Bryan Johnson’s Dog Food Warning: AGEs Explained

Your dog’s food needs to do more than fill a bowl. Could the way it is made influence how well your dog ages?

Since adopting Katara, a Belgian Malinois, Bryan Johnson has turned some of his attention to canine longevity. In an August 2026 interview with Business Insider, he raised concerns about compounds in commercial dog food, describing them as things that “glue your organs together.” 1

The question behind that warning deserves attention: could we make everyday feeding choices that support better long-term health—not just meet basic nutritional requirements?

Food processing deserves a place in that conversation. Researchers have measured heat-related compounds in pet food, and studies in dogs have linked diet to differences in AGE-related measurements. 4 8

This is more than a question about whether food looks natural. It is a question about its chemistry—and what repeated exposure might mean over time.

What is behind the “gluing organs” idea?

The interview does not identify the specific compounds Johnson meant. One relevant area is advanced glycation end products, usually shortened to AGEs. Johnson’s own published protocol discusses cooking methods intended to reduce AGEs, although linking them to this particular warning remains an interpretation. 1 2

Glycation is a chemical process in which sugars and their reaction products modify proteins and other molecules. Some resulting AGEs can create crosslinks: extra chemical connections between proteins that would not otherwise be joined that way. Research in human tissues has identified the accumulation of these crosslinks with aging, including within collagen. 3

Think of a flexible material gradually acquiring unwanted connections between its strands. Those connections can alter how the material behaves. At the tissue level, this helps explain why glycation interests researchers studying aging—not because separate organs literally stick together. 3

Certain AGEs can also trigger cellular signaling associated with inflammation. Laboratory experiments have demonstrated this pathway, giving researchers another reason to investigate their effects beyond protein crosslinking. 7

There are also two sources to distinguish: AGEs formed within the body and AGEs already present in food. Their contribution to a dog’s overall exposure is not necessarily the same. Research in pet dogs has found dietary differences in urinary AGE markers consistent with absorption and subsequent excretion. 8

The important question is how much food-derived exposure contributes to tissue changes over a lifetime—and whether reducing it produces healthier years.

How cooking changes the picture

Cooking changes food chemistry, not just texture. The Maillard reaction—the chemistry behind much of the browning and flavor of cooked food—can produce AGEs. Food experiments show that moisture, temperature and cooking time influence their formation; moist cooking methods generally produce less of certain measured AGEs than intense dry heat. 9

There is a nutritional angle, too. Reactions involving lysine, an essential amino acid, can make some of it less available. Researchers have measured these processing-related changes in commercial pet foods. 4

This does not make cooking the enemy. Heating also helps control harmful microorganisms. The useful goal is enough processing to make food safe and suitable, while limiting unnecessary damage—not the least processing at any cost. 10

For an owner feeding the same recipe day after day, even a modest difference could be worth understanding. Repeated exposure is a reason to ask the question; it is not, by itself, proof of harm.

What have researchers actually found in dogs?

Different diets can change AGE markers in the body

A 2024 crossover study fed eight healthy beagles four diets: canned wet food, extruded kibble, air-dried food and mildly cooked food. Each dog tried all four, allowing researchers to compare responses within the same animals. 5

The canned diet produced the highest total concentration of the measured AGEs in plasma. The mildly cooked diet produced lower levels of some individual markers, including carboxymethyllysine (CML), than kibble. However, the difference between those two diets in the combined total was not statistically significant. 5

The takeaway is not that every processing method has a settled position on a health leaderboard. It is that what dogs eat can affect these biological measurements, with different compounds responding differently. 5

A year-long study found substantial differences in older dogs

In 2025, researchers followed 22 senior Alaskan sled dogs for 12 months, comparing an extruded diet with a complete fresh-food diet. 6

At month 12, the blood analysis reported approximately 46% lower relative abundance of CML and 94% lower relative abundance of pyrraline in the fresh-fed group compared with the kibble-fed group. These were differences in two AGE markers—not percentages of reduced aging or disease risk. 6

Those are substantial biological differences, not merely differences in how appealing the food looked. But the recipes also differed in ingredients and nutrient composition, so the results cannot be attributed to gentler cooking alone. 6

Together, these studies make the question worth taking seriously. They do not yet tell us whether reducing dietary AGEs prevents disease or extends a dog’s life. 5 6

That distinction leaves room for thoughtful action. For an owner deciding what to feed today, the choice is not between certainty and inaction. A plausible improvement may be worthwhile when it is affordable, nutritionally sound and does not introduce a larger risk.

CML and pyrraline: why do these markers matter?

These are not just obscure names on a lab report. They help researchers connect food chemistry with changes inside the body. Their possible effects are different, which is why it is useful to understand each one. 16 19 20

CML: a modified protein building block that can affect signaling

CML stands for Nε-(carboxymethyl)lysine. It is a chemically altered form of lysine, one of the amino acids used to build proteins. It can form through glycation and oxidation reactions in food and within the body. 11 16

CML is a non-crosslinking AGE: the modification does not itself create a bridge between two proteins. Its relevance is partly about the signals that modified proteins can send to cells. 16 17

Experimental research has shown that certain CML-modified proteins can engage RAGE—the receptor for advanced glycation end products. Think of RAGE as a sensor on a cell's surface. Its activation can turn on NF-κB, a molecular switch that increases the activity of genes involved in inflammation. That provides a plausible route from protein modification to altered cell behavior, without needing any literal “glue.” 16

The form matters. Structural research distinguished CML attached to a peptide—a short chain of amino acids—from free CML, which did not bind RAGE in that experimental context. Other studies using different CML-modified proteins have not reproduced inflammatory activation. The useful conclusion is that CML-related signaling depends on the surrounding molecule and experimental setting, not that every CML molecule inevitably causes inflammation. 17 18

Pyrraline: exposure, protein clearance and cellular defenses

Pyrraline is another chemical modification of lysine. It forms through reactions involving a sugar-derived intermediate called 3-deoxyglucosone. Researchers have detected it in both food-related Maillard chemistry and proteins within the human body. 19 20

It is especially useful as a clue to dietary exposure. In a controlled study in human volunteers, reducing Maillard-rich foods sharply lowered urinary pyrraline; reintroducing certain foods raised it again. This shows that at least some food-derived pyrraline is absorbed and subsequently excreted. 20

There is also a mechanism worth investigating beyond exposure. In experiments using a mouse macrophage-like cell line and human monocytes—types of immune cells—pyrraline-modified albumin was harder for lysosomal enzymes to break down. Lysosomes are the cell's recycling compartments. The modified protein accumulated more readily, raising the possibility that glycation can interfere with normal protein clearance. This was an experiment with modified protein, not proof that dietary pyrraline causes the same process in dogs. 22

Cellular responses are not uniformly inflammatory, either. A 2023 study in human colon cancer cells found that pyrraline-modified casein, a milk protein, activated Nrf2, a regulator of antioxidant and stress-defense genes. The researchers did not observe that response with free pyrraline. This does not establish pyrraline as beneficial; it shows why a modified protein, an isolated compound and a whole diet cannot be treated as interchangeable. 21

Where do actual protein crosslinks fit?

Glucosepane is an example of an AGE that really does form protein crosslinks. Researchers have measured its accumulation in aging human collagen. That is the structural side of the glycation concern; CML-related inflammatory signaling and pyrraline-related protein clearance are different possible routes. 3 16 22

These mechanisms give us meaningful questions to investigate. But a lower CML or pyrraline reading in a dog's blood does not directly measure fewer collagen crosslinks, less inflammation or better protein clearance. The canine feeding studies measured markers, not those downstream effects. 5 6

The opportunity is to understand which processing-related changes are avoidable and biologically important—not to assume every AGE behaves the same way.

Fresh, wet or kibble? The label is not the whole answer

A 2026 laboratory study examined 41 commercial dog foods. Wet foods had the highest average levels of the two AGEs measured, CML and CEL. Fresh foods had less lysine blockage than kibble—a measure of one type of processing-related nutritional loss. Fresh foods were not lower than kibble for every AGE measure. The researchers emphasized that both ingredients and processing conditions mattered. 11

These results caution against assuming that moist-looking food is always gently processed, or that a premium price guarantees less heat-related damage. The study found no consistent relationship between price category and the measured Maillard reaction products. 11

For owners, the useful questions are more specific: How is this recipe cooked? Is the finished product tested? What does it provide nutritionally? Does the manufacturer have evidence for its claims?

“Fresh” is a description, not a complete answer. So is “kibble.” A more useful standard is a well-formulated food, made with appropriate processing, supported by transparent information.

“Complete and balanced” is a foundation—not proof of optimal aging

A complete-and-balanced claim addresses nutritional adequacy. In the United States, it must be supported through an appropriate AAFCO nutrient profile or feeding trial procedures. It does not mean the food has beaten alternatives in a lifetime health comparison. 12

That is an important distinction. A diet can address recognized nutrient requirements while leaving other questions open: how processing affects it, how well it suits an individual dog, and whether another formulation could support better long-term outcomes.

Equally, a food does not become nutritionally adequate simply because its ingredients look fresh or familiar. A homemade mixture needs an appropriate formulation, not just good intentions. 12

We should protect nutritional adequacy while continuing to ask how nutrition could be better. Those goals reinforce each other.

What can you reasonably do now?

You do not need to make an all-or-nothing decision. Our practical approach is to look for plausible improvements without sacrificing something your dog already needs.

Consider a well-formulated, gently cooked option

For a healthy dog, exploring a nutritionally complete, gently cooked food is a reasonable option—not a demonstrated anti-aging treatment. The canine findings give this approach a scientific rationale, although a “fresh” label alone cannot tell you its AGE content. 5 11

A blended approach may also suit your household: retaining some complete kibble while substituting an appropriate complete cooked food. Choose both for your dog’s life stage and needs, and make the substitution by calories rather than equal scoop sizes. Nutritional adequacy and calorie content remain essential checks; no particular fresh-to-kibble ratio has been established by the studies discussed here. 12 13

A therapeutic diet is a different situation: changes should be planned with the clinician managing the condition, because substitutions may undermine the reason that diet was prescribed. 14

When cooking, avoid unnecessary browning—not proper food safety

For a food you are already preparing for your dog, poaching or steaming rather than heavily browning it is a sensible way to limit some heat-generated compounds. This advice comes from food-chemistry research, not a trial showing longer-lived dogs. 9

Still cook animal ingredients to a safe internal temperature. Gentler preparation should never mean undercooking. Nor does interest in lower-AGE feeding require a switch to raw food: raw pet foods can carry pathogens, creating a separate risk for dogs and people. 10

Keep substantial diet changes nutritionally complete

Replacing a little food is different from replacing half the diet with chicken and vegetables.

For ordinary unbalanced extras, a commonly used guideline is no more than about 10% of daily calories. That is a practical limit intended to reduce nutrient dilution, not a guarantee that every addition is appropriate. Larger homemade contributions deserve a properly formulated recipe. 12 13

A complete cooked food is different from an unbalanced topper. The important question is what the whole diet supplies.

Watch the dog, not just the ingredient list

Introduce changes gradually and follow weight, body condition, muscle condition, appetite, stool quality and activity. These observations help establish whether a feeding plan suits the dog in front of you. 14 15

These are checks on the diet’s everyday suitability, not proof that AGE exposure has fallen or aging has slowed.

There is also no need to turn a processing change into calorie restriction. Keep the feeding plan focused on supporting appropriate body condition and preserving muscle, rather than simply feeding less. 13 14

Nara’s take

Bryan Johnson’s warning is an opportunity to ask more of canine nutrition.

We do not have to choose between accepting every dramatic claim and assuming that established feeding practices cannot improve. The better question is what each piece of evidence helps us understand—and what decisions it reasonably supports.

Our view is that limiting avoidable heat-related changes is a reasonable nutritional goal when food safety, completeness and suitability for the dog are preserved. That is a case for thoughtful improvement—not fear-driven feeding. 9 10

The aim is not to win an argument about food formats. It is to build a feeding plan that makes sense for your dog, improve it where there is a good reason, and keep learning.

Start with a clearer picture of your dog’s diet.

Build your dog’s free Snapshot.

A note on research funding

The 2025 senior-dog study was funded by The Farmer’s Dog, which employed three authors. 6 The 2026 food analysis received Dogmates/Butternut Box funding and included an employee coauthor. 11 The 2014 analysis also had industry involvement, including Mars Petcare. 4

These relationships deserve transparency and make independent replication valuable; they do not, by themselves, invalidate the findings. The contrasting 2008 CML-signaling study also had Nestlé Research Center involvement. 18 The same scrutiny should apply regardless of which type of food a company sells.

Research checked: September 16, 2026. Research and writing were AI-assisted. This article has not been independently reviewed by a veterinarian. It provides educational information, not an individualized diet prescription.

Bryan Johnson’s Dog Food Warning: AGEs and Canine Longevity