Nitrates, nitrites and sulpher dioxide (sulfur dioxide) are preservatives added to food to protect against harmful bacteria which can cause food poisoning and spoilage. They can also increase the storage life of foods.
Nitrates and nitrites, in particular sodium nitrite, are used for the curing of meat (e.g. bacon, ham and gammon) because they prevent bacterial growth and react with the meat protein giving the product a desirable dark red color. Because of the toxicity of nitrite (the lethal dose of nitrite for humans is about 22 mg per kg body weight), the maximum allowed nitrite concentration in meat products is 200 ppm. Under certain conditions, especially during cooking, nitrites in meat can react with degradation products of amino acids, forming nitrosamines, which are known carcinogens.
Sulpher dioxide is sometimes used as a preservative for dried fruits due to its antimicrobial properties. It maintains the appearance of the fruit and prevents rotting, and can give fruit a distinctive chemical taste. It is also used in the making of wine and some other alcoholic drinks, and wine making sanitation to prevent degredation and microbial damage.
Check ingredient lists for the following:
- E220 - Sulphur dioxid
- E221 - Sodium sulphite
- E222 - Sodium hydrogen sulphite/sodium bisulphite
- E223 - Sodium metabisulphite
- E224 - Sodium metabisulphide
- E226 - Calcium sulphite
- E227 - Calcium hydrogen sulphite/calcium bisulphite
- E228 - Potassium bisulphite
- E249 - Potassium nitrite
- E250 - Sodium nitrite
- E251 - Sodium nitrate
- E252 - Potassium nitrate
Food sources of benzoates
- Dried fruit, dehydrated vegetables
- Fruit juices
- Fruit based desserts
- Wine, beer, cider
- Bacon, ham, cured meats, corned beef, gammon steak
- Some cheese
Not all of the above will contain nitrates, nitrites or sulpher dioxide, but definitely check these foods. Look out for products that state they are 'free from preservatives', but if in doubt, avoid.
Adhering to a healthy diet, avoiding processed and manufactured foods is the simplest way to avoid added preservatives. The following example meal plan has been designed to eliminate nitrates, nitrites, sulpher dioxide and other artificial preservatives from their diet. It's based on an average weight individual with a sedentary job for weight maintenance. Use this to give you an idea of what are healthy nutritious foods to include, but don't forget to vary your food choices and to drink plenty of water through the day.