer Centre in Houston, studied the dietary intake and genetic risk factors of 659 patients newly diagnosed with RCC and 699 healthy controls. Researchers found that kidney cancer patients consumed more red and white meat compared with cancer-free individuals.
Population studies have not established a definitive link between HCA and PAH exposure from cooked meats and cancer in humans. One difficulty with conducting such studies is that it can be difficult to determine the exact level of HCA and/or PAH exposure a person gets from cooked meats. Although dietary questionnaires can provide good estimates, they may not capture all the detail about cooking techniques that is necessary to determine HCA and PAH exposure levels. In addition, individual variation in the activity of enzymes that metabolize HCAs and PAHs may result in exposure differences, even among people who take in the same amount of these compounds. Also, people may have been exposed to PAHs from other environmental sources, such as pollution and tobacco smoke.
Numerous epidemiologic studies have used detailed questionnaires to examine participants’ meat consumption and meat cooking methods to estimate HCA and PAH exposures and researchers have found that high consumption of well-done, fried, or barbecued meats was associated with increased risks of colorectal, pancreatic, and prostate cancer.
