What is citric acid?
In 1784, Swedish researchers first extracted citric acid from lemon juice. This odorless and colorless compound was produced from lemon juice until the early 1900s, when researchers discovered that it could also be made from black mold (Aspergillus niger), which produces citric acid when it feeds on sugar. Due to its acidic and sour-tasting properties, citric acid is mainly used as a flavoring and preservative - especially in soft drinks and confectionery. It is also used to stabilize or preserve medications and as a disinfectant against viruses and bacteria.
Natural food sources
Citrus fruits and their juices are the best natural sources of citric acid. In fact, the word citric originates from the Latin word citrus.
Examples of citrus fruits include:
- Lemon
- Lime
- Orange
- Grapefruit
- Orange
- Grapefruit
Other fruits also contain citric acid, but in smaller amounts. These include:
- Pineapple
- Strawberry
- Raspberries
- Cranberry
- Cherry
- Tomato
Beverages or foods containing these fruits - such as ketchup from tomatoes - also contain citric acid. Although not naturally occurring, citric acid is also a byproduct of the production of cheese, wine, and sourdough bread. The citric acid listed in food and supplement ingredients is manufactured, not a naturally occurring substance found in citrus fruits. This is because it is too expensive to produce the additive from citrus fruits and demand exceeds supply.
Artificial sources and uses
The properties of citric acid make it an important additive in a variety of industries. It is estimated that 70% of artificial citric acid is used in food and beverages, 20% in pharmaceuticals and dietary supplements, and the remaining 10% in detergents.
Food Industry
Artificial citric acid is one of the most common food additives in the world. It is used to increase acidity, enhance flavor and preserve ingredients. Sodas, juices, powdered drinks, candy, frozen foods, and some dairy products often contain artificial citric acid. It is also added to canned fruits and vegetables to prevent botulism, a rare but serious disease caused by toxin-producing Clostridium botulinum bacteria.
Drugs and dietary supplements
Citric acid is an industrial staple in pharmaceuticals and dietary supplements. It is added to medications to help stabilize and preserve the active ingredients, and is used to enhance or mask the taste of chewable and syrup medications. Mineral supplements, such as magnesium and calcium, may contain citric acid - in the form of citrate - to enhance absorption.
Disinfection and cleaning
Citric acid is a useful disinfectant that fights a variety of bacteria and viruses. A test-tube study suggests it may be effective in treating or preventing human norovirus, a leading cause of foodborne illness. Citric acid is sold commercially as an all-purpose disinfectant and cleaner for removing soap scum, hard water stains, lime, and rust. It is considered a safer alternative to traditional disinfectants and cleaning products such as quaternary ammonium salts and chlorine bleach.
Health benefits and body uses
Citric acid has many impressive health benefits and functions.
Metabolic energy
Citrate—a closely related molecule of citric acid—is the first molecule formed in a process called the citric acid cycle. Also known as the tricarboxylic acid (TCA) or Krebs cycle, these chemical reactions in your body help convert food into usable energy. Humans and other living organisms derive most of their energy from this cycle.
Enhance nutrient absorption
Mineral supplements come in many forms. But not all forms are equal, as your body will use some more efficiently. Citric acid increases the bioavailability of minerals, allowing your body to absorb them better. For example, calcium citrate does not require stomach acid for absorption. It also has fewer side effects, such as gas, bloating, or constipation, than another form called calcium carbonate. Therefore, calcium citrate is a better choice for people with less stomach acid, such as the elderly. Similarly, the citrate form of magnesium is more completely absorbed and more bioavailable than magnesium oxide and magnesium sulfate. Citric acid may also enhance the absorption of zinc supplements.
Can prevent kidney stones
Citric acid — in the form of potassium citrate — prevents new kidney stones from forming and breaks down kidney stones that have already formed. Kidney stones are solid masses made of crystals that usually originate in the kidneys. Citric acid prevents kidney stones by making your urine less conducive to stone formation. Kidney stones are usually treated with citric acid as potassium citrate. However, eating foods high in this naturally occurring acid—such as citrus fruits—can provide similar stone-preventing benefits.
Safety and Risk
Manufactured citric acid is generally recognized as safe (GRAS) by the Food and Drug Administration (FDA) (5). There are no scientific studies investigating the safety of long-term consumption of large amounts of artificial citric acid. Still, there are reports of illnesses and allergic reactions caused by the additive. One report found that four people developed joint pain, swelling and stiffness, muscle and stomach pain, and shortness of breath after eating foods containing artificial citric acid. These same symptoms are not observed in people who consume natural forms of acid, such as lemons and limes. The researchers acknowledged that they could not prove that manufactured citric acid was responsible for the symptoms, but recommended further research into its use in food and beverages. In either case, scientists believe the symptoms are most likely related to the mold used to produce citric acid, rather than the compound itself.
Summary
Citric acid occurs naturally in citrus fruits, but a synthetic version—produced by a type of mold—is often added to foods, medications, supplements, and cleaners. Citric acid is generally considered safe, although mold residue from the manufacturing process may trigger allergies in rare cases.
