As a 35-year-old esthetician and skin care product maker trained in cosmetic chemistry, what I know for sure is that there is a lot of false hope out there for the latest and greatest “miracle” ingredients – and it’s so easy to fall for the marketing hype.
I’ve seen many ingredients come and go (hello hyaluronic acid!) but the one that has remained constant is vitamin C. Why? Because it works on evening pigmentation by interrupting the overproduction of melanin that causes hyperpigmentation. In addition, working with facials, I have seen incredible improvements in my clients’ skin, giving their skin the radiance they desire.
But…it is not all vitamin C ingredients and what is currently considered “the gold standard” is Tetrahexyldecyl Ascorbate, also known as THD Ascorbate.
So, let’s take a deep dive into this ingredient, shall we?
What is THD Ascorbate?
THD, or Tetrahexyldecyl Ascorbate, is an inactive form of Vitamin C. What makes THD Ascorbate so uniquely different from other forms of Vitamin C is that it is an oil-soluble ester versus a water-soluble one. Being oil-soluble means it won’t start to react and turn into L-ascorbic acid until it hits the oils on your skin, making it more stable compared to other forms of vitamin C. Plus, since it’s soluble in oil instead of water, it doesn’t require a low pH like water-soluble versions.
Why should I choose THD ascorbic over other types of vitamin C for my face?
Have you ever felt a stinging sensation from vitamin C products with ascorbic acid, sodium ascorbyl phosphate, and ascorbyl methylsilanol pectin? Yes, this is an indication of their low pH along with possibly the condition of your skin barrier. While the sting from low-pH vitamin C is par for the course, (read more about the sting from skincare products), that doesn’t mean your skin appreciates the daily “no pain, no gain” assault it’s exposed to in the quest for brighter skin. Your skin’s pH is around 5.0, and many of the water-soluble acids can be pH 4.0 or lower, so that’s where the “oooh factor” comes from.
Just like exercise, if you want to achieve results for your body and your overall health and longevity, you need to create some discomfort. But for skin, I like to leave them for retinol, prescription retinoids, at-home peels, 7-day skin challenge, and professional treatments like micro needling, dermaplaning, lasers (like the Moxi laser I had on my own skin), and chemical peels.
If your goal is to create a smoother, more even texture with less visible pores, there will be side effects that can compromise the skin barrier and cause irritation, but putting your skin in a heightened state of sensitivity every morning by using a low pH vitamin C serum? No. I’m not a fan of this at all.
(If you feel like your barrier is broken, see how to fix it.)
How effective is THD Ascorbate in reducing brown spots and hyperpigmentation?
I was introduced to Tetrahexyldecyl Ascorbate in 2004 while searching for better solutions for my clients struggling with hyperpigmentation from the sun, hormones and breakouts. At first, I was sold a 2% Hydroquinone product to target pigmentation that is still known to be very effective, but during a cosmetic chemistry class at UCLA, I learned about THD’s promising effects on melanin production. In addition to not being intrusive, what stood out was its stability—it was efficient down to the last drop, ensuring that you can get the most out of their investment.
This sparked my THD journey, and within two years, I developed one vitamin C serum using this ingredient. The results during testing were incredible and when I released it and recommended it to clients, over the course of weeks and months the sun spots, brown spots and breakout marks improved much faster. I phased out the hydroquinone serum to use the THD ascorbate, which I found to be much more effective at brightening the skin.
What percentage of ascorbic THD is effective?
It’s less about looking at the ingredient list (known as the INCI list) and more about the type of product that uses it. Because THD Ascorbate takes time to penetrate the skin, it is best used in leave-on products. I don’t recommend it in products that wash off the skin because there just isn’t time for the THD to get to work. Also, THD requires much lower usage levels than ascorbic acid, thanks to its superior ability to penetrate the skin. Consumers often like to see higher percentages of ingredients, but more is not always more! The skin does not need as much THD as ascorbic acid to reap its benefits. For example, there is a study showing the collagen boosting effects of THD at just 0.1%. For skin glow, there are benefits seen at just 0.5%.
Here’s how to read an ingredient label.
Honestly, it’s less about the INCI list and more about the type of product that uses it. Because THD Ascorbate takes time to penetrate the skin, it is best used in leave-on products. I don’t recommend it in products that wash off the skin because there just isn’t time for the THD to get to work. Also, THD requires much lower usage levels than ascorbic acid, thanks to its superior ability to penetrate the skin. I understand how consumers like to see higher percentages of ingredients, but let me tell you, more is not always more. (Much of what social media is trying to tell you!) Skin doesn’t need as much THD as ascorbic acid to reap its benefits. For example, there is a study showing the collagen boosting effects of THD at just 0.1%. For skin glow, there are benefits seen at just 0.5%.
Is there scientific research showing how THD can help improve discoloration?
Behind the science: The main manufacturer of THD has conducted hundreds of studies on the benefits of THD, with which it was able to achieve quasi-drug status in Japan and Korea at 3% and 2%, respectively. Unfortunately, these studies are not publicly available, but there are peer-reviewed studies on the skin benefits of THD, both alone and in combination with other skin-lightening ingredients.
How often should I use vitamin C serum?
The benefits of using a vitamin C serum are when used daily as part of your morning routine. Not only does it help suppress melanin production, but using all types of vitamin C helps protect skin cells from environmental damage. It scavenges free radicals, which are unstable molecules that lead to skin damage and accelerate skin aging. Free radicals are constantly attacking us from so many different sources, including UV light from the sun, ozone, smoke, and pollution (to name a few). All of these are also responsible for a natural depletion of vitamin C in our skin over time, which is why supplementing with an oral antioxidant product is so important.
Bonus: Vitamin C helps prevent collagen breakdown and promotes healthier collagen production. First, it helps protect the collagen you already have by inhibiting a group of enzymes that break down collagen. Second, it helps promote healthier collagen production by being a cofactor for two enzymes needed to create and cross-link collagen.
When in my routine should I use a vitamin C serum?
Always in the morning. Here’s how I like to use it: after cleansing and toning my skin, I’ll use two pumps Vitamin C + E treatment and gently press it into my skin with my fingers, really letting it stick to the skin for about a minute. This gives the powerhouse ingredients a moment to do their thing before I move on to my next step.
After that, I finish with my favorite that doesn’t clog pores SPF 30 weightless protectionlocking everything in and protecting my skin from those pesky free radicals. It’s a simple yet highly effective combination that leaves my skin feeling fresh, nourished and ready to take on the day!
Bottom line for THD Ascorbate: It’s an ingredient that I really appreciate because of the research and unlike modern ingredients, this one has staying power because it’s one of those ingredients where you can actually see the difference, which isn’t the case with many ingredients even though they’re still beneficial.
Since THD is the most stable form of vitamin C and is now considered “the gold standard of vitamin C,” it doesn’t need such a low pH to be effective, which is great news for our skin barrier. I hope you’ll consider trying Vitamin C + E treatment as I have formulated it with a pH of 5.3, making it much gentler on the skin than most.
From my hands to your face, your skin barrier will thank you!
Did you know that these five ingredients can help restore your skin’s barrier?
Celebrity Esthetician & Skin Care Specialist
As an esthetician trained in cosmetic chemistry, Renée Rouleau has spent 35 years researching skin, educating her audience and building an award-winning line of products. Her hands-on experience as an esthetician and trusted skin care expert has created a real solution — products designed to nine different skin types so your face will have exactly what it needs to look and feel its best. Trusted by celebrities, editors, bloggers, and skincare enthusiasts around the world, her vast real-world knowledge and constant research is why Marie Claire calls her “the most passionate skin professional we know.”
