Summer is finally upon us. After weeks of rain and unpredictable weather, we are now able to enjoy those favorite summer activities. Swimming, biking, kayaking, …and oh, let’s not forget the barbecue. What a more perfect way to spend with family and friends than to be outdoors cooking on the grill. But make no mistakes, there are health issues to consider before you fire-up that grill.
It has been well established that cooking meat on the grill is dangerous for your health. Deadly, as a matter of fact. A high consumption of meat that has been cooked over an open flame or on grills that use hydrocarbons does indeed contribute to the onset of cancer. Studies have shown an increase in colon cancers in persons who eat food cooked in this way. Why is this, and what is the culprit?
Before I answer those questions, it’s important to understand the nature of cancer. Cancer is not a single disease. There is an enormous number of genes whose alteration will initiate cancer in a particular cell type. Processes within a normal cell are highly regulated. The highly ordered sequence of events in the life of a cell is called the cell cycle. Within this cycle, there are signals that tell cells when to grow, divide and die. If these signals are altered, the cell cycle becomes unregulated and cancer ensues.
Cancer starts with a mutation in DNA. The induction of the mutation varies depending on the carcinogen (radiation, chemical, biological or endogenous). Among the most common include DNA insertions or deletions, breaks, dimers, and the addition of adducts to a DNA strand. DNA replication proteins become confused by these changes and replicate the DNA strand erroneously. As a result, the protein coded by the mutated gene does not function normally, or the protein becomes silent or absent within the cell. Sometimes the cell recognizes this abnormality and the DNA is either repaired or the cell dies in the process known as apoptosis. Other times the cell escapes this fate and continues to divide and live longer than it ordinarily would because the protein(s) that once kept it in check are no longer functioning normally. The cell also loses its ability to adhere to other cells and migrates through the body (a process called metastasis).
The cancer causing chemical found in grilled foods is called benzo(a)pyrene (BaP). BaP is a polycyclic aromatic hydrocarbon that forms as a result of incomplete combustion of organic molecules. Simply put, the burning of any organic substance, such as cigarettes, wood, gasoline, meat, may create BaP. When meat is cooked on a grill, molecules normally found in meat can be transformed into BaP. BaP can also be formed from the fuel used by the grill and be carried to the meat with the smoke. As a result, BaP covers grilled meat. Then you eat it. A marshmallow roasted over an open flame also contains BaP.
BaP is not as harmful to humans as its metabolites. BaP enters the blood stream, and once it enters a cell it is converted to other compounds by specific enzymes. The resulting metabolites bind to DNA, forming large adducts that confuse the proteins responsible for DNA replication. Most of the time these adducts are removed through DNA repair mechanisms, but not always. If enough of the adducts remain, the protein coded by the mutated DNA strands does not function normally, or it is simply not transcribed at all. There will then be a cascade of events that triggers the onset of carcinogenesis.
The effects of BaP is cumulative. That is, the more BaP metabolites that bind to DNA, the more likely your chances of getting cancer. It is simply a matter of numbers: it’s more efficient for a DNA repair protein to remove a single adduct from DNA than it is for it to remove a dozen. What this means is that if you absolutely love char grilled food, than eat it. But do so in moderation.