Antioxidants are nutritional supplements. They help neutralize free radicals formed in the body. Free radicals are oxygen byproducts that can have both toxic and swelling effects on different body tissues. Antioxidant therapy, including Vitamin E and beta carotene, has been recommended to prevent these effects. Taking a daily multivitamin with Vitamin E and beta carotene may help in the treatment and prevention of sinusitis. Large doses of Vitamin E and/or beta carotene, however, have not been effective. Fresh fruits and vegetables contain antioxidants and some products have been formulated to optimize on the antioxidant contents of some fruits and vegetables. These products are currently being studied for their anti-inflammatory effects in upper and lower respiratory allergic conditions.