According to a team at Mount Sinai School of Medicine, certain cooking methods produce a compound that contributes to early insulin resistance and abdominal weight gain, which are risk factors for diabetes.
Foods can be cooked in three main ways: dry heat, moist (wet) heat, and microwave. Dry heat cooking means you surround the food with hot dry air, usually at temperatures of 300 degrees Fahrenheit or higher. Methods of dry heat cooking include sauteing, baking, grilling, roasting, broiling, and deep frying (oil is not water, thus this is considered a dry heat method).
Moist heat cooking involves the addition of moisture (water) and includes boiling, steaming, simmering, poaching, braising, and stewing. Of the three methods, dry heat cooking is the one associated with a risk of diabetes, and here's why.
The connection between cooking method and diabetes is the formation of advanced glycation endproducts (AGEs), compounds that are produced when foods are prepared using high dry heat. This includes not only foods prepared using the cooking methods already noted, but many processed foods as well, since they are made using high heat.
The term "glycation" means a glucose molecule attaches itself to a protein molecule or fatty acid molecule in an uncontrolled manner, which results in the formation of damaged protein structures that the body has difficulty eliminating. When you eat foods high in AGEs, these substances accumulate along with free radicals and lead to inflammation, a recipe for diabetes and other diseases.
A scientific team under the direction of Helen Vlassara, MD, professor and director of the Division of Experimental Diabetes and Aging, conducted experiments with generations of mice, some of whom were exposed to a type of AGE called methyl-glyoxal (MG). A control group of mice was fed a diet identical to that of the MG-exposed group except for the addition of the MG.
Over a period of four generations, the mice fed the MG-supplemented diet showed the following:
- They developed signs of diabetes, including early insulin resistance and increased body fat in the abdominal area.
- A significant deficiency of SIRT1, a factor that controls inflammation
- An increase in the metabolism of insulin and glucose
- Reduced activity of AGER1, a critical anti-AGE receptor that protects SIRT1 and fights insulin resistance
On the other hand, the mice who did not receive MG had high levels of SIRT1, AGER1, and no diabetes.
According to Vlassara, their findings "should inform how we understand and prevent the human epidemic of obesity and diabetes." Basically, this study shows how continued consumption of "seemingly innocuous substances common in human food, such as MG," can make individuals susceptible to diabetes and other diseases.
More specifically, the authors suggest new clinical recommendations from doctors "should now include a reduction in the amount of dry heat and processed foods in the diet."
Everyone can make a conscious effort to modify their cooking methods and to order food at restaurants that are prepared using more healthful cooking techniques. For example, instead of grilled or fried chicken or fish, these items should be prepared stewed or poached. Instead of French fries, prepare or order mashed potatoes; simmer your veggies in broth instead of deep frying or grilling them. In fact, in the case of fruits and vegetables, eat them raw when possible.
Since AGEs, including MGs, are also found in many processed foods, the authors' recommendations also include a reduction in these items as well. Instead, select whole, natural fruits and vegetables, beans, legumes, nuts, and whole grains that are prepared using wet cooking methods, such as lightly steamed for vegetables or boiled for beans and legumes.
Weijing C et al. Oral advanced glycation endproducts (AGEs) promote insulin resistance and diabetes by depleting the antioxidant defenses AGE receptor-1 and sirtuin 1. Proceedings of the National Academy of Sciences 2012 Aug 20. doi:10.1073/pnas.1205847109