Autistic children often experience gastrointestinal discomfort, ranging from constipation to diarrhea. Indeed, it is challenging to study these symptoms using measurements like averages because digestive symptoms can be very individual. For instance, one review of 144 research studies of autistic people found that 4-46% experienced constipation, 2-76% experienced diarrhea, and 4-97% experienced ≥ 1 gastrointestinal symptom (1). Wow, what a range!
A big reason for the individual experience of digestion is our gut microbiota. These are all the bacteria that live inside our intestines, mainly in the large intestine. In fact, you have about as many bacterial cells on and inside your body as you do human cells. Trillions! Even more surprising, you have about 100 times more genes from these bacteria than your own human genes! Because your genes are so important in making you who you are, think what a huge role these bacteria can play in your health and life. Just like you have your own unique fingerprint, you also have your own unique assortment of bacteria that live inside your gut.
After learning a bit about your microbiota, you’re probably beginning to see why each person can have such different gastrointestinal symptoms, even after eating the same foods. Interestingly, autistic people seem to have a different milieu of microbiota in their intestines than those who are not autistic. In a study of many studies and a summary of all their data (called a systematic review and meta-analysis), researchers found that autistic children had higher amounts of some types of bacteria and lower amounts of other bacteria than non-autistic children (2). Notably, one of the reduced bacteria found across these studies was Bifidobacterium. This is one of the most common bacteria found in probiotic supplements at grocery stores or purchased online. It’s easy to understand why there is so much hype around probiotics (bacteria that have health benefits for humans) and prebiotics (fibers that probiotic bacteria eat) to support autistic people, especially their gut health.
While I think there is a lot of potential moving in this direction, we also need to be cautious. There are so many probiotic supplements out there, and because we all have such a unique set of microbial companions, we need to treat them as the truly unique friends that they are. Just because I love to eat garbanzo beans, this doesn’t mean that you love to eat them. And just because my microbiota thrive on certain types of fiber, this does not mean that yours thrive on the same type. There is no one-size-fits-all probiotic that’s going to fix everything. Ultimately, we need to move toward personalized nutrition and care to support autistic individuals and their families.
References:
1. Holingue C, et al. Gastrointestinal symptoms in autism spectrum disorder: A review of the literature on ascertainment and prevalence. Autism Res. 2018;11(1):24-36.
2. Iglesias-Vázquez L, et al. Composition of gut microbiota in children with autism spectrum disorder: A systematic review and meta-analysis. Nutrients. 2020;12(3):792.
