Some fruit juice brands claim to have high amounts of antioxidants in their juices while using sodium benzoate as a preservative. While those antioxidants help to protect human cells from the damage done by free radicals (molecules responsible for aging, tissue damage, and other diseases), sodium benzoate (in conjunction with the fruits' vitamin C) does the exact opposite. It creates Benzene that damages human cells and creates various health risks. The risks include inflammation processes that eventually lead to damaging DNA and cell processes, degenerative diseases, etc.
Sodium Benzoate is on the list of unacceptable ingredients for food in Whole Foods Markets http://www.wholefoodsmarket.com/products/unacceptable-ingredients.php
Excerpt from http://www.health-report.co.uk/benzene.htm:
"ALL moist or liquid processed foods have chemicals in them for preservation. These preservatives when combined with vitamin C (ascorbic acid) may damage your health permanently"