When the cold and flu season strikes, a glass of orange juice is many consumers’ solution to getting their daily dose of vitamin C to help strengthen their immune systems. On average, 5 to 20 percent of the U.S. population, including normally healthy individuals, is affected by the flu each year, according to the U.S. Centers for Disease Control and Prevention. Although less severe than the flu,  most adults also come down with the common cold two to four times a year, particularly from September through May, the American Lung Association says. And because there are no antiviral medicines for treating the common cold, many consumers turn to water and juices with minerals and vitamin C as at-home remedies, it notes.

Vitamin C happens to be one of the key antioxidant vitamins, along with vitamins A and E, according to Rockville, Md.-based Packaged Facts’ March 2012 report “Antioxidant Products in the US.” Antioxidants are molecules that inhibit the oxidation of other molecules, the market research firm states. In this way, antioxidants have the ability to neutralize free radicals, which have been shown to be harmful to the body’s cells, says Phil Kupper, senior scientist for Wild Flavors USA Inc., Erlanger, Ky. “Over time, free radicals can increase in the body and generate oxidative stress,” he says. “This gradual buildup of free radicals is thought to contribute to both the aging process as well as several disease states.”