Is collagen a complete protein?

You might already know that collagen production naturally declines as you age. But there’s another process that can influence how the collagen already in your skin behaves - glycation.

Glycation happens throughout the body and is a normal part of ageing. Over time, however, it can make collagen fibres stiffer and less flexible - potentially contributing to changes in the firmness, elasticity and appearance of your skin.

So, what exactly is glycation? Can eating sugar cause it? And is there anything you can realistically do about it?

Let’s break down the science without the scare stories.

What is glycation?

Glycation is a chemical reaction that occurs when certain sugars attach themselves to proteins or fats without the help of an enzyme.

Unlike glycosylation - a controlled biological process your body uses for many essential function - glycation happens spontaneously.

The process begins when a sugar molecule reacts with a protein. This can produce a series of unstable compounds which may eventually become advanced glycation end products, commonly shortened to AGEs.

Your body has ways to remove or repair some early glycation products. However, AGEs can be difficult to break down once they’ve formed, particularly when they affect long-lasting structural proteins, such as collagen.

This gradual accumulation is associated with normal ageing and may be accelerated by factors including persistently high blood glucose, oxidative stress, smoking and ultraviolet exposure.

Glucose is an important source of energy in the body. When present at high levels however, it can cause damage by sticking to the proteins and changing their structure and function. It’s a slow process, but hard to repair. Better dietary habits and increased use of antioxidants can help keep the damage at bay.

- Dr Dave Reilly, Senior Scientist.

What are advanced glycation end products?

Advanced glycation end products are compounds formed during the later stages of glycation.

AGEs can be produced inside the body, and some are also present in food. Research suggests that they can affect tissues in 2 broad ways:

• By attaching to and changing structural proteins such as collagen
• By interacting with cellular receptors, including the receptor for advanced glycation end products, or RAGE

Activation of these receptors is associated with oxidative stress and inflammatory signalling. However, AGE biology is complex, and much of the detailed research into skin glycation comes from laboratory, animal or observational studies rather than large human clinical trials.

AGEs shouldn’t be viewed as toxins that can be completely eliminated. They are compounds that naturally accumulate over time, although some health and lifestyle factors may influence the rate at which this happens.

How does glycation affect collagen?

Collagen is particularly vulnerable to glycation because it remains in the body for a relatively long time.

Collagen fibres form a supportive framework within the dermis - the deeper layer of your skin. Together with elastin and other components, this framework helps give skin its strength, firmness and flexibility.

When AGEs form cross-links between collagen fibres, those fibres may become stiffer, less flexible and more difficult for the body to re-model. Laboratory research has identified changes in the structure, stability and mechanical behaviour of glycated collagen.

Glycation may also interfere with normal interactions between collagen and surrounding skin cells. This could influence how effectively the skin maintains and repairs its extracellular matrix - the network of proteins and other molecules that supports its structure.

Research into glycated skin models has reported effects including altered collagen organisation, reduced elasticity and changes associated with cellular ageing. These findings help explain the possible mechanisms, but they don’t mean glycation is solely responsible for visible skin ageing.

“Collagen’s a protein that supports the skin for decades, but during that time can be subject to accumulated damage. The presence of advanced glycation products can create chemical rivets that harden the collagen, leading to loss of elasticity and firmness. This is very difficult to reverse or repair, so it’s important to protect your skin as much as possible and keep sugar-based damage to a minimum.”

• Dr Dave Reilly, Senior Scientist at Absolute Collagen

What does glycated skin look like?

There’s no reliable way to look in the mirror and conclude that a particular line or change in texture has been caused by glycation.

Skin ageing is influenced by many overlapping factors, including:

• Genetics
• Natural collagen loss
• Hormonal changes
• Sun exposure
• Smoking
• Air pollution
• Repeated facial movement
• Skin-barrier function
• General health
• Nutrition

Glycation may contribute to reduced elasticity, increased stiffness, dullness and the appearance of lines, but these changes aren’t unique to glycation.

Be cautious of online ‘sugar face’ checklists that claim to diagnose glycation from wrinkles, spots or dark circles. These features can have many possible causes, and glycation can’t be diagnosed from a photograph or social-media quiz.

Does eating sugar cause glycation?

Sugar is involved in glycation, but the claim that eating a sweet treat will immediately damage the collagen in your face is an enormous oversimplification.

Your body tightly regulates the amount of glucose in your bloodstream. Glycation occurs gradually, and the rate is influenced by factors including blood-glucose exposure over time, oxidative stress, age and overall metabolic health.

Persistently high blood glucose can accelerate AGE formation. This is one reason glycation is particularly relevant in research into diabetes and its complications.

For people without diabetes, occasional sugary foods can form part of a balanced diet. There’s no need to fear individual foods or attempt to remove every source of carbohydrate. Fruit, vegetables, pulses, dairy products and whole grains all contain carbohydrates while also supplying valuable nutrients.

A more useful approach is to consider your overall dietary pattern rather than labelling one ingredient as the cause of skin ageing.

If you have diabetes or are concerned about your blood-glucose levels, follow the advice of your doctor or diabetes-care team.

Do cooked foods contain AGEs?

Some AGEs form when food is cooked, particularly through dry, high-temperature methods such as grilling, frying and roasting. This is related to the Maillard reaction - the process that gives browned food its colour and flavour.

Lower-temperature, moisture-based cooking methods such as steaming, poaching, stewing and boiling generally create fewer dietary AGEs.

However, the relationship between dietary AGEs and visible skin ageing is not fully established. Foods containing AGEs are not automatically unhealthy and there isn’t enough evidence to suggest that everyone needs to follow a strict low-AGE diet for their skin. A varied diet containing vegetables, fruit, whole grains, pulses and appropriate protein sources remains a more practical foundation.

Can glycation be reversed?

Some early glycation reactions may be reversible. Established AGE cross-links in long-lived proteins such as collagen are much harder for the body to remove.

At present, there’s no skincare product, food or supplement proven to ‘unglycate’ all the collagen in your skin.

Scientists are investigating compounds that may reduce AGE formation, limit oxidative stress or affect AGE-related pathways. Much of this research remains experimental, and findings from a lab can’t automatically be translated into visible results in people.

The goal shouldn’t be to eliminate glycation completely - that’s not realistic. It’s more useful to focus on the everyday behaviours that support your skin and wider health.

How can you help protect your skin?

You can’t stop the passage of time, and we certainly wouldn’t want you to. Ageing is normal, natural and something to be embraced.

You can, however, reduce avoidable external stress on your skin.

Wear sunscreen consistently.

Ultraviolet radiation is one of the biggest preventable causes of premature skin ageing. UV exposure can contribute to oxidative stress and may interact with AGE-related pathways.

Use a broad-spectrum sunscreen and follow its application instructions. Remember to re-apply when needed, particularly after swimming, sweating or towelling.

Avoid smoking.

Smoking exposes the skin to oxidative stress and is associated with premature skin ageing. Observational research has also found associations between smoking behaviour and greater AGE accumulation.

If you smoke, support is available to help you stop. Your GP or local stop-smoking service can advise you.

Eat a varied, balanced diet.

Rather than pursuing an extreme ‘anti-glycation’ diet, concentrate on the overall quality of what you eat.

Try to include:

• A variety of colourful vegetables and fruit
• Beans, lentils and other pulses
• Wholegrain carbohydrates
• Suitable sources of dietary protein
• Nuts and seeds
• Adequate fluids

These foods provide nutrients that support your general health as well as the normal function of your skin.

Support healthy blood-glucose control.

Regular movement, a balanced diet, sufficient sleep and following any prescribed treatment can all contribute to metabolic health.

If you experience symptoms of high blood glucose or have concerns about diabetes, speak to a healthcare professional rather than trying to diagnose or treat the problem through skincare.

Keep your skincare routine consistent.

A gentle cleanser, moisturiser and broad-spectrum sunscreen provide a simple foundation.

Moisturising can’t remove existing AGE cross-links, but it can support the skin barrier and improve the appearance and feel of dry skin. Avoid overloading your routine with harsh products simply because they are marketed as ‘anti-glycation’.

Can collagen supplements prevent glycation?

Collagen supplements can’t completely prevent glycation or remove established AGEs from the skin.

Hydrolysed collagen provides collagen peptides and amino acids, but it shouldn’t be described as an antidote to sugar or a treatment for glycation.

Instead, collagen supplements can be considered as part of a broader routine that includes balanced nutrition, sun protection, movement and suitable skincare. No supplement compensates for smoking, unmanaged blood-glucose problems or excessive UV exposure.

It’s also important to separate 2 different processes:

• Collagen loss refers to the decline and breakdown of collagen over time
• Collagen glycation refers to chemical modifications that can make existing collagen fibres stiffer and harder to re-model

These processes can happen alongside each other, but they’re not the same thing.

Glycation versus collagen loss.

Both glycation and natural collagen loss may influence how skin changes with age.

Collagen production generally becomes less efficient over time, while existing fibres are also exposed to environmental stress and chemical changes. Glycation can create cross-links between collagen fibres, affecting their flexibility and organisation.

This means healthy-looking skin is governed by many things like genetics, hormones, sun exposure, lifestyle, skincare and wider health.

Any product promising to prevent every sign of ageing by targeting a single pathway should therefore be approached with caution.

So, what have we learned about glycation?

Glycation is a normal chemical process in which sugars attach to proteins or fats. Over time, this can lead to the formation of advanced glycation end products.

Because collagen is a long-lasting structural protein, AGEs can accumulate within it. The resulting cross-links may make collagen fibres stiffer and less flexible, potentially contributing to visible changes in the skin.

Glycation is a piece of a much bigger picture.

There’s no need to remove every carbohydrate from your diet, avoid all browned food or invest in a miracle ‘sugar detox’. Consistent sun protection, not smoking, balanced nutrition, movement and appropriate healthcare will do far more for your long-term health.

Ageing isn’t something that needs fixing. Understanding the biology simply helps you make informed choices about how you care for your skin.

Want to support your skin as it changes? Explore our collagen supplements or take the Absolute Collagen quiz to find the format that suits your routine.

Frequently asked questions.

Is glycation the same as ageing?

No. Glycation is one biological process associated with ageing, but it’s not the only cause. Genetics, hormones, UV exposure, smoking and natural collagen loss also affect the skin.

Can you see glycation on your face?

Not specifically. Glycation may contribute to stiffness, lines, dullness and reduced elasticity, but these changes can have many causes. You can’t accurately diagnose glycated skin by appearance alone.

Does quitting sugar reverse glycation?

No food change can guarantee the reversal of established AGE cross-links. Reducing excessive intake of foods high in free sugars may support wider health, but completely avoiding carbohydrates is unnecessary for most people.

Can skincare remove AGEs?

No topical product has been shown to remove all AGEs or reverse every glycated collagen cross-link in human skin. Some ingredients are being researched, but marketing claims may run ahead of the clinical evidence.

Does vitamin C stop glycation?

Vitamin C contributes to normal collagen formation and acts as an antioxidant, but it shouldn’t be presented as a treatment that stops or reverses glycation. It’s a nutrient within a much wider dietary pattern.

Does glycation happen only in people with diabetes?

No. Glycation occurs in everyone and is part of normal ageing. Persistently high blood glucose can accelerate AGE formation, which makes the process particularly relevant to diabetes.

Sources

• AGEing of collagen: the effects of glycation on collagen’s stability, mechanics and assembly
• Advanced glycation end products: key players in skin ageing?
• Biological effects induced by specific AGEs in a reconstructed skin model
• Investigating biochemical and structural changes in glycated collagen
• Advanced glycation end products: biochemistry and signalling
• Association between smoking and AGE accumulation