What Is Hyaluronic Acid?

Post by Troy Parkinson

Jun 18 2026

Hyaluronic acid (HA), also known as hyaluronan, is a substance naturally found throughout the human body. It is particularly abundant in tissues such as the skin, joints and eyes, where its ability to interact with water contributes to hydration, lubrication and the physical properties of surrounding tissues.

Chemically, hyaluronic acid is a glycosaminoglycan — a long-chain carbohydrate molecule made from repeating sugar units.

Despite the word “acid” in its name, hyaluronic acid is not an exfoliating acid like the alpha-hydroxy acids commonly encountered in skincare. Its name describes its chemical structure rather than suggesting that it is harsh or corrosive.

Today hyaluronic acid is used in several very different contexts, including skincare products, medical applications and oral supplements.

For a detailed look at marine collagen, hyaluronic acid, how they differ and how to choose, see our Complete Guide to Marine Collagen & Hyaluronic Acid.

Where Is Hyaluronic Acid Found in the Body?

Hyaluronic acid occurs naturally in the extracellular matrix — the material surrounding cells in many tissues.

Particularly notable concentrations occur in:

Skin, where HA forms part of the extracellular environment and interacts with water
Synovial fluid, the lubricating fluid found within movable joints
Cartilage and connective tissues
The vitreous humour of the eye, the gel-like material filling much of the eyeball

Its behaviour is closely related to its molecular structure and its strong interaction with water.

What Does Hyaluronic Acid Do?

One of hyaluronic acid's defining characteristics is its ability to bind and retain water.

This contributes to the viscosity and hydration of tissues containing HA. Within synovial fluid, for example, hyaluronic acid contributes to the fluid's physical and lubricating properties. In skin, naturally occurring HA forms part of the extracellular matrix and contributes to tissue hydration.

Hyaluronic acid also occurs in different molecular sizes, and molecular weight matters when examining its biological behaviour. This is one reason research involving one HA preparation shouldn't automatically be generalised to every other form.

Does Hyaluronic Acid Decline With Age?

The distribution and metabolism of hyaluronic acid in skin and other tissues change with ageing.

Age-related changes in skin involve far more than HA alone, however. Collagen, elastin, moisture content, sun exposure and numerous other biological and environmental factors are involved.

For that reason, it is too simplistic to describe ageing merely as the body “running out” of hyaluronic acid. The relationship between naturally occurring HA in human tissues and orally consumed supplemental HA is also more complicated than simply replacing depleted stores.

Topical vs Oral Hyaluronic Acid

Topical hyaluronic acid is commonly incorporated into skincare products because of its water-binding properties.

Oral hyaluronic acid is consumed in capsules, tablets, powders and other supplement formats. Research has investigated orally consumed HA in several areas, but its digestion, absorption and metabolism are different questions from HA's behaviour when applied directly to the skin.

Medical hyaluronic acid preparations are also used in specialised clinical applications. These shouldn't be confused with ordinary dietary supplements.

Evidence from one format therefore shouldn't automatically be applied to another.

Where Does Supplemental Hyaluronic Acid Come From?

Hyaluronic acid was historically obtained from animal tissues, including rooster combs. Modern commercial HA can also be produced through microbial fermentation, allowing hyaluronic acid to be manufactured without using animal tissue.

The source, molecular weight, purity and processing of HA can vary between products, so “hyaluronic acid” doesn't necessarily describe one completely uniform ingredient.

Hyaluronic Acid and Collagen

Hyaluronic acid and collagen are different substances with different structural roles.

Collagen is a structural protein found throughout connective tissues, including skin, bone, cartilage and tendons. Hyaluronic acid is a glycosaminoglycan whose physical properties are strongly associated with its interaction with water.

Because both occur naturally within connective tissues, they are frequently combined in modern supplement formulations. Their presence together in a product, however, doesn't mean they become the same substance or perform identical roles.

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