Consuming foods that have been browned at high temperatures can produce some unwanted chemicals that are increasingly being linked to metabolic disease risk.

When food is cooked there is always some degree of chemical change taking place. Many of these changes are positive because they add to the flavour and appearance of food and can even improve the bioavailability of some nutrients.

However there is one chemical change that has scientists looking more closely for potential links with disease.

Advanced glycation end-products (AGEs) are a class of food chemicals that arise naturally when food is heated to the point of browning or charring.

The Maillard reaction, at it’s called, is caused by a reaction between sugars and amino acids in proteins. It’s what gives roasted food its distinctive flavour and aroma and bread its brown crust.

AGEs are not entirely benign chemicals and accumulation of them in the body can promote oxidative stress and inflammation. Researchers are now also linking AGEs to part of the development of insulin resistance and type 2 diabetes.

Type 2 diabetes is strongly characterised by a decline in insulin sensitivity as a person becomes more ‘resistant’ to their own insulin so the findings of this short-term study are noteworthy.

Adding more depth to the field, researchers studied how switching to a diet low in AGEs could affect insulin sensitivity in healthy, overweight volunteers.

Twenty adults followed a defined diet for two weeks that was either high or low in AGEs but similar in total energy and nutrient make up. After a four week break from the low or high AGE diet they then switched to the alternative diet.

The key outcome of the study was how well the body responded to insulin. On the low AGE diet, sensitivity went up, while on the high AGE diet, it either stayed the same or declined slightly.

Implications

The research into AGEs and inflammatory diseases such as diabetes is still at an early stage, but as the research from both animal and human studies continues to grow, it is telling a similar narrative.

A ‘low AGE diet’ includes plenty of fruits and vegetables and minimally processed foods. This diet also means eating less overly processed foods, especially baked and fried foods. When cooking, opt for shorter heating times, use lower temperatures and a high moisture content and avoid over browning or charring food.

Last Reviewed: 19/09/2019

© Norman Swan Medical Communications.



References

de Courten B et al. Diet low in advanced glycation end products increases insulin sensitivity in healthy overweight individuals: a double-blind, randomized, crossover trial. American Journal of Clinical Nutrition Epub online March 30, 2016. doi: 10.3945/ajcn.115.125427.