Oregano protects grilled meats from bacteria and cancer-causing compounds

Adding oil of oregano to meat before grilling could reduce the formation of potentially cancer-causing compounds by up to 78 percent, University of Arizona researchers have found. It also helps inactivate harmful E. coli O157:H7 in the meat.

Research conducted by U.A. microbiologist Sadhana Ravishankar has shown that a compound in oregano reduces the formation of heterocyclic amines, the potentially cancer-causing culprits that can form in grilled meat.

"We are preventing the formation of potentially carcinogenic compounds in the grilled meat itself, so people can eat safer grilled meat," said Ravishankar, an assistant professor in the U.A.'s department of veterinary science and microbiology in the College of Agriculture and Life Sciences.

Heterocyclic amines form in grilled, charbroiled or fried meat in two essential steps. First, a raw juicy hamburger is slapped on the grill. As the meat heats up, amino acids and glucose in the meat react with each other to create molecules known as intermediates. Next, these intermediates react with creatinine, a molecule that is present in muscle. The result is heterocyclic amines.

Once the nice and crispy hamburger is eaten, the heterocyclic amines potentially could lead to cell malfunction. Several epidemiological studies have shown a possible correlation between the consumption of well-done meats and different types of cancers in humans.

So maybe people can live without that extra crispy texture on their meat. Unfortunately that strategy has a pitfall too: There are established standards for cooking ground beef in order to eliminate harmful E. coli bacteria in the vast majority of commercial meat. Restaurants often recommend well-done meat to minimize the potential for foodborne illness.

"We added the active ingredient of oregano oil, called carvacrol, to the meat. Then we grilled the meat, and we were able to reduce the formation of these compounds," said Ravishankar. "Carvacrol has anti-oxidative properties, so we are thinking that it binds to or reacts with some of the intermediates and prevents them from forming the heterocyclic amines. The mechanism is not clear yet."

Carvacrol also has antimicrobial properties that inactivate E. coli: a membrane-active compound, it breaks the chain of fatty acids that makes up the outer membrane of an E. coli cell, causing the cell to leak its contents.

Her study was published in the Journal of Agricultural and Food Chemistry.

Dr. Grout’s comment:

Ravishankar's research has shown for the first time a way to simultaneously inactivate harmful E. coli and reduce the formation of potentially carcinogenic compounds in grilled meat.

It is important not to confuse oil of oregano with the oregano that is used as a spice for cooking. The common oregano spice is typically Origanum Marjoram, while oregano oil is derived from Origanum Vulgare. Oil of oregano is a natural substance extracted from wild oregano plants, and two key compounds found in it are carvacrol and thymol. Quality oregano oil should sell for between $10 to $16 per 15 ml at health food stores.

The ancient Greeks were one of the first people to recognize oregano oil for its health benefits and medicinal qualities. It is known to be a potent antiviral, antibacterial, antifungal, and antiparasitic oil that can reduce pain and inflammation and effectively fight off infections.