Colas derive their colour from caramel, which basically is a complex mixture of compounds produced when various carbohydrates such as sucrose, fructose, glucose or starches are heated to a high temperature. Put some sugar or starch in a pan, heat it, and soon you鈥檒l have caramel. And of course a mess to clean up. Chemically, caramelization is a very complex process resulting in the formation of hundreds of compounds. To complicate things further, there are several types of commercial caramelization processes, depending on what other reagents are added to the carbohydrate source as it is being pyrolyzed. Adding acids or alkalis to promote caramelization is common, but it is also possible to add sulphites such as sodium sulphite or ammonia compounds such as ammonium carbonate to achieve specific shades of brown.
Caramelization also occurs commonly in cooking and produces basically the same set of compounds as a commercial process except for when ammonium compounds are added. Any complex mixture like this will contain some compounds that when isolated and carefully investigated will produce some adverse effects in cell cultures or laboratory animals. When ammonium compounds are used, some of the breakdown products fall into the imidazole family, a couple of which, namely 4-methylimidazole and 2-methylimidazole have been shown to cause cancer in rats and mice. This can provide some gristle for the alarmist mill. And it has.
The Center for Science in the Public Interest, usually a reliable organization when it comes to nutritional issues, has overstepped the boundries of good scientific sense in its petition to the FDA to have caramel produced by the ammonium addition process banned as a food additive. It claims that the imidazoles in cola colouring could be responsible for thousands of cancers a year. What evidence is there for this? Aside from two studies using isolated imidazoles that showed carcinogenicity in rodents, none. There are all sorts of studies showing that caramel colouring itself is not carcinogenic. Numerous examples exist of mixtures that are not carcinogenic despite the presence of some carcinogens. Coffee is a classic example. No regulatory agency has listed caramel, or indeed any of its components as a carcinogen. Save one. California!
The state has proposed that 4-methylimidazole be added to the list of 鈥渃hemicals known to the state of California to cause cancer.鈥� If this listing is finalized than all cola drinks in California will have to carry a cancer warning, according to the state鈥檚 bizarre Proposition 65 which states that any product that conatins a carcinogen requires a warning label. Caramel colouring is also used in beer, bread, chips, doughnuts, ice cream, whiskey and a myriad of other items, so supposedly all these will require warnings as well. This is sheer nonsense. To equal the amount of imidazole the rats were fed over a 72 hour period, a human would have to consume roughly 12,000 bottles of cola.
European regulatory agencies do not buy into this fear-mongering. The European Food Safety Authority (EFSA), certainly not known for its laxity when it comes to evaluating safety, has carried out a reevaluation of caramel coluring and has concluded that caramel colours are not carcinogenic. EFSA has established a safe intake of caramel colouring at 300 mg per kilogram of body weight.
