Citric acid is a food additive found in soft drinks, candy and canned vegetables and fruit. It is also used in cleaning products, such as air fresheners, detergents and glass cleaners. It is added to cleaning products to give them a citrus scent and to foods as a preservative.
Citric acid preserves food by lowering its pH and inhibiting bacterial growth. It is also used to add a sour citrus flavor to foods. Citric acid occurs naturally in citrus fruits, but commercially-used forms of the chemical are not extracted from fruits. Instead, they are produced by bacteria and purified for use in food and cleaning products.
Most living organisms synthesize citric acid in the form of citrate. Citrate is a vital component of metabolism in organisms that consume food for energy. Without it, cells cannot turn fats, proteins and carbohydrates into usable energy. Citrate is also an essential part of bone.
While rare, it is possible for a person to be allergic to citric acid. Because the most common dietary source of this allergy is citrus fruit, an allergy test is required to confirm a citric acid allergy. This is due to the presence of other allergens in citrus fruits. Patients diagnosed with a citric acid allergy should avoid citrus fruits and products with added citric acid.