Autism is on the rise…big time. The medical community’s most common “answers” as to why this is happening range from “it’s unclear” to generalities including genetics, environmental toxins, and many others, leaving parents scratching their heads as potentially risky medications are prescribed for their children without solid answers to back them up.
The numbers from the Centers for Disease Control (CDC) illustrate this frightening increase: in the year 2000, 1 in 150 children were diagnosed with autism spectrum disorder; in 2012, that number rose to 1 in 68; finally, in 2018, diagnosed autism cases increased to 1 in 59. Where does it end? Will there ever be an answer?
New research may be zeroing in on a potential culprit that points to a problem created when pregnant women eat certain types of food. Scientific Reports has published the results of research done at the University of Central Florida (UCF) College of Medicine, which found that high levels of propionic acid (PPA) in the diets of pregnant women can “reduce the development of neurons in fetal brains.”
PPA extends the shelf life of various processed foods, and it’s a common preservative in packaged foods including commercially processed cheeses, breads, baked goods, etc. In recent years, the use of PPA has been expanded, and it’s now also used as a flavor enhancer in some packaged goods in addition to being used by the pharmaceutical and cosmetic industries.
So how is PPA associated with autism? UCF researchers identified molecular changes to neural stem cells when they’re exposed to high levels of PPA. Specifically, PPA causes inflammation and disrupts the balance between brain cells by reducing the amount of neurons while at the same time overproducing glial cells and damaging neural pathways.
The bottom line is that this combination of changes – and inflammation in particular – has been found in the brains of children diagnosed with autism spectrum disorder. Reduced neurons coupled with damaged neural pathways have been shown to interfere with communication abilities in the brain and to cause the behavioral issues associated with autism, including mobility problems, repetitive movements, and difficulty with social interactions.
The National Institutes of Health published a study that was undertaken to determine whether PPA has any effect on children’s behavior. Twenty-seven children participated in the double-blind study which included eating bread daily – a percentage of children were given placebos (bread without the PPA preservative) and the rest were given bread containing PPA. At the end of the study, there was no change in the placebo group, but the children who ate bread with PPA exhibited a “statistically significant difference” in behavior, including irritability, sleep problems, restlessness and attention problems. Conversely, children with behavioral problems who were taken off the preservative showed marked improvements in their behaviors.
Aside from the presence of high PPA levels in the body, scientists have found that the gut microbiome of autistic children is different from that of non-autistic children. When stool samples from autistic children were studied, the results showed that their stools contained not only higher levels of PPA, but also “significant differences” in gut microbiota and the diversity of that bacteria. Considering the importance of the gut-brain connection, it’s not surprising that a lack of bacterial diversity in the gut can cause inflammation in the brain.
According to Autism Speaks (the largest US autism advocacy group sponsoring research and promoting awareness), autistic children are also eight times more likely to have gastrointestinal problems such as GERD, chronic constipation, and abdominal pain.
Researchers at Texas Children’s Hospital in Houston noted that microbiome changes have been associated with GI issues in people who have neurodevelopmental disorders. In a separate study published in Scientific Reports, when autistic children received fecal transplants, which altered their gut microbiota, their GI issues improved – as did their behavior.
You may not see the actual term propionic acid or PPA on ingredient labels, but you may see one of its more common terms, including calcium propionate, propanoic acid, methyl acetate acid or ethylformic acid. Don’t be fooled if you see references to PPA as “naturally occurring” – propionic acid is a naturally occurring acid that results when bacteria ferments sugars in the intestines; it’s also found in sweat glands. However, industrial-made non-biological PPA is not the same chemical and is based on petrochemical reactions. In any case, an overabundance of PPA in the body occurs when too much of this industrial PPA preservative is consumed.
As functional medicine doctors have long known, a healthy gut microbiome is key to a healthy brain and body. Replacing processed foods with whole foods and making sure your diet includes a wide range of diverse vegetables and fruits – preferably organic – helps to create and maintain a healthy microbiome.