Can certain cooking techniques or browning of foods speed up the rate at which you age? Stephanie Osfield has the story.
Imagine if toasters only had a ‘super light’ setting or your Sunday lunch involved stewing the meat, not baking it to a mouth-watering crisp. Your toast and weekend roast would lose much of their palate appeal if they weren’t golden and crisp.
The process of browning food happens when, in high temperatures, sugars react with the proteins in foods. This creates compounds that not only change the colour, texture and smell of food, but also alter the flavour, making it more mouth-watering.
Unfortunately, as food browns during cooking, less pleasant chemicals are also formed.
How browning leads to AGEing
The unpleasant chemicals that are released when food is browned are aptly named AGEs (Advanced Glycation End-products).
Emerging evidence indicates eating too many of these AGEs could fast-track the ageing process in your body.
“Recent research suggests that excessive consumption of AGEs may be linked to conditions like cancer, Alzheimer's, diabetes and narrowing of the arteries,” says Professor Merlin Thomas, an expert in AGEs, Senior Research Fellow at the Baker IDI Heart and Diabetes Institute in Melbourne and co-author of Fast Living Slow Ageing (Mileage Media, 2009).
Speeding up your AGEing clock
Just as the sun ages our skin from the outside, these chemicals age our bodies from the inside. The main impact comes from AGEs travelling around our bodies, causing inflammation, loss of flexibility and stiffening of tissues. This occurs everywhere from the collagen in skin and the inside of arteries to the myelin protecting nerves in the brain.
“There is a strong relationship between the levels of AGEs in our diet and the level found in our blood,” Prof Thomas says.
He also explains the damage caused by AGEs is greater in people with conditions like diabetes, where their high blood sugar levels lead to more AGEs being produced.
Not surprisingly, fast food is another culprit. Research by Josephine Forbes at the University of Queensland, found that, “even short-term consumption of processed foods high in AGEs can have detrimental effects on insulin sensitivity, which may hasten development of type 2 diabetes.”
“Some studies have shown that eating a low-AGEs diet significantly prolongs the lifespan of mice - even when the mice eat as much as they like,” says Prof Thomas. But, he points out, “the equivalent research in humans is yet to be done.”
Foods that speed up AGEing
The process of browning food, particularly at high temperatures (above 250ºC) produces AGES, potentially damaging chemicals. So, that same process that makes these foods golden-brown and so moreish may also promote ageing from within.
roasted, charred or fried meat
roasted chicken skin
very dark toast
Meat is one of the major sources of AGEs. “In light of this it is helpful to reconsider the way we cook and eat meat,” says Prof Thomas.
“The higher the temperature in cooking, the more AGEs you make.”
So to reduce AGEs, we need to minimise or avoid techniques like chargrilling, roasting or baking, searing and frying.
These dry and high-temperature cooking methods also cook the fat back into the meat, increasing your fat intake.
“By contrast, cooking methods like steaming, partially render the fat from meat (leaving it in your pan rather than on your plate), so the meat is lower in AGEs as well as kilojoules and cholesterol,” says Prof Thomas.
So, what about the good old Aussie BBQ?
Sadly, the news is not good. The high temperature of the flame combined with the smoke while cooking meat, fish or poultry, increases not just AGEs but also problematic chemicals called HCAs (heterocyclic amines) which have been linked to an increased risk of bowel cancer in animal studies.
This is why Cancer Council Australia recommends we avoid burning our meat - and that goes for chargrilled sausages on the barbie. So barbecued food is better served up occasionally.
What’s the best way to cook?
Altering your cooking methods is the most effective method for reducing AGE levels. The best ways to cook are to:
Lower the temperature
Cooking at lower temperatures, below 180ºC, reduces AGE formation. “For example, scrambled eggs prepared in an open pan over medium-low heat have about one half the AGEs of eggs prepared in the same way but over high heat,” says Prof Thomas.
Add more moisture
“A chicken breast fried in oil has five times the AGEs as the same chicken breast when poached,” Prof Thomas explains. This is because moisture reduces AGE formation. So try making a weekly meal plan to include techniques like boiling, poaching, stewing, steaming, or using a slow cooker.
Fighting the AGE fire
For a quick anti-AGEing cooking method, just add water. Adding moisture to food through cooking techniques, such as stewing, steaming or boiling, can help cut the AGE content of food. Steam ovens are now available as an alternative to traditional dry ovens, and are growing in popularity in Europe.
Other good news, a number of cooking ingredients can further reduce AGE levels. For example, studies show when cooking meat, lemon juice or vinegar used in a marinade cut AGE formation by over half ñ so add one or the other or both to your favourite marinades.
Just as the natural and added sugars in foods contribute to the formation of AGEs during cooking, sugars in your diet can cause the production of AGEs inside your body, says Gerald Muench, Professor of Pharmacology at the University of Western Sydney. He explains not all sugars are as destructive as others.
“Glucose [part of the starch found in pasta, rice, potatoes and bread] has the least reactivity so makes lower levels of AGEs,” Prof Muench explains.
“Other sugars such as fructose, found in foods like [simple table] sugar, can be more reactive in big quantities, increasing AGE levels.
“This is another good reason to minimise intake of high sugar foods with low nutritional value, such as soft drinks or doughnuts or chocolate,” Prof Muench says.
Plant-derived foods, such as soy, tea, fruit and vegies are also helpful in defending against AGEs. They contain antioxidants that act like a SWAT team, scavenging for AGEs in your body, making them less harmful.
“Including more of these foods in your diet is a good idea” says Prof Thomas.
The take-home message? When it comes to AGEs, according to Prof Thomas: “You are as old as what you eat.”
Lowering your AGE levels through diet
Some types of foods have a lower impact on your body, causing less AGEs (the potentially damaging chemicals released when food browns) than others. So consider what you eat, as well as how you cook it.
Where possible choose unprocessed foods. These have the lowest AGE levels. Fresh vegetables and fruits are healthy choices that defend against AGEs.
Cut back on saturated fats. All low-fat products create fewer AGEs when they are cooked than their higher fat alternatives. “Cooking with butter generates more AGEs than cooking with margarine or oil,” adds Prof Thomas, an AGEs expert from Baker IDI Heart and Diabetes Institute.
Reduce packaged food intake. Many processed foods such as crisps, muesli bars, biscuits and roasted nuts are higher in AGEs than fresh, unprocessed foods.
Choose healthy whole grains. A lightly-toasted sourdough rye produces less AGEs than a darkly-toasted white bread. Wholegrains in muffins or cakes also help lower AGE content. Toasted muesli has higher AGEs than cereal like porridge made from whole oats.
Did you know?
A diet low in chargrilled foods may significantly prolong lifespan.
Cooking at lower temperatures below 180ºC, reduces AGE formation.
Cut it out: Minimise or avoid techniques like chargrilling, roasting, searing and frying.