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In a previous article, we provided a detailed introduction to botulinum toxin. Those interested can click to read it – Botox: From the most potent toxin to a beauty miracle drug? And in this article, we will introduce hyaluronic acid, the absolute dominant force in the field of medical aesthetics injections.
Part 01. History
First, let’s look at how it was discovered. In 1934, Karl Meyer, a professor at Columbia University, isolated a previously unknown substance from the vitreous humour of a cow’s eye. As it contained uronic acid and was transparent like glass, he named it hyaluronic acid. Subsequently, the professor and his team discovered hyaluronic acid in various human and animal tissues, including skin, umbilical cords, joint fluid and rooster combs. Of these, rooster combs and umbilical cords were found to have the highest content. However, extracting hyaluronic acid on a large scale from human umbilical cords was clearly impractical, so scientists turned their attention to roosters.
In 1949, Swedish scientist Laurent and American scientist Balazs collaborated on research into extracting hyaluronic acid from chicken combs on a large scale. They finally developed a process for separating and purifying hyaluronic acid in the 1970s, thus enabling its mass production from chicken combs. However, this method has an extremely low extraction rate of only about 1%, and the separation process is also very complex. These factors make hyaluronic acid expensive, which limits its widespread use in daily cosmetics. A chicken comb weighs approximately 10 g. Extracting 1 kg of hyaluronic acid requires about 200 kg of chicken combs, equivalent to 20,000 combs. This means that 20,000 roosters need to be slaughtered. Based on this calculation method, producing 1 g of hyaluronic acid required an investment of around $100 at that time, whereas the price of 1 g of gold was only $6.25. (Injectable raw materials were calculated to cost $100,000 per kg, using prices from the 1970s as a reference.)
At that time, it was primarily used to treat eye and joint diseases. Additionally, major horse racing organisations would inject hyaluronic acid into the joints of racehorses to lubricate them. In the 1980s, Japan pioneered the production of hyaluronic acid through microbial fermentation. The biggest advantage of this method was that the source of the raw material was unlimited, which greatly simplified the process, reduced production costs and minimised the risk of viral contamination. This enabled large-scale industrial production. Consequently, the price dropped significantly. It was only then that hyaluronic acid began to be used in beauty and skincare products.
Part 02. Application
Various advertisements often claim that hyaluronic acid provides hydration and feature concepts such as large-molecule, small-molecule and mini-molecule hyaluronic acid. But are these claims true, or are they just marketing gimmicks? The fact is that hyaluronic acid has extremely strong hydrophilic properties. One hyaluronic acid molecule can bind up to 1,000 water molecules, making it one of the most effective moisturising substances found in nature for use in cosmetics. The different types of hyaluronic acid exist because it is an organic polymer with a variable molecular weight, generally ranging from a few thousand to 3 million Daltons. It can therefore be classified into low-, medium-, and high-molecular-weight categories, which can be understood as different concentrations. Different fields such as orthopaedics, ophthalmology, surgery, medical aesthetics and food have different requirements for the molecular weight of hyaluronic acid. For instance, in medical aesthetics, different grades of hyaluronic acid penetrate different layers of the skin to varying degrees. In skincare products, high-molecular-weight hyaluronic acid can only act on the sebum film. Only small-molecule hyaluronic acid with a molecular weight of less than 1 million can penetrate the epidermis and soften the stratum corneum. Only mini-hyaluronic acid with a molecular weight of less than 10,000 can penetrate the dermis.
As mentioned earlier regarding botulinum toxin, hyaluronic acid was first widely used in ophthalmology to treat dry eye syndrome. Hyaluronic acid eye drops have excellent water-retaining and lubricating properties, as well as anti-inflammatory and reparative capabilities. Another common application is in orthopaedics. Due to the long-term strain of supporting the body’s weight, our joints are prone to inflammation. Many clinical trials have confirmed the efficacy of hyaluronic acid in treating early to mid-stage osteoarthritis and knee pain.
Many people may not be aware that hyaluronic acid is a key component of the intercellular matrix, the vitreous humour of the eye and the synovial fluid in joints. Our bodies naturally contain around 15 g of hyaluronic acid. As well as moisturising and hydrating, it plays an important role in promoting cell repair. However, the body’s ability to produce hyaluronic acid declines with age and due to environmental factors. Skin hyaluronic acid production begins to decrease after the age of 25, reaching just 65% of childhood levels by the age of 30 and only 25% by the age of 60. Along with hyaluronic acid, skin moisture is also lost, leading to a loss of elasticity and radiance, and eventually wrinkles and other signs of ageing. Consequently, many beauty enthusiasts opt for hyaluronic acid injections to achieve a more youthful appearance. These injections can effectively address various types of wrinkles, including frown lines, crow’s feet, marionette lines, nasolabial folds and perioral wrinkles. In addition to reducing wrinkles, hyaluronic acid also has a sculpting and shaping effect. Procedures such as lip augmentation and rhinoplasty often use hyaluronic acid injections to achieve the desired results.
Part 03. Future
