In 1912 the French chemist Louis-Camille Maillard described a reaction that gives bread its crust. A century later biologists realised the same reaction runs inside our bodies, just slower and at 37 degrees Celsius. It is called glycation and it explains why skin stiffens and why we age faster. Here is what science says about caramelising human tissues from the inside.

Key facts about glycation:

Definition: glycation is a non-enzymatic reaction between sugar and protein.
AGEs: advanced glycation end-products that stick proteins together.
Skin: collagen glycation drives stiffness and deeper wrinkles.
Diet: grilling generates many times more AGEs than boiling.
Control: stable glucose and a low-GI diet cut the glycation load.

What exactly is glycation?

So what exactly is glycation? It is the spontaneous attachment of a sugar molecule to a protein or fat, without an enzyme. In contrast with glycosylation (the controlled process in which enzymes deliberately attach sugars to proteins), glycation happens in a chaotic way. Glycation of proteins affects collagen, elastin and many other structures – once glued to sugar, they stop fitting their receptors, like a key coated in resin.

What is the Maillard reaction inside the body?

The Maillard reaction is an uncontrolled caramelisation of proteins at 37 degrees Celsius. In an oven it defines the smell of bread; in the body it runs thousands of times more slowly, yet runs around the clock and accumulates over decades.

What are AGEs (advanced glycation end-products)?

AGEs are permanently altered proteins to which sugar has attached. Once formed, they practically never return to their original form. The body clears some of them, but removal cannot keep up with formation when blood sugar is chronically high. They accumulate where long-lived proteins reside – in collagen, arteries and the eye lens.

How does glycation age skin and tissues?

Glycation changes skin mechanics from the inside. When sugar cross-links collagen and elastin, the network becomes stiff and less elastic. Glycation of tissues also shows up as stiffer arteries. A study by Monnier and colleagues in Diabetes (1999) showed that collagen cross-linking in long-standing type 1 diabetes was several times higher than normal. On top of that comes photoageing of the skin.

What happens to collagen when it „caramelises”?

Glycation of collagen creates permanent bridges between fibres. Healthy collagen stretches and recoils; sugar-linked collagen has less elasticity. Skin holds water less well and minor injuries heal more slowly.

Why do people with diabetes age faster?

Chronically high glucose means accelerated glycation. Glycated haemoglobin HbA1c is a blood protein permanently joined with sugar – the best clinical picture of the process. People with poorly controlled diabetes tend to meet arterial stiffness and slower wound healing earlier. More on type 2 diabetes.

How do diet and cooking methods influence AGEs?

AGEs form in the body from glucose or arrive with food. The latter, called dietary AGEs, appear when protein-rich food meets high dry heat. Grilling and frying generate many times more than boiling. More on the glycaemic index and the low-GI diet.

Which foods contain the most AGEs?

A study by Uribarri and colleagues at Mount Sinai published in the Journal of the American Dietetic Association in 2010 measured the AGE load in over five hundred products. Differences between the same ingredient boiled and roasted were more than tenfold. The table below compares AGEs by cooking method:

Category	High AGEs	Low AGEs
Meat	Grilled, fried	Stewed, boiled
Cheese	Hard, processed	Cottage, mozzarella
Vegetables	Chips, crisps	Raw, steamed

How to cook in order to limit glycation?

The rule is simple: more water, lower temperature, shorter time.

Cooking methods friendly to low glycation:

Boiling and steaming: temperature stays below 100 degrees, the reaction barely starts.
Stewing with a lid: steam keeps moisture in and meat does not sear.
Acid marinades: vinegar and lemon juice reduce AGE formation during roasting.
More plants on the plate: vegetables and pulses hold less protein and produce fewer AGEs.

Do carnosine and other supplements help?

Carnosine is a dipeptide (a molecule made of two amino acids) naturally present in young muscle tissue. In lab studies it acts as a scavenger of intermediate molecules in AGE formation. Human clinical evidence is limited – swapping the pan for a pot will bring a bigger return than the supplement shelf.

Does blood sugar control reduce glycation?

Yes, keeping blood sugar stable is the strongest lever against glycation we have. Dr David Sinclair of Harvard Medical School often repeats that „every point of HbA1c above target represents measurable acceleration of biological ageing”. The lower the average glucose, the fewer molecules collide with proteins.

Habits that support stable blood glucose:

Order of eating: start with vegetables and protein, finish with carbohydrates.
Post-meal movement: a 10-15 minute gentle walk flattens the glucose peak.
Fibre at every meal: slows sugar absorption.
Fewer sugary drinks: liquid sugar hits the bloodstream faster than solid form.

How does glycation connect to oxidative stress?

AGEs and free radicals drive each other. By binding to RAGE receptors (the AGE receptor that triggers inflammation), AGEs push cells to produce more free radicals, which then accelerate the formation of new AGEs. A vicious circle emerges and glycation fuels low-grade inflammation in adipose tissue. More in the article on oxidative stress and free radicals.

How to reduce glycation in everyday life

It comes down to three layers: stable blood sugar, smarter cooking and lifestyle basics. How to prevent glycation day to day? Through the accumulation of small changes – one-off pushes will not do the job. In metabolic conditions, especially in diabetes, dietary changes should be discussed with the treating physician.

This article is educational and does not replace medical advice. People with diabetes or insulin resistance should discuss dietary changes with their treating physician.

FAQ: Frequently asked questions about glycation

What is glycation and why is it harmful?

Glycation is a non-enzymatic reaction between sugar and proteins that produces permanent AGEs, which stiffen tissues and accelerate ageing.

Which foods speed up glycation?

The strongest accelerators are sugary drinks, white sugar, glucose-fructose syrups and heavily browned meats.

How should I cook to limit AGEs?

Choose boiling, steaming and stewing under a lid, and marinate meat in acidic mixtures before any roasting.

Is glycation reversible?

Early stages regress when blood sugar normalises, but mature AGEs stay in tissues – so prevention matters more than reversal.

References:

Monnier V.M., Bautista O., Kenny D. et al. (1999). Skin collagen glycation, glycoxidation, and crosslinking in relation to diabetes complications. Diabetes. https://doi.org/10.2337/diabetes.48.4.870
Uribarri J., Woodruff S., Goodman S. et al. (2010). Advanced glycation end products in foods and a practical guide to their reduction in the diet. Journal of the American Dietetic Association. https://doi.org/10.1016/j.jada.2010.03.018