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To follow up on my report on the dangers of cooking plant-based foods at high temperatures, the research on cooking meats at high temperatures is of even greater concern. Again, we are finding new studies confirming an ancient Ayurvedic premise that all foods should be cooked gently on a low heat.
The National Cancer Institute at the National Institutes of Health reported on the cancer risks from cooking meat at high temperatures. (1) When meat from the muscle of beef, pork, fish and poultry are cooked using high temperatures, cancer-causing heterocyclic amines (HCAs) and polycyclic hydrocarbons (PAHs) are formed. HCAs and PAHs have been found to be mutagenic – that is, they cause changes in DNA that may increase the risk of cancer. (1)
The report suggests that the cooking time, the heat used, the type of meat and method of cooking will determine the amount of HCAs and PAHs formed. Meats cooked at high temperatures, especially above 300 degrees Fahrenheit (as in grilling or pan frying), or that are cooked for a long time (well-done) tend to form more HCAs. For example, well-done, grilled, or barbecued chicken and steak all have high concentrations of HCAs. (1)
The National Cancer Institute report suggested that high levels of HCAs and PAHs can cause cancer in animals, but made the point that the effect in humans was unclear. Since the 2010 National Cancer Institute study, more recent 2012 studies have confirmed the link between a diet of meats cooked at high temperatures and cancer in humans. (2,3)
HCAs are formed when amino acids – the building blocks of proteins, and sugars, and creatine – a substance found in muscle, react at high temperatures. A similar process also takes place in plant-based foods creating dangerous acrylamides. 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 the smoking of meats. (1) PAHs are also found in charred foods, as well as in cigarette smoke and deadly car exhaust fumes. (1)
The National Institutes of Health suggest the following to avoid dangerous levels of HCAs and PAHs: (1)
- HCA and PAH formation can be reduced by avoiding direct exposure of meat to an open flame or a hot metal surface.
- Reduce the cooking time to avoid eating well-done meat.
- Turning meat over while on a high heat source can substantially reduce HCA formation.
- Remove charred portions of meat and refrain from using gravy made from meat drippings.
According to Ayurveda, we should cook all foods over a low flame and never eat burned or charred foods. Boiling meats in a stew is a traditional method that minimizes the high temperature risks of burning or overheating the food.