Citric acid, a prominent ingredient in fruits, processed foods and some medicines, may cause stomach upset or other health problems in some people who cannot tolerate the substance or possibly have allergic reactions to it. In some cases, however, medications containing citric acid can actually relieve stomach complaints.
Citric acid occurs naturally in the human body. Citrus fruits and fruit juices provide generous amounts of dietary citric acid, with lemon and lime juice possessing higher levels of it than grapefruit or orange juice. Vegetables, roots and milk may also contain citric acid. Modern industrial technology can produce citric acid from molasses, adding it to products for flavoring, preservation or pharmaceutical use.
Some people have an allergic reaction to citrus fruits. In a food allergy, the body interprets a substance in the food as an invader and mounts an attack against it. The immune system produces antibodies and other chemicals during the allergic reaction, including histamine, a substance which produces a runny nose, itching and other familiar allergy symptoms. Severe allergic reactions can cause nausea, diarrhea and even death. While people may claim to be allergic to citric acid specifically, they may in fact suffer reactions to a chemical called limonene, or to proteins in the fruit, and not to the citric acid itself.
A rare ailment known as citric acid intolerance can cause illness. An intolerance differs from an allergy in that, instead of having an immune-system reaction to the food in question, the body simply cannot digest it due the lack of an essential chemical that breaks that food down. Symptoms of citric acid intolerance include stomach pain and cramping, diarrhea, vomiting, blotchy or scabby skin and dark rings under the eyes.
As irritating as citric acid may prove to some stomachs, it may cure an upset stomach in others. One such situation involves an irritating condition called acid reflux disease, also known as gastroesophageal reflux disease (GERD). While GERD stems from acid rising to the throat, unusually low stomach-acid levels may actually worsen the condition as the undigested food sits in the stomach. Citric acid medication seems to provide relief in such cases. Alka-seltzer, a popular over-the-counter medicine, combines citric acid, aspirin and hydrogen carbonate to ease indigestion and headache. Ulcer patients, however, must avoid Alka-seltzer because of the risk of aggravating their condition.
The best way to prevent stomach trouble from citric acid is to avoid foods that contain it, including foods that include it as an additive. Check the lists of ingredients on food labels to see whether a food contains added citric acid. Fruits with relatively little citric acid include apples, pears, cherries, grapes and dried figs. Multivitamins and omega-3 oils such as flaxseed or cod liver oil may ease the effects of citric acid on the stomach.