Citric acid used as a preservative is safe for the vast majority of people. It holds FDA “Generally Recognized as Safe” (GRAS) status and appears in thousands of packaged foods, beverages, and canned goods. That said, the citric acid in your food almost certainly isn’t squeezed from lemons. It’s produced industrially using a mold called Aspergillus niger, and a small number of people appear to react to this manufactured form with digestive or inflammatory symptoms.
Understanding the difference between natural and manufactured citric acid, and knowing where the actual risks lie, can help you decide whether it deserves a spot on your personal watch list.
How Citric Acid Ends Up in Your Food
Citric acid occurs naturally in citrus fruits. Lemon juice contains about 5% to 6% citric acid (roughly 1.44 grams per ounce), and lime juice runs close behind at 4% to 5%. But the global demand for citric acid far exceeds what citrus farming could supply, so virtually all of the citric acid added to processed food is manufactured through fermentation. The process involves feeding sugarcane molasses to the mold Aspergillus niger in large tanks, where the organism converts the sugar into citric acid over several days.
The end product is chemically identical to the citric acid in a lemon. The concern some people raise is whether trace residues from the mold or the fermentation process carry over into the final ingredient. Regulatory agencies treat manufactured citric acid the same as the natural form, and it was granted GRAS status without a dedicated safety study of the manufactured version specifically.
What Regulators Say About Safety
The FDA lists citric acid under multiple food additive and GRAS regulations (21 CFR Parts 170 through 186), and it was reviewed by the Select Committee on GRAS Substances. No upper daily intake limit has been set for the general population, largely because citric acid is metabolized quickly and doesn’t accumulate in the body. The European Food Safety Authority takes a similar position. For most people, consuming citric acid in typical dietary amounts poses no measurable health risk.
The Inflammation Question
A 2018 case report series published in Toxicology Reports raised the possibility that manufactured citric acid could trigger inflammatory reactions in certain sensitive individuals. The paper documented four cases in which people with conditions like asthma, juvenile idiopathic arthritis, fibromyalgia, and autistic spectrum disorder appeared to improve when they eliminated manufactured citric acid from their diets. The authors noted that Aspergillus niger is a known potent allergen and hypothesized that residual proteins or compounds from the mold could set off allergic inflammatory cascades in genetically predisposed people.
This is a small case series, not a controlled trial, so it doesn’t prove that manufactured citric acid causes these conditions. What it does suggest is that a subset of people, particularly those with a genetic predisposition to mold allergies, may experience joint pain, muscle pain, or worsened inflammatory symptoms from regular exposure. If you have an existing inflammatory condition and suspect a food sensitivity, eliminating packaged foods with added citric acid for a few weeks and tracking your symptoms is a reasonable way to test it.
Digestive Sensitivity
The most commonly reported side effects of citric acid are digestive: stomach discomfort, nausea, or cramping, especially when consumed in large amounts or on an empty stomach. This is partly a simple pH issue. Citric acid is, after all, an acid, and concentrated doses can irritate the lining of the stomach and esophagus. People with acid reflux or gastritis tend to notice this more.
Some individuals also report digestive issues specifically with manufactured citric acid rather than the citric acid they get from eating actual fruit. Whether this is due to the mold-derived production process or to the higher concentrations found in processed foods isn’t fully settled. Either way, if citric acid in beverages or supplements consistently bothers your stomach, the pattern is worth paying attention to.
Effects on Your Teeth
Tooth enamel begins to dissolve when the pH at its surface drops below about 5.5. Many citric acid-containing drinks, especially sodas, energy drinks, and sour candies, sit well below that threshold. Even beverages buffered to a commercially common pH of 3.8 still cause measurable enamel erosion. Dentine, the layer beneath enamel, is even more vulnerable, beginning to break down at a pH of 6.3.
This doesn’t mean a squeeze of lemon in your water is destroying your teeth. The risk scales with frequency and duration of exposure. Sipping on an acidic drink throughout the day bathes your teeth in acid repeatedly, giving saliva no chance to remineralize the enamel between exposures. Drinking acidic beverages with meals, using a straw, and rinsing with plain water afterward all reduce contact time significantly.
Potential Benefits of Citric Acid
Citric acid isn’t purely a concern. It plays a useful role in mineral absorption. Research published in the journal Food & Function found that citric acid enhances iron uptake by weakening hydrogen bonds within food proteins, which improves their digestibility and releases more soluble iron for your body to absorb. This is one reason vitamin C-rich (and citric acid-rich) foods are recommended alongside iron-rich meals.
Citric acid also helps prevent kidney stones. It works by making urine less acidic, which reduces the formation of both calcium oxalate and uric acid stones. Doctors sometimes prescribe citric acid and sodium citrate combinations specifically for this purpose. Even outside of a prescription, regularly consuming citrate from dietary sources like lemon juice is a well-established strategy for people prone to kidney stones.
Who Should Pay Attention
For most people, citric acid as a food preservative is harmless in normal dietary quantities. The groups most likely to notice problems are people with mold allergies or sensitivities (who may react to residues from the Aspergillus niger fermentation process), people with acid reflux or sensitive stomachs (who may find concentrated citric acid irritating), and people who frequently consume highly acidic foods and drinks (who face a higher risk of dental erosion over time).
If none of those categories apply to you, citric acid on an ingredient label is not something to worry about. If one of them does, the practical step is straightforward: reduce your exposure for a few weeks and see whether your symptoms change. Citric acid is easy to spot on labels, and fresh, minimally processed foods naturally contain far less of it than packaged products do.