Throughout my years as an autism nutritionist, many parents have shared with me that their child with autism/ASD has been suffering from chronic gastrointestinal issues that in some cases, has been present for many years. In numerous instances, when families of children with autism/ASD have turned to their doctor for support, they have been turned away, given the disappointing conclusion that the chronic GI problem will “resolve itself” with time.
The fact is that up to 90% of children with autism/ASD suffer from some sort of chronic gastrointestinal condition (Buie et al., 2010b) and children with autism/ASD have higher rates of GID than typically developing children (McElhanon, McCracken, Karpen, & Sharp, 2014). A key meta-analysis on the subject found that children with autism/ASD have higher rates of diarrhea, constipation and abdominal pain than comparison groups; greater incidence of mega-rectum, resulting from muscle dysfunction or fecal impaction, has also been found to be elevated among children with autism/ASD and constipation (Afzal et al., 2003). Abnormalities of the GI tissue of children with autism/ASD and increased intestinal permeability have also been noted, as has damage to the tight intercellular junctions of gut mucosa, more commonly known as leaky gut (Horvath, Papadimitriou, Rabsztyn, Drachenberg, & Tildon, 1999; de Magistris et al., 2010, Horvath & Perman, 2002).
This chronic GI dysfunction is a particular concern, as they can affect digestion of food, absorption of nutrients and in some cases, affect a child’s sleep, growth and vitality. In addition, they are often a trigger for unwanted behaviors; autism/ASD severity, oppositional behavior and aggression, and rigid-compulsive behaviors have all been found to be significantly associated with GI problems among children with autism/ASD (Heberling, Dhurjati, & Sasser, 2013; Maenner et al., 2012; Peters et al., 2014).
So why does this happen to many children on the ASD spectrum and what might be the root cause? According to ASD and autism researchers, the two main reasons are: (1) inappropriate activation of the immune system, causing inflammation of the GI tract; and (2) differences in the types of bacteria present in the gastrointestinal tract of children with autism/ASD, that lead to GI symptoms.
The role of inflammation in autism/ASD
Inflammation is the body’s natural way of fighting off a harmful substance or injury in attempt to induce healing. However, when acute or short term inflammation turns into uncontrolled chronic inflammation, damage to the body’s organs and systems can occur over time. Children with ASD/autism, have repeatedly been shown to have increased levels of inflammatory cytokines or signaling molecules that promote inflammation, such as interleukin 5 (IL-5), IL-15, and IL-17 and lower levels of TGF beta 1, a protein that helps regulate the immune system. In a recent study, children with both ASD/autism + GI dysfunction had lower levels of the protein zonulin, which helps to regulate how permeable the intestinal wall is (and when elevated, is often an indicator of leaky gut). Both a proper personalized diet and nutritional supplements can help support the reduction of excessive inflammation in the body.
How to measure inflammation: Many practitioners use CRP to assess whether there is an inflammatory process occurring in the body; in addition, many different immune markers can also be assessed in blood work, as needed. Some functional medicine practitioners have begun to measure phospholipase A2 or PLA-2 in the urine, as this enzyme is elevated in a wide range of inflammation-related disorders and is a marker for increased risk of developing or worsening of inflammatory conditions.
Foods that lower inflammation: Consider adding garlic, grapes, nuts, olive oil, black and green teas, curcumin, ginger, resveratrol and mushrooms to your family’s diet to help reduce inflammation. Brightly colored fruits and vegetables should have a strong presence in your diet as well. Avoiding inflammatory foods such as processed foods, white flour and sugar is just as important. I highly recommend adding anti-inflammatory foods to any special diet being implemented by a children with autism/ASD.
The role of the microbiome: You are your bacteria!
Did you know our bodies are home to an estimated 40 trillion bacteria, that most of our gut bacteria belong to 30 or 40 species, and that there can be up to 1000 different species in all? Collectively, these gut bugs are called the microbiome, and they can do some amazing things for our health. Some species break down dietary fiber down into short-chain fatty acids so we can absorb and use them; and others metabolize compounds on our behalf and play a role in the synthesis of vitamins such as B’s and K. However, when pathogenic bacteria start to overpopulate the gut, this dysbiosis can contribute to inflammation seen in various conditions and disorders including autism/ASD.
In autism/ASD, pathogenic bacterial strains such as clostridia can cause illness and produce neurotoxins that can be absorbed from the GI tract. In addition, low levels of beneficial bacterial strains such as bifidobacterium have also been reported in children with ASD (Adams et al., 2011). This combined with yeast and pathogenic bacterial overgrowth that often occurs after the use of oral antibiotics (Santelmann & Howard, 2005; Shaw, Kassen, & Chaves, 2000) can contribute to a variety of both GI and behavioral problems.
The gut-brain connection
So how exactly are the gut and brain connected to one another? Research shows that the link between our gut and brain are mediated by hormones, the immune and nervous systems, specifically the central nervous and enteric nervous systems, which govern the function of the gut. Collectively, they are termed the gut-brain axis. A recent meta-analysis, published in the Journal of Neurogastroenterology and Motility and based upon the results of 15 human studies, found that Bifidobacterium and Lactobacillus probiotics were effective in improving psychiatric disorder-related behaviors including anxiety, depression, autism/ASD, obsessive-compulsive disorder, and memory abilities, including spatial and non-spatial memory.
In one recent study which compared children with autism/ASD, with and without GI symptoms, both groups with ASD had different gut flora populations than the typically developing groups. Interestingly, the group with GI issues + autism/ASD also differed from the autism/ASD group without GI problems. The researchers noted that the children with autism/ASD and GI issues tended to display worse behavior than children with autism/ASD that did not have GI problems.
How to assess gut bacterial health: Functional medicine practitioners often use comprehensive stool testing to assess bacteria cultured from the stool which can reflect one’s microbiome. Other tests can map out bacteria by DNA PCR method.
How to replenish healthy gut bacteria: Special diets such as SCD and GAPs diets can be very helpful in children with GI dysfunction. I also recommend fermented foods and diets rich in pre and probiotics for most children with autism/ASD and the whole family.
Buie T, Campbell DB, Fuchs III GJ, et al. Evaluation, diagnosis, and treatment of gastrointestinal disorders in individuals with ASDs: A consensus report. Pediatrics. 2010;125:s1-s18.
McElhanon BO, McCracken C, Karpen S, Sharp WG. Gastrointestinal symptoms in autism spectrum disorder: A meta-analysis. Pediatrics. 2014. http://eutils.ncbi.nlm.nih.gov. doi: peds.2013-3995 [pii].
Afzal N, Murch S, Thirrupathy K, Berger L, Fagbemi A, Heuschkel R. Constipation with acquired megarectum in children with autism. Pediatrics. 2003;112(4):939-942. http://eutils.ncbi.nlm.nih.gov.
Horvath K, Papadimitriou JC, Rabsztyn A, Drachenberg C, Tildon JT. Gastrointestinal abnormalities in children with autistic disorder. J Pediatr. 1999;35(5):559.
de Magistris L, Familiari V, Pascotto A, et al. Alterations of the intestinal barrier in patients with autism spectrum disorders and in their first-degree relatives J Pediatr Gastr Nutr. 2010;51(4):418.
Heberling CA, Dhurjati PS, Sasser M. Hypothesis for systems connectivity model of autism spectrum disorder pathogenesis: links to gut bacteria, oxidative stress, and intestinal permeability. Med Hypotheses. 2013;80(3):264.
Maenner MJ, Arneson CL, Levy SE, Kirby RS, Nicholas JS, Durkin MS. Brief report: Association between behavioral features and gastrointestinal problems among children with autism spectrum disorder. J Autism Dev Disord. 2012;42(7):1520-1525.
Peters B, Williams KC, Gorrindo P, et al. Rigid–compulsive behaviors are associated with mixed bowel symptoms in autism spectrum disorder. J Autism Dev Disord. 2014;44(6):1425-1432.
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