The Science Behind Antioxidants in Skincare Products
“Oxidation happens when oxygen atoms combine with other atoms, and sometimes the oxides produced in these reactions are toxic—they can interfere with the activity of cells,” explains John Kulesza, president of skincare company Young Pharmaceuticals. “Antioxidants, in general, are compounds that prevent oxidation reactions.”
But how do antioxidants address different skin concerns? Read on to learn how they can help improve your clients’ skin.
Antioxidants and Aging
In her latest textbook Cosmeceuticals and Cosmetic Ingredients (McGraw Hill, 2015), dermatologist Leslie Baumann, MD, identifies a number of antioxidants produced by our bodies, including superoxide dismutase, catalase and ascorbic acid (vitamin C)—all of which grow less active the older we get. “This leads to an imbalance and increased number of unchecked free radicals, which engender damage to DNA, cytoskeletal elements, cellular proteins and cellular membranes,” she writes. In other words, free radicals can cause the skin’s structure and strength to deteriorate.
Antioxidants are able to neutralize those free radicals, which can prevent the development of new wrinkles (rather than treat those that are already present). Dr. Baumann notes that topical antioxidants have other antiaging benefits as well. “Many antioxidants exhibit anti-inflammatory properties or depigmenting activities,” she writes. “They protect cell membranes, proteins, DNA and mitochondria.”
More Effective Sun Protection
In recent years, antioxidants have become common ingredients in sun protection products. “Sunlight, especially UV light, has a lot of energy that’s able to knock electrons o of atoms, creating reactive oxygen species—which can be damaging and lead to inflammation,” says Kulesza. “There are classic studies that show if you apply an antioxidant, like vitamin C, to the skin immediately after sun exposure, you can reduce the amount of redness that occurs.”
He adds that there is a window of time within which an antioxidant may produce the desired effect—if you wait too long after sun exposure to apply a topical antioxidant, it won’t work. Hence, adding them to sun protection products addresses this issue by minimizing the amount of reactive oxygen species that are formed during exposure while preventing sunburn at the same time. Because no SPF is perfect, topical antioxidants in sunscreens also help protect from any radiation that gets through the sun block, points out Dr. Baumann.
“SPF products should always include antioxidants to help reset any imbalance and quickly neutralize potential damage,” agrees Neal Kitchen, PhD, COO of HydroPeptide. “Formulators are finding better combinations of antioxidants and sun blockers that work synergistically to protect against damage.”
The main issue when it comes to formulating antioxidant skin care involves the very air we breathe—antioxidants are affected the moment they’re exposed to the atmosphere. “For example, we can dissolve vitamin C in a solution, but these solutions eventually oxidize—they react with oxygen in the air, turn brown and lose their potency,” observes Kulesza. “It’s the same challenge with green tea, which is a popular, very powerful antioxidant. Ferulic acid, a fascinating antioxidant material, also reacts with oxygen in the air.” Antioxidants will break down when exposed to the oxygen in a water-based solution as well. “Water is H2O, and antioxidants dissolved in aqueous media will react to it even without exposure to air,” he explains.
Formulators have found a way around these challenges via airless pumps and packaging that protect ingredients from oxidizing, and by substituting other solvents— such as glycerin, propylene glycol and polyhydric alcohols like ethoxydiglycol—in place of water to improve the antioxidants’ stability. Kulesza also points to “stabilizers— antioxidants that protect antioxidants. One reason it’s beneficial to combine ferulic acid with vitamin C is that the ferulic acid protects the vitamin C from oxidation. So it has a stabilizing effect on the formula,” he says.
Keeping antioxidants stable and bioavailable ensures that they’re able to work on the skin once applied topically; this can also be achieved by manipulating the molecules themselves. “Pure vitamin C is a very powerful antioxidant but can be quite volatile in formulations,” notes Kitchen. “Fortunately, modifications to the molecular structure can help with stability. For example, tetrahexyldecyl ascorbate is a stable form of vitamin C that is oil-soluble, which makes it an ideal ingredient for skin care.”
He adds that there are many antioxidants that defend the skin against daily damage, and combining a number of them—provided they are stabilized—will only serve to make a product more eective. “It’s common to lump all antioxidants into one group rather than seeing each one as unique. Some are better at combatting certain types of free radicals than others, so it’s really important to design formulas that blend multiple types of antioxidants for synergistic benefits,” reports Kitchen.
With research ongoing, we can expect to see some new topical antioxidant ingredients in addition to old favorites. Kulesza predicts that there will be more work with ferulic acid esters. “An ester is simply where we attach a fat to the ferulic acid, and that can actually improve the stability of ferulic acid,” he says. Formulators are also turning toward resveratrol over green tea because it poses less of a challenge in terms of penetration. “Resveratrol and green tea are phenolic compounds, which means they have a ring of six carbon atoms—phenolic compounds in general are powerful antioxidants,” says Kulesza. “But green tea is a very large molecule, and there are challenges in terms of its size, stability and ability to penetrate the skin. Resveratrol is a much smaller molecule, and it may also have some skin lightening or brightening capabilities.”
Oral and topical argan oil works well for dry and sensitive skin, says Dr. Baumann. “It has hydrating, anti-inflammatory and antioxidant properties, plus it’s high in linoleic acid, which helps the body make ceramides that hydrate and decrease inflammation,” she says. There is anecdotal evidence that it may even help soothe rosacea. “Of course ascorbic acid, green tea and resveratrol are also great—not new—but they have strong data,” adds Dr. Baumann. “My rule of thumb is to eat, drink and put on topically as many different kinds of antioxidants as you can.”
- Antioxidant-rich pomegranate and green tea extract were found to have antibacterial properties that help inhibit four common strains of bacteria associated with acne (Journal of Drugs in Dermatology, 2015).
- A serum containing L-ascorbic acid (vitamin C), alpha-tocopherol (vitamin E) and ferulic acid helped better protect subjects’ skin from sunburn and UV- related inflammation (Journal of the American Academy of Dermatology, 2017).
- A study investigating topical antioxidants revealed that a blend of resveratrol, green tea polyphenols and caeine visibly reduced participants’ facial redness (Journal of Drugs in Dermatology, 2013).
Did You Know?
The debate as to whether antioxidants can be overused is a common one. John Kulesza, president of skincare company Young Pharmaceuticals, points out that even free radicals serve a purpose and cautions that it may not be beneficial to get rid of them all. “Our bodies actually use free radicals, which cause oxidation reactions, to fight the invasion of abnormal cells,” he explains. “Say there are abnormal cells that may be turning into cancer cells; our bodies have systems to identify those cells and destroy them. They do so by creating reactive oxygen species—the things that oxidize.” There have been a number of studies investigating the benefit and harm of antioxidant supplements, but there’s still no definitive answer; though antioxidants’ beneficial properties are well established, there’s still a question as to how much is too much.
–by Laura Waldon