Citric acid is a natural component of fruits and fruit juices, with the largest amounts being in citrus fruits. In fact, it's what gives lemons and limes their characteristic sour flavor. Lemons and limes contain the most citric acid, but oranges, grapefruits and other citrus fruits -- and even berries -- contain large amounts as well.
Citric Acid as a Food Additive
Citric acid is used both as a natural flavor enhancer and preservative in a variety of foods, such as jams and jellies, and canned fruits and vegetables. It's also used in ice cream, fruit drinks, candy, and carbonated beverages. It helps to regulate acidity, functions as an antioxidant and helps retain color.
The citric acid used in foods is made by a bacteria called Aspergillus niger. It was first produced in England from lemons in the early 1800's. Lemon juice was the main source of citric acid until 1919, when the first industrial process using A. niger began in Belgium. Today, most citric acid is produced in Mexico and Africa.
Citric Acid Safety
The United States Food and Drug Administration considers citric acid to be safe for use as a food additive. It appears that all of the citric acid that you consume is completely metabolized in your body -- there's no toxic build up and it's not stored.
But there are some anecdotal reports of people who are sensitive to foods that contain citric acid. It's difficult to determine an actual citric acid allergy because it's found in, or added to, so many different foods.
On average, the amount of citric acid added to food products by the manufacturers is about 500 milligrams per person per day, which is equal to the amount found in two ounces of orange juice. It's not enough to change the citric acid levels in your body.
Wait, what? That's right -- you already have citric acid in your body right now because it's a normal component of cellular metabolism. In fact, the citric acid cycle is the metabolic pathway by which foods are broken down into water, carbon dioxide and energy.
Citric acid and it's close relative, citrate is also used as an inactive ingredient in certain medications and dietary supplements. But it may have some health benefits -- citric acid slows kidney stone formation. The more citric acid you have in your urine, the less likely you are to form kidney stones.
Center for Science in the Public Interest. "Chemical Cuisine -- Learn about Food Additives." Accessed July 9, 2014. http://www.cspinet.org/reports/chemcuisine.htm.
CODEX Genera Standard for Food Additives Online Database. "Food Additive Details." Accessed July 9, 2014. http://www.codexalimentarius.net/gsfaonline/additives/details.html.
Max B, Salgado JM, Rodríguez N, Cortés S, Converti A, Domínguez JM. "Biotechnological production of citric acid." Braz J Microbiol. 2010 Oct;41(4):862-75.
United States Food and Drug Administration Database of Select Committee on GRAS Substances (SCOGS) Reviews"Citric acid." Accessed August 21, 2009. http://www.accessdata.fda.gov/scripts/fcn/fcnDetailNavigation.cfm?rpt=scogsListing&id=82.
University of Wisconsin Hospitals Health Information: Health Facts for You. "Kidney Health: Citric Acid and Kidney Stones." Accessed July 9, 2014. http://www.uwhealth.org/healthfacts/nutrition/353.html.