What Is Citric Acid, and Is It Safe?

It's the non-naturally occurring citric acid that gets some people's knickers in a twist, which is not too surprising given that it's actually grown on black mold — the same type you might find in your bathroom. Even more daunting, this version of citric acid accounts for the vast majority out there in the world.

"Today, 99 percent of citric acid is made via microbial fermentation. Only 1 percent is naturally derived from citrus fruit," says registered dietitian Erica Julson in an email interview.

To manufacture mass quantities of citric acid, which is used in a dizzying array of products (more on that in a minute), a mold called Aspergillus niger (A. niger) is grown in pans using a carbohydrate substance like sugar or molasses to help the fermentation process along. Other inorganic ingredients, like potassium phosphate and magnesium sulfate are then added, and once the ideal pH balance is achieved the sterile pans are introduced to the A. niger spores, which then germinate and eventually cover the liquid. The resulting product is a mat of mold. Several days later, the citric acid starts being produced until most of the sugar is consumed.

Naturally, the idea of consuming anything that's been involved with a "mat of mold" has people feeling some kind of way, especially since this particular type of mold under other circumstances is a major contributor to food spoilage and can even cause some types of pneumonia!

So far, popular medical opinion indicates that there's nothing too grave to be concerned about, however. "Medical experts have responded to these black mold concerns and have said that it is so refined that there isn't any reason to be concerned," Hickey says. "I still don't feel very comfortable about it though, especially for people that may have a mold allergy."

Indeed, some people might need to be a little more mindful than others. "Citric acid is 'generally recognized as safe' (GRAS) by the USDA, but there have been reports of citric acid causing canker sores, atopic dermatitis, inflammatory reactions, and stomach upset in some people," Julson says. "People who are extremely mold or yeast sensitive or allergic/sensitive to corn, beet, or cane sugar/starches may want to avoid citric acid since these items are used in the production of citric acid."

That said, citric acid has been credited with some pretty impressive feats, such as protecting the brain thanks to its antibiotic and anti-inflammatory properties. It's also linked to improved nutrient absorption, and has been tied to improved bone health, as well.

Some of the properties that make citric acid body-beneficial are also why they're used in other products. "Citric acid is used as an additive because of its antibiotic properties. In some canned foods, it is used to protect against botulism," says certified fitness instructor and Anabolic Bodies CEO Eddie Johnson via email.

Indeed, its preservative powers make it a natural for inclusion in everyday staples like ice cream, canned goods, wine, jams, applesauce, fish and shellfish because it keeps the product's pH balanced and prolongs its shelf life, according to Julson. Plus citric acid "adds a pleasant tart taste to fruit-flavored products, especially candy and beverages," she says.

Even if you're fastidious about non-naturally occurring citric acid consumption, there's still a pretty good chance that you'll come into contact with it, as it's a common component of makeup, chemical peels, bath bombs, detergents, cleaning supplies and even supplements. Citric acid stabilizes active ingredients in medications and improves their taste. Its antibacterial properties make it an effective disinfectant, which is why it's added to cleaning products.

"I swear by the amazing benefits of citric acid for the skin," says Alisha Lawson, a product development expert who specializes in beauty products for cosmetics company Shiny Leaf. "It treats several skin problems like mild acne, dark spots, clogged pores, and wrinkles," she says, adding that certain formulations are known to help brighten complexion and even out skin tone.

Fortunately, this doesn't seem like an ingredient we need to worry too much about. "Most studies have found citric acid to be safe, and some have even found it to be neuroprotective [protecting nerve cells against damage or degeneration], " says dietician Julson. "Consuming large quantities can certainly damage teeth or irritate the intestines, but for most healthy individuals in small doses, it is relatively benign."