What Do Antioxidants Do in Skincare?

In one small study, researchers applied a solution of vitamins C and E to patches of people's skin, then exposed the skin to a controlled dose of UV light. Compared with patches that hadn't received the antioxidants, the treated patches showed less redness and fewer sunburn cells, skin cells damaged by the UV.⁷ That's a measurable result from something applied like a serum. Antioxidants limit chemical reactions that can damage cells. In skincare, researchers study them for protection against environmental stress such as UV exposure, and for changes in the visible signs of aging.^{1, 2}

But "antioxidant" covers several different jobs, because each ingredient brings its own chemistry. Vitamins C and E are both antioxidants, for example, and vitamin C also helps the body make collagen.² So when a product makes an antioxidant claim, it helps to know which job the ingredient is doing, whether the formula lets it do that job, and what was actually measured.

Your skin already has antioxidant defenses

Oxidation can change molecules, including the fats and proteins your cells depend on, much as it turns cooking oil rancid. Some of the molecules driving it are free radicals, which react readily with other molecules, a bit like sparks that set off more sparks. Your body makes reactive molecules during normal metabolism, and sunlight and air pollution can add more.¹

Not all of that activity is harmful, since some reactive molecules help cells communicate. Oxidative stress is what happens when the activity overwhelms the body's defenses.¹

Vitamin E is one of the defenses. It helps protect fats from oxidation, and in a small study, researchers found it in sebum, the oil released by the skin's sebaceous glands.³ So the oil on your skin's surface carries part of its own antioxidant defense. Antioxidant skincare adds ingredients to those defenses, to help manage reactive molecules when there are more than the skin can handle.¹

Different antioxidants do different jobs

Some antioxidants support each other. When vitamin E acts as an antioxidant, it can become oxidized itself, and vitamin C, in the form of L-ascorbic acid, can help return it to its active form.² Think of vitamin C as recharging vitamin E so it can keep working.

Antioxidants can also protect the other ingredients inside the product. In a study of a solution containing vitamins C and E, adding ferulic acid made the vitamins more chemically stable.⁴ So even antioxidants can need antioxidants, and keeping ingredients intact before and during use is one reason a formulator might combine them.

The form an ingredient comes in matters too. Tetrahexyldecyl ascorbate, often shortened to THD ascorbate, is an oil-soluble precursor of vitamin C, with fatty groups attached to the ascorbic acid molecule. The groups have to come off before it works as vitamin C. In a lab experiment, an enzyme found in skin cells removed them and released ascorbic acid, which shows the conversion can happen under lab conditions. How much converts in human skin is still a separate question.⁹

Recharging, protecting the formula and converting are different jobs, and the benefit being investigated decides what needs to be measured.

Does the formula change where an ingredient goes?

An ingredient has to get out of the formula around it, which researchers call the vehicle, and reach the place where it's meant to act. Research on topical L-ascorbic acid has shown that how well it gets into skin depends on how it's formulated.⁶

In one experiment, researchers put vitamin E into emulsions, mixtures of tiny oil droplets in water, and applied them to samples of pig-ear skin. They varied the balance of coconut oil and squalane in the droplets. The emulsion whose oil was all squalane put the most vitamin E into the fluid beneath the skin sample. A blend of two parts coconut oil to one part squalane left the most vitamin E within the skin itself.⁵

The two results can look like they compete, but they answer different questions. The amount in the fluid shows how much vitamin E passed all the way through the skin, and the amount left in the skin shows how much stayed. For an ingredient meant to act within skin, what stays is the part to watch.

What have studies found in people?

In the UV study, the solution went on the skin for four days before the UV exposure, and it also contained ferulic acid. The comparison patches got the vehicle alone, and less redness and fewer sunburn cells were only some of the protective findings.⁷

A second study ran for six months on skin that was already sun-damaged. Researchers compared a vitamin C cream with the same cream base without it, on women's lower necks and arms. The vitamin C cream improved overall clinical ratings and measures of skin surface texture.⁸

Studies in people can look at protection during an exposure, as the UV study did, or at change over months of use, as the cream study did. Either way, the findings don't automatically carry over to other formulas or conditions. And since vitamin C also contributes to collagen production, the cream's results can involve more than antioxidant activity. The trial measured the overall result without isolating how much each mechanism contributed.^{2, 8}

Can an antioxidant serum replace sunscreen?

No. An antioxidant serum doesn't replace sunscreen. The American Academy of Dermatology recommends broad-spectrum, water-resistant sunscreen with SPF 30 or higher, along with shade and protective clothing.¹⁰ Antioxidant skincare plays a complementary role. The researchers behind the UV study described their approach as working differently from sunscreen, in a way that could add to sunscreen's protection.⁷

How to read an antioxidant claim

Start with the ingredient and the form it's in. L-ascorbic acid and THD ascorbate have different chemical structures, so if you're comparing two vitamin C serums, keep their research apart.

Then look at the benefit being claimed and the kind of test behind it. A stability experiment tells you how well ingredients stay intact in a formula, and a delivery experiment tells you where an ingredient goes. A texture trial in people tells you about a change in appearance. Whatever the test, look for what was tested, what it was compared with and what changed. A finding from a particular cream doesn't automatically apply to other products with the same ingredient.

In Omnia, antioxidants are part of a waterless, moisturizing formula. Squalane and jojoba esters make up its emollient base, alongside the vitamin C precursor THD ascorbate and vitamin E tocopherols. THD ascorbate dissolves in oil, which suits it to a waterless format, and vitamin E helps protect lipids from oxidation.^{1, 9} The formula brings together ingredients chosen for antioxidant support and soft, supple-feeling skin.

The next time a product promises antioxidant benefits, start by asking which job the antioxidant is there to do.

Sources

1. National Institutes of Health, Office of Dietary Supplements. Vitamin E: Fact Sheet for Health Professionals. Accessed October 12, 2026.
2. National Institutes of Health, Office of Dietary Supplements. Vitamin C: Fact Sheet for Health Professionals. Accessed October 12, 2026.
3. Thiele JJ, et al. Sebaceous gland secretion is a major physiologic route of vitamin E delivery to skin. Journal of Investigative Dermatology, 1999.
4. Lin FH, et al. Ferulic Acid Stabilizes a Solution of Vitamins C and E and Doubles its Photoprotection of Skin. Journal of Investigative Dermatology, 2005.
5. de Souza AC, et al. Effect of Squalane as a Carrier in O/W Nanoemulsions for Dermal Delivery of Vitamin E. ACS Omega, 2025.
6. Pinnell SR, et al. Topical L-ascorbic acid: percutaneous absorption studies. Dermatologic Surgery, 2001.
7. Murray JC, et al. A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid provides protection for human skin against damage caused by ultraviolet irradiation. Journal of the American Academy of Dermatology, 2008.
8. Humbert PG, et al. Topical ascorbic acid on photoaged skin. Clinical, topographical and ultrastructural evaluation: double-blind study vs. placebo. Experimental Dermatology, 2003.
9. Swindell WR, et al. Tetrahexyldecyl Ascorbate (THDC) Degrades Rapidly under Oxidative Stress but Can Be Stabilized by Acetyl Zingerone to Enhance Collagen Production and Antioxidant Effects. International Journal of Molecular Sciences, 2021.
10. American Academy of Dermatology. Sunscreen FAQs. Accessed October 12, 2026.