About 80 percent of sun damage occurs before the age of 20, according to Ariel Ostad, M.D., an assistant clinical professor of dermatology at New York University Medical Center. That’s why products with free-radical fighters (from alpha lipoic acid to vitamin C), are necessities as we get older. They help fight the damage done, by slowing the oxidation process that causes sun spots and wrinkles, and preventing further damage, such as collagen and elastin breakdown. These free-radical fighters also work chemically in the deeper layers of skin to help it endure and recover from sun exposure.