When food is cooked, a number of chemical changes occur. Many of these are positive as they add to the flavour and appearance of food and even the bioavailability of some nutrients. But there is one chemical change that has scientists looking more closely for potential links with disease. These food chemicals, called advanced glycation end-products (AGEs), arise naturally when food is heated to the point of browning or charring. It’s called the Maillard reaction and 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 even linking AGEs to the development of insulin resistance and type 2 diabetes. Furthermore, researchers are now exploring if their inflammatory action could also affect dementia development.

Mice raised on a diet high in AGEs were much more likely to develop symptoms consistent with dementia compared to mice fed a low AGE diet. Mice on the high AGE diet showed increased amounts of amyloid beta proteins in their brains. These proteins are the sticky substances that can form plaques in the brains of people with Alzheimer's disease.

Taking the research outside the mice cage, the researchers monitored the blood levels of AGEs in 93 adults aged over 60 for a period of nine months. Even over this short time, those people who had more AGEs in their blood experienced greater cognitive decline as well as reduced insulin sensitivity compared to those with low AGE levels.

Implications

The research into AGE and inflammatory diseases is still at an early stage, but the findings from both animal and human studies are certainly encouraging scientists to dig deeper. The good news here is that a low AGE diet is very much in line with healthy eating guidelines: higher amounts of fruits and vegetables and minimally processed foods, and less overly processed foods, especially baked and fried foods. When cooking, opt for shorter heating times, use lower temperatures and high moisture content and avoid over browning or charring food. Slow cooking fits well with a low AGE diet.

Last Reviewed: 28/02/2019

© Norman Swan Medical Communications.



References

Cai W et al. Oral glycotoxins are a modifiable cause of dementia and the metabolic syndrome in mice and humans. Proceedings of the National Academy of Sciences 2015;111:4940-4945.