Sodium benzoate occurs naturally in some fruits but is used in far higher concentrations to stop fizzy drinks from going moldy. In an Independent on Sunday exclusive last May, Professor Peter Piper, a chemistry expert at Sheffield University, warned that it could switch off cellular power in yeast and might do similar damage in humans. He called for the Food Standards Agency to fund research into the subject.
Sodium benzoate was also one of seven E-numbers found to worsen hyperactivity in a study by Southampton University. If combined with vitamin A, sodium benzoate can form a potentially carcinogenic substance, benzene. Coca-Cola said it had removed sodium benzoate from Diet Coke production in January.