AGEs: a very apposite acronym

If the UPF conversation is about the degree of processing, then the AGE conversation is about its biochemical cost.

AGEs, a type of gerontotoxin (from the Greek geros, meaning “old age”), are recognised as significant risk factors that contribute to “inflamm-ageing”, a chronic low-grade inflammation that accelerates the ageing process.

It would be hard to find a more apposite acronym.

How are AGEs formed?

As nutrition becomes an increasingly popular “therapeutic” strategy to promote health, the effects of cooking are under increasing scrutiny. Many foods nowadays are exposed to processes that enhance flavour and palatability. But those processes are also responsible for the formation of harmful compounds: AGEs.

AGEs are a consequence of the Maillard reaction, named after French scientist Louis-Camille Maillard. We actually look for this effect when cooking: colour, caramelisation, savoury aroma, depth of flavour. And it begins innocently enough. When a reducing sugar meets an amino acid, they undergo chemical reactions that alter their structure. Initially, browning and flavour compounds form, but eventually — especially under high heat and low moisture — AGEs are produced.

Minced beef. browning in a pan

This happens on an industrial scale in the pet food industry. Commercial pet foods, especially kibble and canned varieties, are often processed at extremely high temperatures to ensure safety, extend shelf life and enhance palatability. But those same methods inevitably produce Maillard Reaction Products (MRPs) and, further down the chain, the oxidatively active molecules we know as AGEs.

Inflamm-ageing: AGEs and links to health

Dietary AGEs are already a concern in human nutrition because of their implication in inflammatory and degenerative diseases. Clinical studies have now shown links in both humans and animals to various diseases, including diabetes, cardiovascular disease and neurodegeneration[1].

One recent human study noted: “For our own health, it is necessary to be aware of the toxic risks of AGEs, understand the importance of healthy diet and habits, and minimize the risk of diabetes, cardiovascular complications, and other glycation-related diseases”[2].

So, if our dogs eat industrially processed diets for much of their lives, what does that mean for them? Isn’t it time to ask what these processes leave in their wake and what impact this might be having on – or what compounds it might be leaving in – our dogs’ bodies?

Canine research

Although canine research into dietary AGEs and their health impacts lags behind human research, there is a growing body of evidence pointing to the biological cost of long-term exposure and how MRPs and AGEs interact with the immune system in animals. Research to quantify AGEs and related Maillard products in commercial diets[3] has confirmed the presence of various MRPs at measurable levels.

Studies into the long-term effects of MRP consumption show some important impacts, for example:

  • the reaction chemically “locks up” critical amino acids like lysine, reducing bioavailability and lowering nutritional quality[4];
  • the more processed food dogs and cats are fed, the greater the ratio of AGEs detected in their urine[5];
  • the average daily intake of a certain AGE called hydroxymethylfurfural (HMF) can be 122 times higher for dogs than for humans per unit of body weight, because HMF is a by-product of the Maillard reaction during the high-heat processing of foods like dry kibble and canned pet food[6].

The effects are not theoretical: AGE accumulation has been observed in dogs with atherosclerosis[7], diabetes[8], cataracts[9] and cognitive dysfunction[10]. While these are associations, not proof of dietary causality, the direction of travel is clear.

What we do know is that MRPs and AGEs aren’t just inert by-products, harmless leftovers from processing.

Processing

Black and white image of kibble

As we learn more about how processing forms MRPs and AGEs, it is becoming clear that food preparation methods are just as important as the ingredients themselves.

A recent analysis of a wide range of processed foods and treats noted that the Maillard reaction can lead to the loss of essential amino acids and the formation of AGEs that may negatively affect animal health[11]. In fact, one study in 2021 pointed out that “Emerging research in dietary advanced glycation end products will impact the future of pet food industry.”[12]

Four years later, I’m wondering how.

But for now, the implications are straightforward: gentler cooking methods inherently produce fewer AGEs than high-temperature, low-moisture industrial processes. Steaming, poaching and slow cooking do not drive the reaction chain as aggressively as extrusion or retorting (canning). Combining kibble with fresh food may, even unintentionally, dilute exposure.

Even small shifts in cooking method, variety and processing level may make a difference over time.

Cook smarter: Use lower heat and longer moist cooking to inhibit AGE formation.

Choose wisely: Opt for less-processed foods and be mindful of foods with high heat treatment.

Support the gut: Consider adding probiotic-rich foods or fibres that promote beneficial microbes to counteract potential negative effects.

 

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References:

[1] Zhang, Y., Zhang, Z., Tu, C., Chen, X., & He, R. (2025). Advanced Glycation End Products in Disease Development and Potential Interventions. Antioxidants, 14(4), 492. https://doi.org/10.3390/antiox14040492
[2] Peng, Huan & Gao, Yuqi & Zeng, Chenye & Hua, Rui & Guo, Yannan & Wang, Yida & Wang, Zhao. (2024). Effects of Maillard reaction and its product AGEs on aging and age-related diseases. Food Science and Human Wellness. 13. 1118-1134. 10.26599/FSHW.2022.9250094.
[3] van Rooijen C, Bosch G, van der Poel AF, Wierenga PA, Alexander L, Hendriks WH. Quantitation of Maillard reaction products in commercially available pet foods. J Agric Food Chem. 2014 Sep 3;62(35):8883-91. doi: 10.1021/jf502064h. Epub 2014 Aug 20. PMID: 25088431.
[4] Teodorowicz M, Hendriks WH, Wichers HJ, Savelkoul HFJ. Immunomodulation by Processed Animal Feed: The Role of Maillard Reaction Products and Advanced Glycation End-Products (AGEs). Front Immunol. 2018 Sep 13; 9:2088. doi: 10.3389/fimmu.2018.02088. PMID: 30271411; PMCID: PMC6146089.
[5] Palaseweenun P, Hagen-Plantinga EA, Schonewille JT, Koop G, Butre C, Jonathan M, Wierenga PA, Hendriks WH. Urinary excretion of advanced glycation end products in dogs and cats. J Anim Physiol Anim Nutr (Berl). 2021 Jan;105(1):149-156. doi: 10.1111/jpn.13347. Epub 2020 Apr 11. PMID: 32279406; PMCID: PMC7818435.
[6] van Rooijen, C., Maillard reaction products in pet foods, Animal Nutrition, Food Chemistry, WIAS, doi: 10.18174/360655
[7] Chiers K, Vandenberge V, Ducatelle R. Accumulation of advanced glycation end products in canine atherosclerosis. J Comp Pathol. 2010 Jul;143(1):65-9. doi: 10.1016/j.jcpa.2009.12.006. Epub 2010 Jan 29. PMID: 20116070.
[8] Comazzi S, Bertazzolo W, Bonfanti U, Spagnolo V, Sartorelli P. Advanced glycation end products and sorbitol in blood from differently compensated diabetic dogs. Res Vet Sci. 2008 Jun;84(3):341-6. doi: 10.1016/j.rvsc.2007.05.013. Epub 2007 Jul 13. PMID: 17631369.
[9] Bras ID, Colitz CM, Kusewitt DF, Chandler H, Lu P, Gemensky-Metzler AJ, Wilkie DA. Evaluation of advanced glycation end-products in diabetic and inherited canine cataracts. Graefes Arch Clin Exp Ophthalmol. 2007 Feb;245(2):249-57. doi: 10.1007/s00417-006-0293-7. PMID: 16896921.
[10] Weber K, Schmahl W, Münch G. Distribution of advanced glycation end products in the cerebellar neurons of dogs. Brain Res. 1998 Apr 27;791(1-2):11-7. doi: 10.1016/s0006-8993(97)01421-2. PMID: 9593803.
[11] Oba PM, Hwisa N, Huang X, Cadwallader KR, Swanson KS. Nutrient and Maillard reaction product concentrations of commercially available pet foods and treats. J Anim Sci. 2022 Nov 1;100(11):skac305. doi: 10.1093/jas/skac305. PMID: 36082767; PMCID: PMC9667973.
[12] Raditic DM. Insights into Commercial Pet Foods. Vet Clin North Am Small Anim Pract. 2021 May;51(3):551-562. doi: 10.1016/j.cvsm.2021.01.013. PMID: 33773645.

Important Considerations:

  • Always consult your veterinarian before making any significant dietary changes, particularly where there are pre-existing health conditions or dietary restrictions.
  • If you are feeding commercial food, check the label for ingredients before giving more. Excessive intake of any foods can have adverse effects.
  • Ensure (where possible) that you use high-quality, organic products specifically formulated for pets (or better still, human grade ingredients) to avoid any potential adverse effects.
  • Introduce new foods gradually to avoid adverse effects such as gastrointestinal upset or diarrhoea.
  • I provide nutritional information purely as a helpful guide. Nutritional information on ingredients is obtained from the US Department of Agriculture’s FoodData Central site (https://fdc.nal.usda.gov/index.html) and any nutritional information provided in recipes is based on an online calculator: calories and other information will vary based on brands, ingredients and other factors.
  • Check nutrient levels and recommendations for your dog’s weight, age and activity. For example this nutritional guideline produced by FEDIAF.
  • I am not a professional canine nutritionist but supporting research is cited.
  • The recipes shared were created by me and tested in my kitchen – and tasted and approved by our doggy friends!