Vitamin C (THD Ascorbate)

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There seems to be a new vitamin C skincare product on the shelves every day, and with good reason: Dermatologists, scientists, and beauty experts all agree that it's a powerful ingredient that can make skin brighter and clearer. But that's only the case if enough vitamin C can be absorbed into your skin before it breaks down. One newer form of vitamin C, tetrahexyldecyl ascorbate (or THD ascorbate), is the key to really making that happen.

The body typically uses the vitamin C that we get from our diet to build collagen, ligaments, skin, blood cells, and other essential tissues. Vitamin C is also important for repairing bones, skin, teeth, and cartilage, and it helps us absorb iron. Plus, vitamin C is an important antioxidant that can protect many systems in the body from the damage done by the sun, pollution, smoking, and more. 

Though there are constant studies being done—often with conflicting results—about whether taking vitamin C supplements can cure the common cold or even prevent heart disease, there is one thing healthcare providers and scientists do agree on: The best source of vitamin C is fruits and vegetables that are high in the vitamin, such as citrus fruits, berries, broccoli, bell peppers, and spinach. Since vitamin C is water-soluble, the body can't store it, so we need to keep consuming it regularly. But while it's a great idea to keep up that healthy diet, we now also have the option to bypass the stomach and deliver vitamin C to the skin directly.

The Best Vitamin C Serum: THD Ascorbate Vs. L-Ascorbic Acid

L-ascorbic acid is the form of vitamin C that our bodies use. This is why you will see it touted as the best form of vitamin C to look for in skincare ingredients. But this is only half true: The problem with L-ascorbic acid, also referred to simply as ascorbic acid, is that it is not a stable compound. When exposed to light, air, or heat, it degrades quite quickly in bottles and tubes, meaning that you might buy a serum that says it has a high concentration of vitamin C (anything under 20% is recommended) but by the time you actually apply it to your skin, you have much less than that... and once the bottle has been open for a few weeks, even less. This is why scientists and product developers have been trying to come up with a more stable form of vitamin C to use in cosmetics.  Enter THD ascorbate.

THD ascorbate is lipid-soluble (it dissolves in oil or fat cells), and much more stable than ascorbic acid. That lipid formulation also helps it penetrate into the deeper layers of the skin. This is because the skin's barrier, the stratum corneum, is made up of skin cells held together by lipids, and lipid-soluble ingredients can move through those lipids more easily than water-soluble ingredients. This oil formulation may also be gentler on the skin that ascorbic acid.

Once you apply THD ascorbate topically, the body breaks it down into ascorbic acid, then uses it for all the things vitamin C can do for the skin.

Vitamin C for Sun Damage

Vitamin C is one of the most common antioxidants found in the skin, and it is essential to making sure the sun and other external factors don't damage skin cells. Here's a refresher on how antioxidants work: UV radiation, smoke, pollution, and also just the very act of breathing can change oxygen molecules in the body to free radicals. Free radical molecules have an extra electron, which makes them try to bind to other nearby molecules to steal electrons, and in the process, they cause a chain reaction that damages cells. This damage shows up in the form of decreased collagen (causing fine lines and loss of elasticity), dark spots, and inflammation. Antioxidants help by cleaning up those free radicals and neutralizing them, instead of letting them ravage the important cells in the body. 

When you apply extra vitamin C to the skin, it's like sending in reinforcements to guard your cells. Studies have also shown that topical vitamin C is even more effective at protecting skin when it's combined with another antioxidant, vitamin E.

Vitamin C for Skin Brightening

If the sun has already begun to damage skin by causing hyperpigmentation, or dark spots, vitamin C works to brighten that skin as well. It does so by stopping an enzyme called tyrosinase from forming melanin, the pigment that causes these dark spots. 

Vitamin C for Softer, Smoother Skin

A vitamin C serum with THD ascorbate can have rejuvenating benefits for skin because the body relies on vitamin C to trigger collagen production. Collagen is the protein that holds up the skin's structure, and the skin naturally produces less of it with age. Boosting collagen restores the natural elasticity we associate with younger, healthy skin.

Vitamin C also helps repair damaged DNA in skin cells and promotes the creation of lipids in the skin barrier. That means it helps wounds heal and strengthens that barrier to lock in moisture and stop skin from drying out.

Vitamin C for Acne and More

Inflammation is one of the body's immune responses to injury and infection, but it can also be an overreaction that causes such conditions as acne and rosacea. Vitamin C serum helps acne and rosacea by blocking the process that starts inflammation in the skin. 

There is little doubt that vitamin C is very useful for a number of functions in the body. The key to making it work best is helping it reach the cells it needs to. That's why many experts recommend vitamin C serums using THD ascorbate to protect, repair, brighten, and soften all types of skin.

Next Up: Vitamin E