Sodium benzoate is the ubiquitous preservative also known as E211. Sodium benzoate is an “almost natural” preservative made by neutralizing benzoic acid, a naturally occurring preservative that is found in apples, cranberries, plums, and prunes, with sodium hydroxide, which is also known as lye. Benzoic acid as it is found in fruit is actually a better preservative than sodium benzoate, but benzoic acid does not dissolve in water. Sodium benzoate can be easily added to beverages or liquid mixes used to make other foods.
Where will you encounter sodium benzoate? At least with regard to food and drink, it would be easier to state where you won't. Most packaged food products contain sodium benzoate. It “neutralizes” microorganisms by making the contents of their cells acidic, having the same effects as you may have heard about from the many articles and books about the “acid danger” of high-protein diets in humans. Bacteria and other microbes don't die, but their metabolism of sugar becomes so slow that they essentially go dormant. Of course, they can spring to life when you consume them, but your stomach acid and your immune system can fight them off.
What's not to love about sodium benzoate? The major issue with sodium benzoate is that it can react with vitamin C to produce a toxic chemical known as benzene (the chemical, not the auto fuel). This means that adding sodium benzoate to fruit and vegetable juices reduces bacterial growth at the expense of vitamin C content. The benzene released by the interaction of sodium benzoate and vitamin C is considered “safe,” but the amount of benzene released in an 8-ounce (240 ml) glass of juice preserved with sodium benzoate is about the same as to which you would be exposed while fueling your vehicle or a day's exposure to passive cigarette smoke.
The more acidic the juice, the less effective sodium benzoate is as a preservative. More sodium benzoate is added to acidic juices than to neutral juices. This reduces bacterial activity but destroys vitamin C, especially in orange juice. By the time you buy a bottle of orange juice, much of its original vitamin C may be destroyed by the preservatives added to the juice.
There are also issues for people who are aspirin sensitive. Sodium benzoate and the red and yellow “azo” dyes (Allura Red AC, Ponceau Red 4R, tartrazine, and others) have an additive effect with aspirin and naturally occurring chemicals in food that are similar to aspirin. If you have an aspirin allergy, sodium benzoate will make it worse, especially if you consume naturally occurring aspirin-like compounds in dried apples, prunes, dried cranberries, dill, turmeric, wintergreen, or peppermint, or if you consume drinks or foods containing coloring agents. You might break out in hives, or you might have a problem with wheezing or sneezing or even anaphylaxis that closes the throat.
Most people don't have these issues with sodium benzoate. Only about 1 in 300 people does. If you are in that 1 in 300, however, your rude awakening to the reality of your aspirin allergies might involve a scary trip to the emergency room, and is that really something on your bucket list?
There is a simple way to avoid sodium benzoate in fruit and vegetable juices. Drink fresh juice, preferably juice you make at home. Even a simple juice extractor may be what you need to make flavorful juices that won't last long enough for anyone to need to worry about their going bad.