What are AGEs and why should I care? AGEs are advanced glycation end products. The more of them we have, the older our body is. Glycation is the addition of sugar to protein. When sugar on protein reacts it welds molecules together, making tissues stiffer. Our joints get stiffer and we get less flexible. Our heart gets stiffer and does not pump as well. Our blood vessels get stiffer and our blood pressure goes up. Our bones get more fragile and break more easily. Our liver and kidneys cannot process molecules as well, so they start to fail. AGEs are involved in cataracts and may contribute to aging of the brain.
Collagen is the major structural support molecule in our body and is the main molecule that gets welded by glycation. The process involves one collagen molecule crosslinking to another collagen molecule. This prevents the molecules sliding past each other normally.
Another molecule that is crosslinked by glycation is elastin which gives elasticity to the tissues. It allows, for example, the skin of young people to snap back into place when pulled. In older folks with deteriorated elastin, skin sits as a fold when pulled and slowly moves back into place.
How AGEs Form
AGEs form in 2 main ways. One is by the action of enzymes and the other is by direct chemical reaction between a reducing sugar and an amino acid of a protein. The second method occurs more frequently in diabetics than non-diabetics and may contribute to a diabetic's accelerated biologic aging.
The second method also occurs in food. There is evidence that when we eat food that is high in AGEs, our tissues develop more crosslinks that result in our accelerated aging even if we are not diabetic.
AGEs Are Absorbed And Harm Our Health
Previously researchers thought that AGEs in food were not absorbed, so dietary AGEs were not investigated much. Now researchers know that about 30% of AGEs in the food we eat is absorbed and gets into our blood stream. And there is evidence that those with a higher level of AGEs in the blood stream die earlier and die more from cardiovascular disease (1).
Should we be concerned about AGEs in food? Only in the broadest sense. You should try to reduce the amount of food with the highest amount of AGEs, and increase the amount of food with the lowest amount. You would be doing this already if you are on a high potassium foods diet. But to pick foods based only on their AGEs score would be a mistake since the field is still in its early phase.
Foods That Are High In AGEs
How do we know what foods are high in AGEs? Until the past few years there was only limited knowledge of the amount of AGEs in foods. It was known that cooking at high temperatures resulted in AGEs in food. They are a result of the Maillard reaction. So the advice that was given was to avoid “browned” food, such as fried meat, bread crust, and other foods with a “browned” appearance. This is still a fairly good general rule.
But some tests have been developed to determine the level of some of the AGEs in food. They have shown that the previous approach was misleading about some foods. We will discuss some of the findings in the next post.
Research is still quite early and the recently developed tables may turn out to be as problematic as the antioxidant tables that were recently made unavailable by the USDA. The most extensive table relies on the level of CML and another smaller table on the level of MG. Both tables can be found in this article (2).
There are a great many AGEs, and each AGE will probably have a different effect on the body when consumed. But the tables are the best information we have at present, and can provide a preliminary tentative guide.
The tables should only be a general guide. It may be quite a while before there are good enough tables based on extensive enough knowledge to provide strong recommendations. The strongest nutritional recommendations at present are those about vitamin and mineral minimums, saturated fat, sodium and high potassium foods. There are several other areas with strong recommendations, but the areas have less known about them, such as fructose. And then there are areas that have promising initial studies, but are too incomplete in knowledge to have anything except tentative recommendations, such as antioxidants and AGEs.
For tables with potassium and macronutrient values of foods, click this link and scroll to the article with the table of interest.