Collagen is the most abundant protein in the human body and is often referred to as the glue that holds the body together. Its importance is most evident in the skin.

It is no wonder that the word collagen is derived from the Greek kolla, meaning glue,¹ because of its incredible ability to hold the body together. In this article, we will explore the importance of collagen and its function within the dermis layer of the skin, the main types of collagens found within the skin, and how they each contribute to the overall health and appearance of the skin.

Collagen is the primary component of the extracellular matrix

In the skin, collagen is present as long fibres within the extracellular matrix of the dermis, the thickest layer of skin.^2,3 Incredibly, excluding water, collagen accounts for a massive 75% of the skin by weight.³

The primary function of collagen in the extracellular matrix is to maintain the structural integrity of the skin, giving it mechanical stability, elasticity, and strength.²

Collagen is an essential protein that forms the structural foundation of the skin, specifically within the extracellular matrix of the skin’s dermis layer.^2,3

The collagen-rich extracellular matrix plays an indispensable role in providing an environment in which the cells of the skin can thrive; an environment where cells can build and repair skin components to maintain structural integrity and function.^2-4 Importantly, collagen fibres within the extracellular matrix provide the skin with tensile strength, durability, and elasticity, which together allow the skin to bounce back.³

The role of collagen in ageing skin

Changes to the skin are often a telltale sign of ageing, with fine lines and thinning skin occurring naturally as we age, alongside stress-induced changes, like deep wrinkles and loss of elasticity.³

In young and youthful skin, collagen fibres are abundant, tightly packed, and well-organised.³ However, in contrast, older and ageing skin contains collagen fibres that are often fragmented and distributed unevenly, resulting in the telltale signs of ageing.³

Both wrinkles and loss of elasticity caused by the ageing process have been linked to progressive thinning of the skin. Thinning of the skin includes a decrease in the amount of extracellular matrix, which is itself driven by a reduction of Collagen.³

The collagen-rich extracellular matrix can also break down during ageing, becoming disparate and unevenly distributed. This process is driven by an overall decline in the amount of collagen in the skin, caused by both decreased production of collagen as well as increased breakdown of collagen.³

Overall, the reduction of collagen in ageing skin can cause the skin to undergo significant changes, contributing to the emergence of ageing features such as wrinkles and reduced skin elasticity.³

Collagen in the skin

Collagen is distinguished by its unique and intricate triple helix arrangement, which is the key to its distinctive and versatile properties. In the skin, collagen’s main properties influence firmness, strength, and elasticity.²

Amazingly, there are at least 28 distinct collagen types found all over the body, but the skin primarily consists of only three types: Collagen types 1, 3 and 5.⁵

Collagen in the skin has three distinct types, each with their own unique role

Type 1	Type 3	Type 5
80 – 90%	8 – 12%	Less than 5%
Structural support and strength	Creating and organising type 1 collagen	Regulating the size and organisation of collagen
Firmness and durability	Elasticity	Balancing firmness and elasticity

Type 1 collagen

Type 1 collagen is the most abundant form of collagen in the skin, comprising 80% to 90% of the total collagen in the skin.³ It is densely packed, forming compact fibres that provide structural support and strength to the skin.⁶

Type 1 is the most significant a pivotal role in maintaining the skin’s firmness and durability.⁶

As we age, the production of Type I collagen declines, leading to a loss of skin elasticity and the appearance of wrinkles.⁴

Type 3 collagen

Type 3 collagen makes up 8% to 12% of the total collagen in the skin and is often found alongside Type 1 collagen, which collectively contributes to almost 95% of the skin’s structure.^3,5

Type 3 collagen plays a crucial role in the formation of Type 1 collagen by organising the densely packed Type 1 collagen fibres.^2,5

Type 3 collagen is important for skin elasticity.²

Type 5 collagen

Although Type 5 collagen makes up less than 5% of the total collagen in the skin,³ it has a vital role in regulating the organisation and size of collagen fibres in the skin.⁷

Specifically, Type 5 collagen provides structural support. It regulates the diameter or thickness of collagen fibres which in turn influences the organisation of fibres. In doing so, Type 5 collagen is crucial for influencing the balance between firmness and elasticity of the skin.^5,7

Understanding the different types of collagen and their roles may prove useful when adopting a skincare regime. Collagen underpins the structural integrity of the skin, with the various types of collagen working in unison to balance strength, firmness, and elasticity.^2-4 Supporting collagen production in the skin could hold promising potential in maintaining youthful and radiant skin as we age.⁵

References

1. “Collagen.” Oxford Advanced Learner’s Dictionary. Accessed [Date accessed: 27 March 2024]. Available from: https://www.oxfordlearnersdictionaries.com/definition/english/collagen?q=collagen
2. Wang H. Polymers (Basel). 2023 Oct 5;15(19):3999.
3. Shin JW, et al. Int J Mol Sci. 2019 Apr 29;20(9):2126.
4. Campos LD, et al. Heliyon. 2023 Mar 28;9(4):e14961.
5. Liu H, et al. Photodermatol Photoimmunol Photomed. 2024 Jan;40(1):e12931.
6. Pu SY, et al. Nutrients. 2023 Apr 26;15(9):2080.
7. Wenstrup RJ, et al. J Biol Chem. 2004 Dec 17;279(51):53331-7.

Have you ever wondered how your favourite moisturiser makes your skin feel soft, smooth, and supple?¹ There is a good chance that glycerol, an ingredient first recognised for its beneficial effects on the skin over 90 years ago, underpins the hydrating effect of your favourite skincare products.¹

When it comes to skincare, it is important to have ingredients that you can rely on to support healthy, hydrated skin. In this article, we shine a spotlight on glycerol, how it works, and why you should look for it in your skincare products.

What is glycerol?

Also known as glycerine, glycerol is a potent humectant that has powerful hydrating effects.¹ Glycerol is a common ingredient in topical skin preparations to promote hydration and can be injected intradermally to achieve deep hydration.^1,2

Glycerol is a simple molecule that is extremely hydroscopic, which means it strongly attracts water₁ and it is this water-attracting property that is responsible for glycerol’s beneficial effects on the skin.¹

Glycerol is naturally produced by our bodies as part of the skin’s Natural Moisturising Factor (NMF), alongside other components.¹ Working alongside other components of the NMF, glycerol helps to maintain adequate skin hydration and skin barrier health.¹ In addition, glycerol can pass through aquaporins, which are proteins that channel the flow of important hydrating substances to the skin’s layers.¹ Together, they play a key role in maintaining skin’s moisture balance, helping it to feel smooth and comfortable.³

How does glycerol work in the skin?

Glycerol is a humectant, which means that glycerol can both attract and hold water. This means that when glycerol is present in the layers of your skin, it both draws water from its surroundings and locks it in place, improving the skin’s water content and hydration levels.¹

“Glycerol’s ability to attract and preserve hydration makes it a potent humectant, a property which underpins many of its key benefits.”¹

Moisturiser products typically contain a combination of humectants (molecules which introduce water to the skin), emollients(molecules which introduce oil to the skin) and occlusives (molecules which prevent water loss through the skin).⁴ Glycerol is used extensively as a hydrating humectants in skincare products such as gels and lightweight moisturising products.⁴

Glycerol is one of the most effective humectants: it is a simple, small molecule which means that it can penetrate deep into the skin’s layers. An important property of glycerol is that it does not evaporate away, which means it remains in the skin exerting its effect for a longer period of time.⁵

Why is skin hydration important?

Our skin is constantly exposed to the elements, which can strip it of its natural hydration and oils.¹ Hydrated skin is more likely to look and feel healthy. It has been shown that low hydration levels can hinder the activity of other molecules in the skin, like proteins and enzymes.⁶ Some of the benefits of including glycerol as a staple in your skincare include:

• Skin moisturisation: Glycerol spreads easily into the layers of the skin where it is able to attract and retain nearby water.1 This effect is sometimes referred to as ‘bulking’, which further helps your skin to feel plump and healthy, minimising fine lines and wrinkles.⁷

• Skin barrier maintenance: Glycerol has been shown to interact with the skin barrier to help maintain its integrity.¹ Boosting the protective and hydrating function of the skin barrier prevents water loss and shields against external stress from the environment.^1,4

• Boosts skin elasticity: Glycerol’s effect on the outermost layers of the skin boosts elasticity and hydration, helping your skin feel supple and healthy.¹ When skin elasticity is optimised, it is better able to resist mechanical stress from body movement, like rubbing, stretching, and compression.¹

• Skin cell turnover and renewal: Our skin naturally undergoes a turnover process to shed old skin cells and reveal fresh, healthy skin.1 Glycerol’s water-attracting properties actively support this natural turnover process, resulting in improved skin appearance and overall skin health.₁ By helping in the removal of dead skill cells, glycerol promotes more radiant skin.⁸

It is also important to consider which ingredients are used to attract water to the skin. While all humectants can attract water, glycerol stands out due to its ability to be transported by aquaporins, which are protein channels in the skin. This means that glycerol can pass deeper into the skin’s layers and exert its beneficial effects, providing deep hydration.⁹

Glycerol for skin hydration

Glycerol is one of the simplest, yet most powerful ingredients in your toolbox when it  comes to caring for your skin. Including glycerol-containing products in your skincare routine can promote skin hydration and can offer several benefits by helping to moisturise the skin, maintain the skin barrier, boost elasticity, and support skin cell turnover and renewal.

References: 1. Fluhr JW, et al. Br. J. Dermatol. 2008;159:23–34. 2. Hertz-Kleptow D, et al. Clin Cosmet Investig Dermatol. 2019 Aug 13;12:563-572. 3. Rawlings AV, Matts PJ. Stratum corneum moisturization at the molecular level: an update in relation to the dry skin cycle. J Invest Dermatol. 2005 Jun;124(6):1099-110. 4. Barnes TM, et al. Pharmaceutics. 2021;13(12):2012. 5. (Zhang 2014) Zhang H, Grinsta MW. Macromol Rapid Commun. 2014;35(22):1906-1924. 6. Haftek M, et al. J Drugs Dermatol. 2021;20(4):s3-s9. 7. Batt MD, et al. J Soc Cosmet Chem. 1988;39:367-381. 8. Schwartz J, et al. J Drugs Dermatol. 2016;15:1289;1294. 9. Hara-Chikuma M, et al. Physiological roles of glycerol-transporting aquaporins: the aquaglyceroporins. Cell Mol Life Sci. 2006 Jun;63(12):1386-92.