Today I was at the American Society of Nephrology Meetings in San Diego.  Instead of enjoying the magnificent weather, I spent the day indoors listening to an excellent series of talks on the aging kidney. A talk by Professor Helen Valassara from Mount Sinai School of Medicine in New York particularly caught my attention.

Her career has focused on the effects of high glucose levels on the tissues in the body. These glucose levels are changed into age related glucose endproducts (AGEs). This process is similar to what is seen when food is heated and turns brown. Unfortunately these AGEs are highly toxic to the body. This is thought to be one of the reasons why persons with diabetes mellitus develop eye, kidney and nerve damage as well as accelerated atherosclerosis.

Dr Valassara  began to wonder if eating food with high concentrations of AGEs would also be toxic to humans. As she pointed out nutrients are thermally(heat)-sensitive. Heating food leads to an increase in AGEs. The higher the heat and the longer the heating process the more AGEs are produced. So a boiled potato has only 174 AGEs whereas a fried potato has 2838 AGes. A fresh apple has 127 AGEs while a baked apple has 445 AGEs. Microwaving produces less AGEs than most other forms of cooking.  

She then decided to feed low AGE diets to mice and compare them to AGE-rich diets. She found that the low AGE diet increased lifespan in mice. She then found that the low AGE diet  protected against diabetes, vascular disease, kidney disease and the development of obesity. Her group then showed that in humans AGEs from food are absorbed and increase inflammation. A low AGE diet reduced inflammation.

The BOTTOM LINE according to Dr Valssara is “Don’t grill; Don’t fry.  Cook with plenty of water. Decrease the time and temperature of cooking.” This fits with the high fruit and vegetable  and Meditteranean  diets, both of which are associated with a longer lifespan.