Supplementing the diet with vitamins, minerals, and enzymes may support healthier-looking skin, and these same compounds may also work wonders from the top down, protecting against the formation of destructive molecules known as free radicals.

Alpha-lipoic acid is often called the “universal antioxidant,” because it’s soluble in both fat and water. It’s naturally made by the body and used to fight free radicals. When applied topically, ALA has been shown to penetrate skin cells, where it may decrease inflammation and boost energy production within the cells.

Biotin is water-soluble, and part of the B-complex vitamins. The body uses biotin in the metabolism of fatty acids, glucose, and amino acids. In other words, it needs biotin to turn food into fuel, and without enough, hair and nails can become weak or brittle. Similarly, adding biotin to skincare products is thought by manufacturers to help improve the health and strength of skin cells.

B-complex vitamins contain biotin, which as discussed above, is essential for healthy skin, hair, and nails. Niacin is another component of the B complex, which may improve the look of skin by increasing moisture and reducing inflammation.

Co-enzyme Q10 is a powerful antioxidant produced in the body and used to fight free radicals within cells. Since the body produces less CoQ10 with age, skin cells become more vulnerable to damage over time. Manufacturers claim that skincare products containing CoQ10 work to protect the skin’s outer layer from oxidation and aging.

Hyaluronic acid is found in skin cells, joint fluid, and connective tissue, where it works to keep everything cushioned and lubricated. Factors such as diet, lifestyle, and age can decrease how much your body produces over time. When used as a skincare ingredient, hyaluronic acid is thought by manufacturers to help smooth and even the complexion.

Vitamin A is essential for healthy skin and eyes. When taken into the body via foods like butter and eggs, it’s converted into retinoic acid, which binds to receptors in the skin, keeping them healthy and plump. Makers of topical vitamin A claim it contributes to thickening the skin and keeping it firm.

Vitamin C is likely the most well-known antioxidant. It helps fight free-radical damage and also plays a roll in collagen production. As a topical agent, vitamin C may increase skin density and decrease the appearance of aging.

Vitamin E is a fat-soluble antioxidant that is essential for the maintenance of healthy skin. Naturally provided to skin cells via sebum, vitamin E can absorb the energy from UV light, protecting the skin from sun damage. When used in skincare products, vitamin E works to both protect the skin and improve its texture.

Vitamin K is one of the lesser-known vitamins, but it’s beginning to make a name for itself in the world of skincare. In the body, vitamin K is essential for proper blood clotting, but when used topically, it has been associated with lightening dark circles and bruises.