When sugars are cooked with proteins or fat at temperatures over 120°C (~248°F) or at lower temperatures for longer cooking times, a molecule known as advanced glycation end products (AGE) is formed. This AGE is known as exogenous gylcation, as opposed to endogenous glycation, which is created inside the body by metabolic processes.
These orally absorbed reactive glycation products are also known as “glycotoxins” or dietary AGE products (dAGE). The dAGE products are known to contribute to increased oxidant stress and inflammation, and may result in diabetes and cardiovascular disease.
An article that appeared in the Annals of the New York Academy of Sciences in 2006 by Helen Vlassara entitled: Advanced glycation in health and disease: role of the modern environment, demonstrated that there is evidence from animal studies that point to AGE restriction as an effective means for extending median life span, similar to that previously shown by marked caloric restriction. The authors conclusion is quite definitive:
“We conclude that excessive AGE consumption, in the current dietary/social structure, represents an independent factor for inappropriate oxidant stress responses, which may promote the premature expression of complex diseases associated with adult life, such as diabetes and cardiovascular disease.”
Most, if not all, processed foods has some measure of dAGE. Food manufactures will add sugar to their products to enhance the browning effect, thus contributing to the addition of dAGE’s. Any food that is caramelized and browned contains dAGE’s.
The Journal of the Academy of Nutrition and Dietetics published a very interesting Table listing the advanced glycation end product (AGE) content of 549 foods, based on carboxymethyllysine content.
The method of cooking is also crucial to the production of exogenous AGE’s. Specifically, grilling, broiling, searing, roasting, and frying produce and accelerate new AGE formation in food.
Animal-derived foods that are high in fat and protein have been shown to have higher AGE products and especially after cooking these animal products using the methods described above. Carbohydrate-rich foods such as vegetables, fruits, whole grains, contain relatively few AGEs, even after cooking.
In the August 2004 Journal of the American Dietary Association an article entitled: Advanced glycoxidation end products in commonly consumed foods, listed some interesting results regarding the dAGE content of certain food and the highest dAGE for each cooking method:
“Foods of the fat group showed the highest amount of AGE content with a mean of 100+/-19 kU/g. High values were also observed for the meat and meat-substitute group, 43+/-7 kU/g. The carbohydrate group contained the lowest values of AGEs, 3.4+/-1.8 kU/g. The amount of AGEs present in all food categories was related to cooking temperature, length of cooking time, and presence of moisture. Broiling (225 degrees C) and frying (177 degrees C) resulted in the highest levels of AGEs, followed by roasting (177 degrees C) and boiling (100 degrees C).”