Dietary Advanced Glycosylated End Products (AGEs)

Earlier this month, we discussed the effect Advanced Glycosylated End Products (AGEs) have on the eyes and the body.

As part of that discussion, we learned that AGEs form slowly at the relatively low temperatures found in our bodies and quickly at the higher temperatures we use to cook. Many, if not most of the foods we eat in our modern western diet are heat-processed (ie: cooked) in some way, for food safety reasons, and for flavour, colour, and aroma. This causes physical changes to our foods (like popping corn) as well as chemical changes (like the colour change in the whites of eggs).

The Maillard Browning Reaction is a chemical reaction that browns food and gives it a distinctive flavour. It was discovered over a hundred years ago by Louis-Camille Maillard, and it occurs when the oven is set somewhere around 280 to 330 degrees Fahrenheit (140 to 165 degrees Celsius). Although there are undoubtedly other reactions that produce AGEs in our foods, the Maillard browning reaction is the easiest to understand, so we’ll use it as our knowledge foundation in this blog.  

If you do much baking or cooking at all, you’ve probably already realized that most recipes call for a temperature high enough to ensure that the Maillard Browning Reaction occurs. The changes in flavour, colour, and aroma that occur during the Maillard browning reaction make our foods delicious, but they also indicate to the chef that the food is now done and safely cooked. But what if safely cooked isn’t as safe as we thought?

Knowing about the effects of AGEs on our health, led researchers to wonder what we can do to slow the process of AGEs accumulation in our bodies. And as evidence builds, nutritionists are beginning to move from wondering, to believing that AGEs in our diet may contribute to oxidative stress and inflammation in our bodies. Researchers will one day be able to tell us how much our dietary intake of AGEs affects the accumulation of AGEs in our body tissues, but for now we don’t know. We’re forced to more or less draw our own conclusions, but if you believe, as I do, that a low dietary intake of AGEs may reduce the amount of AGEs accumulating in the tissues of your body, then you will want to know how to prepare your foods in order to limit your dietary intake of AGEs.  

In a previous article, we learned that AGEs form when proteins and fats combine with sugars in a process called glycation or glycosylation. We also learned that the process of glycation occurs faster at higher temperatures. So it makes sense that foods made with lots of protein, fats, and sugars will end up with containing more dietary AGEs than other foods, especially if they’re cooked at a higher temperature. Which leads us to our first tip.  

Cook at a Lower Temperature

What temperature is low enough to limit or slow the process of glycation? Probably any temperature low enough to slow or limit the Maillard browning reaction.  So, somewhere less than 330 degrees Fahrenheit (165 degrees Celsius). You may be wondering, Why not less than 280 degrees Fahrenheit (140 degrees Celsius)?  Well you are right, that would be better, but cooking times increase at lower temperatures, so it’s partly a practical decision. When I bake in the oven, I set the temperature between 285 and 315 Fahrenheit, and never above 325 degrees. I watch closely for browning, and call it done sooner.

If you like the idea of cooking at even lower temperatures, you’ll love having a vegetable steamer and a slow cooker in your kitchen.  Since these cook foods just above the boiling point of water, which is  212 degrees Fahrenheit or 100 degrees Celsius, they never bring food to a temperature that produces Maillard browning.  

Check your Ingredients

Foods that combine protein, fat, and sugar will contain more dietary AGEs, especially if they are prepared at temperatures above 325 degrees Fahrenheit. Although high fat foods contain the highest AGE content, meats and animal-products (if you eat them) will likely contribute more to your total dietary intake of AGEs because western diets currently serve meats in larger servings than fats. In order from highest to lowest amount of AGE levels we have:

Cheeses (especially those with higher fat content such as Parmesan and American)

In fact, a paper in the American Journal of Clinical Nutrition found that people can directly reduce their risk of developing cataracts with diet. Those who eat less meat in their diet had fewer cataracts than those who ate a typical Canadian diet. Those who ate no red meat, but continued to eat fish and animal-products had an even lower risk for developing cataracts, but their risk was still higher than vegetarians and vegans who had the lowest risk. On the reverse end, smokers, who inhale many AGEs with every cigarette, have a much higher rate of cataracts and often just look older than their non-smoking peers. The good news for current smokers is that, in a paper published in the medical journal JAMA Ophthalmology, researchers found that quitting does help reduce your risk of cataracts. But, unfortunately, you’re risk will always be higher than someone who never smoked.

Consider Marinating

The Maillard browning reaction works better in an alkaline environment. It doesn’t work well in acidic environments. Marinating meats for one hour in vinegar or lemon juice will cut the dietary AGE content after cooking roughly in half.  

Avoid Dry Heat

The Maillard browning reaction, and many if not all the other reactions that produce AGEs work better in dry heat than in humidity. Think about how quickly things brown on the barbecue.  In the barbecue, the temperature is generally higher and certainly dryer. In order to limit the formation of AGEs in our foods, we can consider steaming, boiling, and other ways of preparing foods at lower temperatures without dry heat.

When it comes to reducing AGEs in your food, one of my favourite options is slow cooking. Slow cooking keeps temperatures low and the cooking atmosphere humid. This is a great combination for avoiding adverse AGE effects. You may also want to consider reducing how much meat and animal products you eat. But, in the end, how you wish to eat and what diet works for you is going to depend a lot on your individual priorities and needs. Many Canadians, for example, struggle with weight, so if you’ve only just found a diet that works for helping you control your weight, you may not want to fiddle with it. That’s completely understandable.

At Doig Optometry, we just want to share our knowledge and help Calgarians to make the best informed decisions for them. If you want to see whether AGEs are already beginning to have adverse effects on your eyes, blood vessels, and body in general, the Calgary eye doctors at Doig Optometry can help! Contact us today to learn how!

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