- Dr Amy Loughman & Madeline West
Delicious foods and AGEing...
Updated: Feb 24, 2021
You may have heard about AGEs - yet another fancy term for something that is apparently bad for our health. AGEs are allegedly another type of nasty found in those not-so-good-for-us treat foods.
Declared by some as the key to age-related health conditions, AGEs - Advanced Glycation End products - have been linked to heart disease, insulin resistance, and neurodegenerative diseases including Parkinson’s and Alzheimer’s.
Wait, what are AGEs?
Scientifically speaking, AGEs are a heterogenous, complex group of compounds that are generated in the body and present in some foods. And what does this actually mean? Basically, that there are a lot of different types of AGE’s and that our body can make them itself, but they can also be ingested when we eat certain foods.
In the body, AGEs are slowly produced over time during the normal process of ageing. In foods, AGEs are commonly found in two places:
in cooked foods, particularly foods that have been toasted, baked or fried and have developed that delicious brown colour – think fries or croissants – yum!
animal products that are high in fat and protein.
When we cook foods, they undergo a browning process, technically known as “the Maillard Reaction” (or glycation – the ‘G’ in AGEs!). This happens when sugars are combined with certain amino acids or fats and is the most common reason we find AGEs in our cooked foods. Hence, when animal products that naturally contain AGEs are cooked at high temperatures or aged, such as steaks, sausages and bacon, the AGEs are especially high.
Although we have identified two key sources of AGEs – 1) produced by the body and 2) eaten in foods – we still don’t know if one source is more detrimental that the other. For the remainder of this article we will focus on the evidence around diet-derived AGEs.
What does the research say?
Even though we know that foods can be a source of AGEs, there are still large question marks around what effect these diet-derived AGEs may have on health. In fact, there isn’t even a consensus on whether consumption of a meal high in AGEs will increase bodily levels of AGEs (measured in urine and blood). This is possibly due to the different nature of different AGEs and how much is absorbed vs. excreted, different methods for measuring AGEs, as well as there likely still being some AGEs we don’t know about yet! So, as you can see there are many still unknowns.
In terms of relevant health outcomes, researchers have begun investigating AGE-consumption in some diseases including diabetes, cardiovascular disease, and chronic kidney disease. In these three diseases, low-AGE diets have been suggested to reduce fasting insulin levels, reduce total and LDL cholesterol - cardiovascular disease risk factors, and improve endothelial function, in type 2 diabetes, CVD and chronic kidney disease, respectively. However, larger and more robust studies are needed to confirm these findings.
A large body of evidence in the area of AGE consumption and health has investigated inflammation and oxidative stress. As inflammation is implicated in many chronic health conditions, such as those listed above, this is an important area to be explored. Current evidence has suggested that a low-AGE diet may improve markers of inflammation and oxidative stress in healthy people and reduce oxidative stress in diabetic patients. Similarly, another study has suggested a high-AGE diet may perpetuate chronic disease through inflammation and oxidative stress. However, many of these trials have been of short durations (some as little as 6 weeks!) meaning that the long-term benefits of a low (or high) AGE diet are still unclear. This is something many scientists have acknowledged themselves in their papers;
“due to lack of high-quality randomized trials, more research is needed.” Clarke et al., 2016
“There is currently insufficient evidence to recommend dietary AGE restriction for the alleviation of [inflammation] in healthy individuals and patients with diabetes or renal failure.” Kellow & Coughlan, 2015
“Existing studies are controversial, inconclusive or of low quality so that further high-quality studies from independent research groups are needed to clarify the role of dietary AGEs.” Nowotny et al., 2018
And what about AGEs and ageing?
Inflammation and oxidative stress are considered important risk factors for age-related diseases such as cardiovascular disease, diabetes and even Alzheimer’s Disease (AD). So, given the evidence suggesting a relationship between AGEs and inflammation, it’s been proposed that reducing AGEs through a low-AGE diet may help promote healthy ageing – makes sense, right?
One of the most common diseases we associate with ageing, and one that we are yet to cure is AD. It has been suggested that having a high load of AGEs may contribute to this, and other, age-related neurodegenerative disease. This is not only due to the inflammation caused by AGEs, but these AGEs may also accumulate in the brain. One study looking at the brains of humans who had died with AD, found them to have 3-times more AGEs than the brains of those who did not die with AD. Other studies have found levels of specific AGEs in blood and cerebrospinal fluid at higher levels in individuals with AD compared to healthy people of the same age. The mechanisms thought to be involved with these processes are to do with inflammation and oxidative stress. However, exact mechanisms are still under investigation.
The final word
Even though you will find articles from years ago stating that a low-AGE diet is key for good health, these articles seem to be fuelled by a lot more hype than evidence. Basically, the jury is still out on the actual health effects of AGE-consumption with more high-quality studies needed before we can start to make any recommendations.
But, for the time being, if we think about the fact that foods with the lowest amount of AGEs are unprocessed fruits and vegetables (the foods we should be eating the most of anyway), and those higher in AGEs being highly processed foods, by maintaining a balanced diet in-line with the Australian dietary guidelines, you’ll be looking after your health and won’t need to think too hard about how many AGEs you’re eating.
Madeline West is an Associate Nutritionist and research assistant currently working with Dr Amy Loughman at the Food & Mood Centre on the Healthy Brain Project (Microbiome substudy).