Updated on April 13, 2023
Every time someone eats a hamburger, there’s a risk they’re exposing themselves to a substance that might cause or exacerbate autism—so major food companies, like McDonald’s, are scrambling to pull it from their products. The substance is calcium propionate, and a growing body of scientific literature suggests that limiting exposure to it is critical to protecting health.
Calcium propionate is widely used in the food industry as an edible preservative and antifungal agent; products such as fruit, packed meat, cheese, and bread are routinely sprayed with heavily diluted calcium propionate to prevent mold from taking root and causing spoilage. And while it is effective in its antifungal role, research suggests that calcium propionate might contribute to the development and exacerbation of autism spectrum disorder (ASD) due to its adverse impact on the gut microbiome.
Because of the suspected relationship between calcium propionate and autism, many consumers are now avoiding products that contain the preservative, and food producers are reformulating their offerings in response to this changing demand. However, simply limiting intake of calcium propionate might not be sufficient to restore gut health and prevent damage. Instead, individuals seeking to minimize or eliminate calcium propionate exposure should simultaneously support the body’s natural gastrointestinal defenses through butyric acid supplementation.*
Although many consumers are vigilant in avoiding artificial ingredients at odds with our natural physiological processes, calcium propionate might not initially elicit the same level of caution. This is because calcium propionate—while lab-created—is modeled after a chemical called propionic acid, which is naturally produced by the bacteria of the gut microbiome when the digestive system breaks down fiber. Calcium propionate, a solid form of propionic acid, was therefore long believed to be compatible with human physiology.
In the body, propionic acid is not used primarily for its antifungal properties. Instead, it is a precursor to other biological chemicals like succinyl-CoA, which cells use to break down stored energy and prepare it for immediate use. The rate of propionic acid metabolism is affected by a plethora of genetic, microbiotic, and environmental factors, and the majority of people have more than enough of it to support their bodily processes. However, having an overabundance of propionic acid might be a problem—especially for individuals with ASD.
In the laboratory, researchers have found that infusions of propionic acid into the brain tissue of mice cause the mice to develop behavioral symptoms that are consistent with autism spectrum disorder. These behavioral symptoms include reduced propensity to socialize, repetitive motions, abnormal interest in food objects, and perseveration of ineffective actions. Increasing the dose of propionic acid increases the intensity of these symptoms, meaning that additional consumption of propionic acid might do the same to individuals who have ASD.
Individuals with ASD are prone to having excess propionic acid due to ASD-related microbiome abnormalities and highly restricted diets, making them uniquely vulnerable to further damage. However, healthy people might also be affected; while they might not become debilitated by excess exposure to propionic acid, such exposure might cause mild ASD-like symptoms they would not experience otherwise.
These symptoms might not be easy to detect and they should dissipate quickly as propionic acid is cleared from the body. However, lasting damage might be occurring as a result of the substance’s impact on the microbiome and the brain.
The gut is the site of most propionic acid synthesis because it is where bacterial colonies of the microbiome consume dietary fiber and secrete propionic acid or other similar substances. Under ideal conditions, the many different species of bacteria that comprise the gut microbiome have population sizes within a narrow range of proportions; having a disproportionate amount of one species of bacteria might be harmful and lead to starvation of another species. Additionally, having too many of one species might lead to excessive production of the substance that the species contributes when digesting fiber.
Deviations in the proportion of species can occur for various different reasons, one of which is higher consumption of external nutrients that favor certain bacteria over others. When detrimental bacteria are favored, the immune system responds with an increased inflammatory response in an effort to remove them. However, an over-stimulated inflammatory response can contribute to the gastrointestinal problems associated with ASD, while also harming beneficial gut microbiota. Furthermore, an over-stimulated inflammatory response caused by the immune system can over-stimulate the gut-brain axis, which can in turn cause behavioral and psychological disturbances, such as the acute anxiousness observed in ASD.
Excess propionic acid can cause significant disruptions of the microbiome because propionic acid signals the gut’s immune system to activate an inflammatory response. This response can subsequently harm beneficial bacteria that secrete butyric acid—a highly versatile short-chain fatty acid with multiple critical functions—more than it harms the bacteria secreting propionic acid. Under normal conditions, the inflammatory response resolves itself.
However, in individuals with ASD, the conditions of the gut are more variable and require special control. As such, bacteria responsible for producing butyric acid are suppressed, while the bacteria that produce propionic acid become widespread. This can cause a further exacerbation of the individual’s gastrointestinal symptoms because butyric acid is responsible for signaling the immune system to down-regulate the inflammatory response in the gut.*
Furthermore, the non-immune systems of the gut can’t function effectively because they’re forced to use propionic acid, which is an inferior energy source that cells can’t process as efficiently as butyric acid. Propionic acid subsequently accumulates in the gut and elsewhere, inducing an ever greater inflammatory response and further aggravating ASD symptoms.
In addition to increasing the severity of ASD symptoms, propionic acid might also have a causative relationship with the development of the disorder due to its direct neurological impact. Both propionic acid and butyric acid readily cross the blood-brain barrier and are used by neurons as an energy source, with especially heavy usage occurring during early fetal development. Due to the acute sensitivity of the brain at this time, researchers believe that excess propionic acid exposure in early pregnancy might be one of the factors that contribute to the development of ASD.
This means that pregnant women should avoid consuming foods that are known to be treated with calcium propionate. If consuming them is necessary, then an acceptable alternative is to wash the foods to remove as much of the chemical as possible. And although there are no studies documenting newborns or infants acquiring ASD as a result of propionic acid exposure, excess exposure might cause invisible damage nonetheless.
In the brain, propionic acid is a second-class energy source, just as it is in the gastrointestinal tract. Concentrations of propionic acid can thus grow, eventually causing the cellular dysfunction associated with ASD symptoms.
Rising public awareness about the link between calcium propionate and autism is already causing consumers to change their habits and spurring the food industry to choose safer anti-fungal alternatives, reducing the aggregate level of exposure. Although removing dietary sources of propionic acid is essential to optimizing health and can help manage ASD symptoms, fortifying gut health and repairing the microbiomes of individuals who have experienced profound deviations in pH requires outside help.
One of the most promising ways to support gut health is via butyric acid supplementation.* Of particular note are advanced formulations, such as AuRx from Tesseract Medical Research, which is specifically designed to restore the microbiome of individuals with ASD and can possibly create a more beneficial level of symptom remission than removing dietary calcium propionate intake alone.*
Critically, supplemental butyric acid provides the cells of the gut and the brain with their preferred energy source, potentially down-regulating the inflammatory response, easing gastrointestinal distress, and supporting healthy neurological function.* As a result, the user’s microbiome can take time to recover without prolonged exacerbation of ASD symptoms.* And while extant propionic acid might remain in the user’s gastrointestinal tract, providing these cells with butyric acid via supplementation can give them sufficient additional energy to clear the excess propionic acid without leaving the individual to suffer in the meantime.*
Thanks to the innovative repurposing of butyric acid as a therapy, individuals with ASD now have an invaluable resource to help them recover from destabilizing factors like calcium propionate.* Additionally, by promoting the balanced growth of microbiota, the gut is better able to cope with future deviations of pH that might result from diet.* Strategically integrating a high-quality butyric acid supplement might thus be a critical component of ongoing ASD management.*
The power of Tesseract supplements lies in the proprietary science of proven nutrients and unrivaled smart delivery, making them the most effective for supporting gastrointestinal health and neurological health.*
Adams JB, Johansen LJ, Powell LD, et al. 2011. BMC Gastroenterology. 11:22.
Biggs AR, El-Kholi MM, El-Neshawy S, Nickerson R. 1997. Plant Disease. 81(4):399-403.
Den Besten G, van Eunen K, Groen AK, et al. 2013. Journal of Lipid Research. 54(9):2325-2340.
Frye RE, Nankova B, Bhattacharyya S, et al. 2017. Frontiers in Immunology.
MacFabe DF, Cain DP, Rodriguez-Capote K, et al. 2007. Behavioral Brain Research. 176(1):149-169.
Thomas RH, Foley KA, Mepham JR, et al. 2010. Journal of Neurochemistry. 113(2):515-529.
Valinksy, J. 2018. CNN Money.
Walker AW, Duncan SH, McWilliam LEC, et al. 2005. Applied Environmental Microbiology. 71(7):3692-3700.