Citric acid is a weak organic acid. It occurs naturally in produce, and in particular, citrus fruits such as limes, oranges, and lemons.

citrus fruit, like lime, is high in citric acidShare on Pinterest
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Citric acid is a naturally occurring antioxidant. People use it as a food flavoring and preservative, an ingredient in cosmetics, and a component in cleaning products.

Because citric acid works as an additive, there is a manufactured version of it. Some people may be allergic or intolerant to this form, potentially leading to digestive issues and inflammatory responses.

Read more to learn about the natural and artificial sources of citric acid, as well as their potential benefits and risks.

Citric acid is a weak acid. In its natural form, it looks like small, clear crystals, similar to table salt. Although it is odorless, it has an acidic taste.

It is an alpha-hydroxy acid (AHA). This means it has one hydroxyl group attached to the alpha position of the acid. Other AHAs include lactic acid, glycolic acid, malic acid, and tartaric acid.

Manufacturers frequently use citric acid in many prepared foods, beverages, and vitamins. In addition to providing flavor, it also acts as a preservative.

There are both natural and artificial sources of citric acid.

Natural sources

Citrus fruits such as lemons and limes have the highest quantities of naturally occurring citric acid, according to research from 2014.

Other natural sources include tangerines, oranges, grapefruits, pineapples, tomatoes, broccoli, carrots, and berries.

Artificial sources

People often use citric acid in processed food and household products. Because of this, scientists developed a synthetic form of it using the fungus Aspergillus niger, or black mold. It is known as manufactured citric acid (MCA).

MCA is one of the most common food additives. In addition, it is used in the pharmaceutical and cosmetic industries and in cleaning detergents and softening agents.

While MCA has the same chemical formula as naturally occurring citric acid, it can contain remnants of black mold. This can trigger allergies or unwanted effects when consumed.

Citric acid is a common additive because of its many benefits and minimal environmental impact. The three main industries that use citric acid are food, cosmetics, and cleaning products.

Food

Citric acid acts as a preservative in many processed foods, keeping them fresh. It does this by slowing or helping prevent the formation of bacteria, mold, yeast, and fungus.

It retains a food’s color, flavor, and texture. This delays how quickly food spoils, increasing its shelf life.

Additionally, it can help balance the pH level, or acidity, of a food or beverage. For example, when manufacturers add citric acid to wine, it improves low acidity and taste.

Cosmetics

Citric acid provides many benefits when added to skincare products. It can brighten skin, minimize fine lines, and even skin tone.

Manufacturers also use citric acid as an additive in hairspray, deodorant, and body spray. It preserves cosmetics and personal care products to ensure they do not grow mold, bacteria, or fungus.

Cleaning supplies

Because citric acid is effective at killing harmful bacteria, it is a beneficial addition to cleaning products. It also has brightening properties that are useful for stain removal.

Citric acid has various health and skin benefits.

Evens skin tone

Manufacturers commonly use alpha-hydroxy acids (AHAs) in skin care products because of their resurfacing properties. As citric acid is a common form of AHA, it can benefit the skin.

AHAs remove the top layer of skin, revealing a new layer underneath.

Individuals with dark spots, hyperpigmentation, or scars may find citric acid particularly beneficial. Dark spots are areas of skin with higher amounts of melanin, and scars are areas of collagen fibers that form scar tissue. The scar tissue has a different texture and appearance than the rest of the skin.

When used on the skin, AHAs peel small layers of the skin away. Over time, this can remove all hyperpigmentation and scarring, leaving behind skin with a more even tone.

Minimizes fine lines

AHAs can also minimize fine facial lines.

As a person ages, the collagen and elastin in the skin break down. As a result, skin does not bounce back the way it used to, resulting in fine lines and wrinkles. They usually emerge in places where the skin moves a lot, such as around the eyes and forehead.

AHAs increase the synthesis of glycosaminoglycans, a type of complex carbohydrate that plays a role in cell hydration and communication. They also thicken the skin, which helps prevent new fine lines from appearing.

Learn more about AHAs.

Kills bacteria and viruses

Citric acid has a pH level of between 3–6. This means it is a relatively weak acid. The pH scale spans 0–14, with 7 being neutral. Items that are 0 are very acidic (such as battery acid), and those that are 14 are very basic (such as liquid drain cleaner).

In cleaning products, citric acid kills any bacteria or virus that cannot survive at its pH of 3–6.

It can also help prevent viruses such as the human norovirus, commonly known as the winter vomiting bug, from passing between people. By binding to receptors where the virus usually attaches, it prevents it from taking hold. This helps prevent transmission and reduces the worsening of a norovirus infection.

Much of the citric acid used in commercial products is MCA, which comes from the fungus Aspergillus niger.

This fungus, also known as black mold, is a known allergen.

This does not mean that MCA is black mold, and most people will have no adverse reactions to it. But if someone has a genetic predisposition to a black mold allergy, ingestion of MCA may lead to harmful inflammatory responses. These could include joint pain, muscle pain, and digestive issues.

Additionally, both natural and synthetic citric acid can harm teeth. Ingesting a sizeable amount of citric acid may damage tooth enamel over time.

After eating or drinking products high in citric acid, a person should rinse their mouth to protect their teeth.

People using citric acid in skin care should also be careful, as high concentrations applied to the skin may cause irritation.

Citric acid can increase the skin’s sensitivity to UVB radiation, leaving a person vulnerable to skin damage. People using citric acid (often called “vitamin C” products) should do so in the evening before bed, or apply SPF before going outside.

Citric acid is a naturally occurring acid with a pH of 3–6. Manufacturers use a synthetic form of citric acid, called MCA, in many commercial products. This is created from black mold and can cause allergic reactions in some people.

Manufacturers also use this versatile acid in food preservation. Although it is generally safe to use, people with sensitive skin or allergies may wish to avoid citric acid or use it in small quantities.