Happy new year! I hope you had a great holiday and are feeling refreshed and ready to take on 2020. If you're like me, you probably did some traveling over the holidays. I visited Las Vegas for Thanksgiving and New York state for Christmas, subjecting my skin to drier and colder weather than it's used to in Los Angeles. I was reminded of my years spent battling the effects of winter weather on my skin and felt inspired to post about the famously hydrating skincare ingredient, hyaluronic acid.
Hydration 101
Hyaluronic acid is known as a top raw material for skin hydration, but what does that mean? Hyaluronic acid is part of a family of ingredients called humectants that help with dehydrated skin. These ingredients work by absorbing water from the atmosphere or your skin and holding it in place. This is not the same as moisturizing ingredients, called occlusive agents or emollients, which help with dry skin. Moisturizers decrease water loss by forming a barrier on the skin's surface that prevents water from escaping. In general, moisturizers are oil-based ingredients and hydrators are water-based.
How can you tell whether your skin is in need of hydrating or moisturizing? You may not need to worry, as many lotions and creams contain both types of ingredients. However, if your skin is dry year-round and you experience symptoms like flaking and itching, your skin may need help retaining moisture and could benefit from moisturizing ingredients such as shea butter, lanolin, petroleum jelly, mineral oil, or natural oils such as coconut, hemp, jojoba, or squalene. A thick moisturizer will create a protective seal on the skin's surface and restore the natural barrier of oil that protects your skin.
Dry skin lacks oil, but dehydrated skin lacks water. Adding water back into the skin is where hyaluronic acid shines! Other hydrating ingredients include glycerin, aloe, honey, and citric acid. You can also hydrate the old-fashioned way by drinking water and eating foods with a high water content. While dry skin is typically a year-long skin condition, dehydration is generally caused by external factors like weather, environment and diet. Signs of dehydrated skin are tightness, redness, dull appearance, and exaggerated wrinkles or dark circles under the eyes. Adding a hydrating skincare product with hyaluronic acid will counteract these symptoms and result in plumper, softer, and smoother skin.
Chemical Names
Hyaluronic acid is naturally produced in the skin and plays a major role in tissue structure and repair. Hyaluronic acid and its sodium salt form, sodium hyaluronate, are the two common names that can be found in the ingredient listing of skincare products. The name hyaluronan is prevalent in medical uses because the form that is commonly synthesized is a salt, not an acid.
Regulation
Hyaluronic acid is FDA approved for use as a dermal filler in cosmetic surgery under a variety of brand names, but there is no FDA monograph for its use in topical skincare products. This means that products with hyaluronic acid are regulated as cosmetics, not over-the-counter (OTC) drugs. This categorization limits labeling requirements and regulatory oversight and the claims that can be made for the products. For a refresher on FDA monographs and cosmetic claims, refer to Cosmetic or Drug? Regulatory Basics and FDA Monographs.
Mechanism
So how does hyaluronic acid work? Hyaluronic acid is similar to collagen and elastin in that it is naturally occurring in the body but its levels decrease with age. A commonly cited statistic is its ability to hold a thousand times its molecular weight in water. The most effective forms of hyaluronic acid are smaller molecule sizes that are able to penetrate deep into the skin. Large molecule sizes tend to sit on the surface of the skin and therefore do not affect deeper skin layers. Some brands include information on molecular sizes for their products. For example, The Ordinary's Hyaluronic Acid 2% + B5 states "This formulation combines low, medium, and high molecular weight hyaluronic acid, as well as a next-generation H.A. crosspolymer at a combined concentration of two percent for multi-depth hydration." Not all hyaluronic acid products are created equal. Naturally-occurring hyaluronic acid has a relatively short shelf life, so manufacturers have worked to extend the length of the polysaccharide chain and stabilize the molecule. Different combinations of molecular weights and stability can be found on the market.
Consumer Considerations
For many other ingredients, I've included sections on how they readily degrade upon contact with air or may not work well for people with sensitive skin. Hyaluronic acid does not have those issues. It can be stored in transparent packaging and is gentle on skin. It should work well for all skin types. As with all ingredients, I recommend trying different formulations to see what works best for you. There are lots of products on the market with this powerful ingredient, from makeup to cleansers and creams to simple serums. In general, hyaluronic acid works well in serums. In that form, the hydrating properties of the light serum can be applied early in your skincare routine and then followed with a heavier moisturizer that will seal it in with the oil barrier.
Final Thoughts
I hope you found today's post informative and learned all about the common hydrating ingredient, hyaluronic acid. If you'd like to learn more about raw materials, check out Ingredients 101: Cosmetic Ingredients Broken Down by Source, Class, and Function or these articles on top skincare ingredients: Retinol, Salicylic Acid, and Vitamin C. Do you have more questions on hyaluronic acid? Is there another ingredient that you would like to learn about? Let me know in the comments!