Hyaluronic acid, also known as HA or hyaluronan, is a glycosaminoglycan that is naturally present in many areas of the human body, particularly the joints, eyes and skin. As part of the mammalian connective tissue, it helps to draw moisture into the skin to give it volume while binding collagen and elastin fibres to give the skin its structure.

From being traditionally used in clinics, HA has now entered the realm of cosmetics and skincare. This substance is often recommended by many beauty magazines as one of the top ingredients for injectable dermal fillers and topical skincare products such as serums, creams and makeup.

History and importance of hyaluronic acid

HA has a long history that dates back to 1934 in Columbia University, New York City. Two American scientists - Karl Meyer, a pioneer of glycosaminoglycan chemistry and his assistant John Palmer, first discovered it in the vitreous of bovine eyes. 

Together with the uronic sugar found with it, it was first named as “hyalos”, meaning glass in Greek. Later, HA was commercialised by Endre Balazs, who used it as a substitute for egg white in bakery products.

In the next 50 years, Balazs discovered more uses for HA. Now, HA has wide clinical use such as in eye surgeries, wound repairs and treatment of arthritis joints. HA was originally extracted from rooster combs for medicinal usage, however it can now be synthesised from lab-cultured bacteria, bearing close structural resemblance to natural HA.

HA is a major component of the extracellular environment, with the average human body containing around 15 grams of natural HA. Therefore, in clinical medicine, HA serves as an important diagnostic marker for diseases such as cancer, rheumatoid arthritis and liver pathologies.

It is an approved substance for the treatment of several joint disorders including osteoarthritis, and the replacement of natural fluids during eye surgeries such as cataract removal, detached retina and corneal transplantation. Other usages of HA include cosmetic regeneration and soft tissue reconstruction.

The “fountain of youth”

Since HA cannot be stored in the body, and the production of HA gradually gets less efficient, with age the skin experiences an increase in dryness, wrinkles, fine lines and sagging. As such, skincare and cosmetic products proudly list HA as one of their ingredients, claiming to replenish this diminishing natural substance.

Some products associate HA with being the “fountain of youth” by being anti-wrinkling, along with exceptional moisturising properties for the skin.

Dermatologists, however, critique that there might be a misconception that HA can be absorbed through the skin to decrease the appearance of ageing. Since regular HA is a large molecule, it cannot really be absorbed through the pores of the skin to act on the deeper areas if it is applied topically.

This has led to the production of alternatives to regular HA. Sodium hyaluronate, a salt derived from hyaluronic acid, is said to not only be more easily absorbed than HA, but is also a cheaper ingredient. Scientists have also synthesised smaller-sized nano-HA to increase the absorbance of HA through the pores of the skin.

Unique molecular properties

When used in topical products like moisturisers and serums, HA showcases a very unique property - its ability to hold in an exceptionally high amount of moisture. The large molecular size of the regular HA allows it to remain at the top of the skin, drawing both moisture from the water that the HA was dissolved in, or attracting moisture from the environment itself.

Together with the water molecules, HA forms a barrier on the skin and gives it a moisturising effect. Some skincare products are made up of a combination of different types of HA dissolved in fluid solution. While the larger HA sits on the outer epidermis, the smaller HA can enter the pores to act on the deeper parts of the skin.

However, dermatologists warn that HA can adjust its moisture absorption based on humidity. As such, climate and season are important factors when using HA-containing products.

HA, a water-binding substance, could be less beneficial in dry climates. It may not be able to draw moisture from the environment and may instead pull moisture out of the deeper layers of the skin, thus drying it out. Dermatologists also stress that HA should not be used in its pure form, but instead mixed with other substances along with water.

Hence, due to its unique properties, HA is increasingly used in research which have provided many benefits in clinical as well as cosmetic use. MIMS

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