Citric Acid From Mold: How Manufactured Citric Acid Is Made, the GMO Question, and What the Evidence Shows

Citric acid appears on ingredient lists for soft drinks, candy, canned vegetables, jams, frozen foods, supplements, and cleaning products. Because citric acid occurs naturally in lemons and limes, many people assume the additive comes from citrus fruit. In fact, nearly all citric acid used in food is manufactured by growing a black mold, Aspergillus niger, on sugar solutions, often derived from corn. Online articles have raised alarms that people are eating “GMO mold” and that manufactured citric acid causes inflammation and illness.

This article explains how citric acid is made, what regulators say about its safety, what a widely cited 2018 case series reported, whether genetically modified organisms are involved, and what people who suspect they react to citric acid can do.

How Citric Acid Is Made

Citric acid was first extracted commercially from lemons and limes in the 19th century, largely in Italy. In 1917, food chemist James Currie discovered that certain strains of Aspergillus niger produce large amounts of citric acid when grown on sugar solutions, and commercial fermentation began in 1919. The fungal process was far cheaper than extraction from fruit and quickly replaced it. A 2020 review in Critical Reviews in Microbiology by Bikash Behera describes Aspergillus niger as a workhorse of industrial biotechnology for citric acid production.

In modern production, Aspergillus niger is grown in large fermentation tanks on a medium containing sugars from sources such as corn starch hydrolysate, cane or beet molasses, or other carbohydrates. The mold converts sugar to citric acid, which is then separated from the fungal biomass, precipitated, purified, and crystallized. The FDA’s regulation for citric acid (21 CFR 184.1033) describes it as a naturally occurring constituent of plant and animal tissues that may be produced by recovery from sources such as lemon or pineapple juice, by fermentation with Candida yeasts, or by solvent extraction from Aspergillus niger fermentation liquor, and it lists citric acid among substances affirmed as generally recognized as safe.

Citric Acid in the Body

Citric acid is not foreign to the human body. Every cell uses citrate in the citric acid cycle, also called the Krebs cycle, the central metabolic pathway that generates energy from carbohydrates, fats, and proteins. The body produces and breaks down large amounts of citrate daily. Dietary citric acid from fruits, juices, and additives is absorbed and metabolized through the same pathways. Citrate in urine helps prevent kidney stones by binding calcium, which is why potassium citrate is prescribed for some people with recurrent stones and why lemon juice is sometimes recommended. A 2015 Cochrane review by R. Phillips and colleagues, including seven studies with 477 participants, concluded that citrate salts prevent new stone formation and reduce stone growth in people with calcium oxalate stones, though study quality was moderate to poor. Citric acid is also used in medicines, as an anticoagulant in stored blood products, and in many cosmetic and cleaning products.

Why Citric Acid Is Used in Food

Manufacturers add citric acid for several reasons: it provides a tart, sour flavor in drinks and candies; lowers pH to help preserve canned foods and prevent microbial growth; acts as an antioxidant synergist that slows browning and rancidity; and chelates metals that can affect color and flavor. Its versatility explains why it is one of the most widely used food additives in the world.

Product type	Why citric acid is added
Soft drinks and juices	Tart flavor, preservation
Candy and gummies	Sour taste
Canned vegetables and tomatoes	Acidification for safe canning
Jams and jellies	Helps pectin set; flavor
Frozen fruit and fresh-cut produce	Prevents browning
Supplements and medicines	Flavor, stability, effervescence

The 2018 Case Reports

A 2018 paper in Toxicology Reports by I. E. Sweis and B. C. Cressey of the Department of Surgery at the University of Illinois at Chicago drew attention to manufactured citric acid. The authors noted that about 99 percent of manufactured citric acid has been produced with Aspergillus niger since 1919, that 2.3 million tons were produced in 2016, mostly in China, with about 70 percent used in foods and beverages, and that Aspergillus niger is a known allergen. They described four patients who experienced repeated inflammatory symptoms, including respiratory symptoms, joint pain, irritable bowel symptoms, muscle pain, and fatigue, after consuming foods, beverages, or vitamins containing manufactured citric acid, with improvement when they avoided it. The authors hypothesized that residues from the fermentation process might trigger inflammatory reactions in susceptible people and called for further studies.

What the Case Reports Can and Cannot Show

Case reports are valuable for raising hypotheses, but they cannot establish that a substance causes illness. The four patients were not compared with a control group, symptoms were self-reported, and other dietary factors or conditions may have contributed. Avoiding processed foods containing citric acid also often means avoiding many other additives and changing diet overall, which could explain improvements. To test the hypothesis, researchers would need controlled studies, such as double-blind challenges in which patients receive manufactured citric acid or a placebo without knowing which. No such studies have been published. The paper raised the possibility that fragments of the mold or fermentation byproducts remain in purified citric acid, but it did not present laboratory evidence measuring such residues.

It is also worth noting that billions of people consume manufactured citric acid daily without apparent harm, which suggests that, if reactions occur, they affect a small subset of people. Mold allergies are common, and some individuals may react to trace contaminants in various foods. People with severe mold allergies or unexplained symptoms linked to processed foods may reasonably discuss citric acid with an allergist.

Is There GMO Mold in Citric Acid?

Claims that citric acid is made from “GMO mold” mix several issues. Industrial Aspergillus niger strains have been improved over decades, mostly through classical mutation and selection, and some modern strains may be genetically engineered. The sugar used for fermentation often comes from corn, much of which in the United States is genetically engineered. However, the purified citric acid that ends up in food is a simple organic molecule that contains no DNA or protein from the mold or the corn. Under U.S. bioengineered food disclosure rules, highly refined ingredients without detectable modified genetic material generally do not require disclosure. Organic standards permit citric acid produced by microbial fermentation of carbohydrate substances, though organic products cannot use ingredients from genetically engineered sources.

How Common Are Reactions to Food Additives?

Many people believe they react to food additives, but confirmed reactions are less common than self-reported ones. Allergy specialists note that true allergic reactions to most additives are rare, and that double-blind, placebo-controlled food challenges, in which neither the patient nor the clinician knows whether the additive or a placebo is given, are needed to confirm a reaction. Some additives, such as sulfites in asthma and certain colors in sensitive individuals, have documented reactions in subsets of people. For citric acid, published evidence consists mainly of the four case reports and anecdotal accounts. Because citric acid is chemically identical whether from fruit or fermentation, any reactions specific to manufactured citric acid would likely involve trace impurities, which would vary by manufacturer and purification quality.

For People Who Suspect Sensitivity

Track symptoms. Keep a food and symptom diary to look for patterns.

Work with a clinician. An allergist or gastroenterologist can evaluate symptoms, test for mold allergy, and supervise an elimination diet followed by rechallenge.

Read labels. Citric acid is listed by name on ingredient lists; it also appears in supplements and medications.

Use whole foods. Choosing fresh, minimally processed foods naturally reduces additive intake.

Consider other causes. Symptoms attributed to additives may have other explanations, such as food intolerances, reflux, or irritable bowel syndrome.

Citric Acid Versus Other Acidulants

Food manufacturers can choose among several acids for flavor and preservation. Malic acid, found naturally in apples, provides a lingering tartness and is common in sour candies. Tartaric acid, from grapes, is used in some baking powders and wines. Lactic acid, produced by bacterial fermentation, appears in fermented foods and some beverages. Phosphoric acid gives colas their sharp bite. Ascorbic acid (vitamin C) is used as an antioxidant. Many of these acids are also produced commercially by fermentation or chemical synthesis rather than extraction from their natural sources. Citric acid is popular because it is inexpensive, has a clean, fruity sourness, and performs multiple functions. People who avoid citric acid may find other acidulants in the same products.

Citric Acid and Dental Health

Acidic foods and drinks, including those containing citric acid, can contribute to dental erosion, the gradual loss of tooth enamel from acid exposure. Frequent sipping of sodas, sports drinks, citrus juices, and sour candies is a common cause. Dentists recommend limiting how often acidic drinks are consumed, using a straw, rinsing with water afterward, and waiting before brushing so that softened enamel can reharden. This concern applies to citric acid regardless of its source, since natural fruit acids have the same effect.

Citric Acid in Supplements and Medicines

Citric acid and citrate salts appear widely in supplements and medicines. Effervescent tablets combine citric acid with bicarbonate to fizz in water. Magnesium citrate and calcium citrate are common mineral supplement forms, with calcium citrate absorbed well even without food. Potassium citrate is prescribed for kidney stone prevention, and sodium citrate is used in some oral rehydration solutions and as an anticoagulant in blood collection. People who suspect sensitivity to manufactured citric acid should be aware of these sources but should not stop prescribed medications without consulting a clinician.

The Broader Question of Industrial Fermentation

Citric acid is one of many food ingredients produced by microbial fermentation. Others include vitamin B12, many vitamins and amino acids, enzymes used in cheese making and baking, xanthan gum, and some flavors and colors. Industrial fermentation has a long safety record, and regulators evaluate the identity and purity of fermentation-derived ingredients. Newer precision fermentation methods, which use engineered microbes to produce specific proteins such as dairy proteins, raise additional questions about allergens and labeling, as discussed in our article on precision fermentation dairy. Understanding fermentation helps put concerns about citric acid in context: the process itself is not unusual, but the purity of the final ingredient matters.

Key Facts at a Glance

About 99 percent of manufactured citric acid has been produced with Aspergillus niger since 1919, and 2.3 million tons were produced in 2016, about 70 percent for food and beverages. The FDA lists citric acid as generally recognized as safe. Citric acid is part of human metabolism, and citrate salts help prevent kidney stones. A 2018 report of four patients suggested manufactured citric acid might trigger inflammatory reactions in susceptible people, but no controlled studies have tested this. Purified citric acid contains no genetic material from mold or corn.

Common Myths

“Citric acid comes from lemons.” Nearly all citric acid in processed food is made by fungal fermentation, not extracted from citrus.

“Manufactured citric acid contains live mold.” The mold is removed and the acid purified; the final product does not contain living organisms.

“Citric acid is a GMO.” Citric acid is a simple molecule; purified citric acid contains no genetic material, though fermentation sugars may come from GM corn.

“Citric acid is toxic.” Citric acid is part of normal metabolism and is safe for most people; the open question concerns possible reactions to impurities in a small subset of people.

“Natural citric acid is healthier.” The molecule is identical; any difference would relate to impurities, not to citric acid itself.

Key Terms

Citric acid: A weak organic acid found naturally in citrus fruits and produced industrially by fermentation.

Aspergillus niger: A common black mold used industrially to produce citric acid and enzymes.

GRAS: Generally Recognized as Safe, an FDA designation for substances considered safe based on scientific evidence or long history of use.

Krebs cycle: The central metabolic pathway in cells that uses citrate to generate energy.

Elimination diet: A temporary removal of suspected foods or additives followed by reintroduction to identify triggers.

The Bottom Line

Manufactured citric acid is made by fermenting sugars with Aspergillus niger and purifying the result into a molecule identical to the citric acid in fruit. It is widely used, considered safe by regulators, and part of normal human metabolism. A 2018 case series raised the possibility that impurities from the fermentation process might trigger reactions in some people, but this hypothesis has not been tested in controlled studies. Claims that citric acid contains GMO mold misunderstand the purification process. People who suspect sensitivity can work with clinicians on structured elimination and rechallenge, and anyone wishing to reduce additive intake can focus on fresh, minimally processed foods.

Further Reading

The FDA’s regulation on citric acid (21 CFR 184.1033) describes approved production methods. Reviews of citric acid production describe the fermentation process in detail. The 2018 case series in Toxicology Reports presents the hypothesis of reactions to manufactured citric acid. Allergy organizations provide guidance on evaluating suspected food additive reactions.

Mold Allergy and Food

Mold allergies are common and usually involve inhaled spores causing respiratory symptoms such as sneezing, congestion, and asthma. Some people with mold allergies wonder whether foods made with molds or fermentation, such as aged cheeses, mushrooms, vinegar, soy sauce, or fermented beverages, could trigger symptoms. Reactions to such foods are generally uncommon, and allergists do not routinely advise mold-allergic patients to avoid all fermented foods. Purified ingredients like citric acid would be expected to contain far less mold-derived material than foods where molds remain present. Still, individuals differ, and anyone with a clear pattern of symptoms after specific foods should seek evaluation.

Labeling and Sources

U.S. food labels list citric acid by name but do not indicate how it was produced or where. Some manufacturers specify “citric acid from non-GMO sources” or carry non-GMO verification, which typically requires that fermentation feedstocks not be genetically engineered. Organic products may use citric acid made by microbial fermentation of carbohydrate substances under the USDA National List. People who want to avoid manufactured citric acid entirely must rely on whole foods or products that use lemon juice for acidity, since there is no labeling distinction between citric acid from fruit and from fermentation.

Questions to Ask Your Doctor

If you suspect reactions to food additives, consider asking: Could my symptoms be caused by an allergy, intolerance, or another condition? Would allergy testing, including for mold allergy, be useful? How should I conduct an elimination diet safely, and how long should it last? How should I reintroduce foods to identify triggers? Should I see a registered dietitian to ensure my diet remains nutritionally complete while avoiding certain additives? A structured approach helps avoid unnecessary dietary restriction while identifying real triggers.

Looking Ahead

As interest in food additives grows, researchers may conduct controlled studies to test whether manufactured citric acid causes reactions in people who report sensitivity, and to measure potential fermentation residues in commercial products. Regulators have also announced broader reviews of food chemicals and the GRAS process, which could include older ingredients. Until more evidence emerges, citric acid remains considered safe for the general population, with individual evaluation appropriate for people with unexplained symptoms.

A Balanced View

The story of citric acid shows how a common ingredient can become controversial when consumers learn how it is made. Fermentation with mold sounds unappetizing, but it is a long-established, well-controlled industrial process that yields a pure, familiar molecule. The 2018 case reports deserve attention as a hypothesis, and people with persistent symptoms should be evaluated individually. Yet case reports are not proof, and the vast majority of people consume citric acid without problems. Balancing openness to new evidence with an understanding of how ingredients are made and regulated helps consumers make informed choices without unnecessary fear.

Citric Acid in Home Use

Citric acid powder is sold for home canning, cheese making, cleaning, and descaling kettles and coffee makers. In home canning, adding citric acid or lemon juice to tomatoes ensures sufficient acidity to prevent the growth of Clostridium botulinum, following tested recipes from sources such as the USDA. As a cleaner, it dissolves mineral deposits. Concentrated citric acid powder can irritate eyes and skin, so it should be handled with care and stored away from children. These uses involve the same manufactured citric acid found in foods.

For people avoiding manufactured citric acid, bottled lemon juice is often used as an alternative acidifier in canning, since tested recipes specify bottled juice for its consistent acidity.

Comparing Natural and Manufactured Sources

A lemon contains roughly 5 to 6 percent citric acid by weight in its juice, and other fruits such as limes, oranges, grapefruit, and berries also contain substantial amounts. A glass of orange juice provides citric acid comparable to or exceeding the amount in many soft drinks. The body handles citric acid from these sources the same way it handles manufactured citric acid. This helps put intake from additives in perspective: people consuming fruits and juices already ingest considerable citric acid. Any concern specific to manufactured citric acid therefore relates to potential impurities rather than to the acid itself.

For most people, the choice between fruit-derived and manufactured citric acid is a matter of preference rather than health.

How Regulators Evaluate Fermentation Ingredients

Regulators assess fermentation-derived ingredients by examining the production organism, the manufacturing process, and the purity and composition of the final product. For citric acid, specifications in the Food Chemicals Codex set limits on impurities such as heavy metals and oxalate. Manufacturers are responsible for meeting these specifications, and the FDA can take action against products that do not. The GRAS framework has been criticized for allowing companies to self-determine safety for some ingredients, though citric acid’s affirmation in federal regulations predates these concerns. Recent federal initiatives to review chemicals in food may prompt reassessment of older ingredients.

Testing for fungal proteins or other fermentation residues in purified citric acid is not part of standard specifications, which is one gap the 2018 authors highlighted.

Practical Tips for Reducing Additive Intake

Cooking more meals from whole ingredients naturally reduces intake of citric acid and other additives. Choosing plain frozen fruits and vegetables without added ingredients, unflavored dairy, and fresh produce limits exposure. For canned goods, comparing labels can reveal brands without added acids, though acidification is required for some products for safety. Making beverages at home with fresh citrus or herbs replaces sodas and flavored drinks. These steps are useful for anyone wishing to reduce processed food intake, regardless of concerns about specific additives.

Practical Takeaways

Most people do not need to avoid citric acid. Those with persistent unexplained symptoms after eating processed foods can keep a symptom diary and work with a clinician on a structured elimination and rechallenge. People with mold allergies who notice reactions should mention them to an allergist. Anyone choosing to minimize processed foods will naturally reduce citric acid intake. For home canning, follow tested recipes and use citric acid or bottled lemon juice as directed to ensure safety, regardless of personal preferences about additives in processed foods.

Above all, base decisions on evidence and personal experience evaluated carefully, rather than on alarming headlines.

Key Takeaway for Shoppers

When you see citric acid on a label, it almost certainly means a purified, fermentation-derived ingredient used for tartness or preservation. For the vast majority of people, it poses no health concern. If you suspect it bothers you, a careful, clinician-guided approach is the best way to find out, since many factors can cause digestive or inflammatory symptoms, and unnecessary restriction can make eating harder without benefit.

Reading labels and choosing more whole foods remains a simple, effective strategy for anyone wishing to reduce additives overall.

Questions Readers Often Ask

Is citric acid the same as vitamin C? No; vitamin C is ascorbic acid, a different compound, although both occur in citrus fruit. Does citric acid damage the stomach? Stomach acid is far stronger than food levels of citric acid, so it does not harm a healthy stomach, though acidic foods can aggravate reflux in some people. Can citric acid help preserve homemade foods? Yes, when used according to tested canning recipes.

Is citric acid safe during pregnancy? Yes, in normal food amounts; it is a normal part of metabolism and found in many fruits. Can children have foods with citric acid? Yes, though limiting sour candies and acidic drinks helps protect children’s teeth from erosion. Does cooking destroy citric acid? It is stable under normal cooking conditions, which is why it works well as a preservative in canned and processed foods across many product categories.

As with any ingredient, moderation and a varied diet are sensible guides for most people.

People with specific medical conditions, such as kidney disease or severe reflux, can ask their clinicians whether acidic foods or citrate supplements need special attention in their individual dietary plans.

When in doubt, a registered dietitian can help.

Frequently Asked Questions

Is citric acid made from mold?

Most manufactured citric acid is produced by fermenting sugars with the mold Aspergillus niger, then purified. The final product is chemically identical to citric acid in fruit.

Is manufactured citric acid safe?

The FDA considers it generally recognized as safe, and it is widely consumed. A 2018 case series suggested some people may react, but controlled studies are lacking.

Does citric acid contain GMOs?

Fermentation sugars may come from GM corn, but purified citric acid contains no genetic material.

Can citric acid cause allergies?

True allergy to citric acid itself is unlikely since the body makes citrate; some people may react to trace contaminants, but evidence is limited.

How can I avoid manufactured citric acid?

Read ingredient labels and choose fresh, minimally processed foods.

References

1. Sweis IE, Cressey BC. Potential role of the common food additive manufactured citric acid in eliciting significant inflammatory reactions contributing to serious disease states: A series of four case reports. Toxicology Reports. 2018;5:808–812. PMID 30128297
2. Behera BC. Citric acid from Aspergillus niger: a comprehensive overview. Critical Reviews in Microbiology. 2020;46(6):727–749. PMID 33044884
3. U.S. Code of Federal Regulations. 21 CFR 184.1033 Citric acid. ecfr.gov
4. Phillips R, Hanchanale VS, Myatt A, et al. Citrate salts for preventing and treating calcium containing kidney stones in adults. Cochrane Database of Systematic Reviews. 2015;(10):CD010057. PMID 26439475

Last updated: October 6, 2026