Dietary Aversions and Preferences in Children with Autism
“They are a super picky eater. They won’t eat vegetables.”
These are some of the most common words I hear from the parents of my autistic patients. Of course, we all know that eating our veggies is healthy, but for a child on the spectrum what the bacteria would do with the vegetable fiber can have a massive impact on how their immune system and brain work. There are a few reasons they might dislike certain types of foods.
- Altered gut bacteria. They may have too many bacteria in the small intestine due to poor bowel motility which then could cause pain and bloating.
- Parietal lobe issues. It is also possible that a child on the spectrum could have their parietal lobes affected. This could lead to an aversion to the texture as well as the taste of certain foods. Since there is typically altered sensory perception with a child on the spectrum, including on the lips and tongue, this will impact how they perceive food textures and the taste of food itself.
- The foods they like may be exorphins. Certain foods like breads with gluten, for example, can activate opioid receptor sites. That is, when the child, eats these foods, he or she gets a boost of nature’s endogenous painkillers. This makes the child addicted to the very foods that have the potential to be the most problematic. When a parent asks me what foods their child should avoid, I typically ask them what foods they seem addicted to and we have some of the answers.
Pieces to the Puzzle: Immune System and Microbiome Crosstalk
Although the research is ongoing, it is becoming more apparent that either the child with autism or his/her mother suffer from a pattern of immune activation that can lead to disrupted gut barrier. This, in turn, contributes to an alteration not only in the gut bacteria, but also, in how the immune system in the brain respond to immune insults. Since these bacteria are responsible for metabolizing the food we eat and extracting from those foods essential nutrients, that then are used for building neurotransmitters, and modulating immune function, the alteration in gut bacteria can lead to an inflammatory cascade and cycle, which then affects the proper development of the nervous system. As the diet becomes narrower, it brings further nutrient depletion, causes more of a microbial imbalance, and leads to a pro-inflammatory environment. Although most people with chronic disease have some form of inflammatory response, researchers have found that when a subset of immune cells called TH17 are hyperactive, either in the mom during pregnancy, or the child themselves, we see an inflammatory response so imbalanced that a neurodevelopmental disease is more likely to develop.
A Few More Pieces: Bacteria, Fiber, and Immune Modulation
When bacteria eat different types of fiber from dark leafy green vegetables or grains, they make compounds called short-chain fatty acids (SCFA). These SCFAs activate several parts of the enteric nervous system, which then communicate with the central nervous system. Specifically, one SCFA called butyrate seems to particularly important. Butyrate is a primary energy source for cells in the large intestine used to ‘fix the gut’, but it also has a great impact on the immune system and healing the gut lining. It does this by multiple mechanism, but mainly by reducing bad bacteria that can be driving the immune issues in the first place. Butyrate helps turn off pro-inflammatory signals as well as turn on anti-inflammatory signals and bring balance back to the immune system by helping with something called T-regulatory cells. T regulatory cells do exactly what the name suggests, they regulate the immune response. This is especially important given that the brain and GI tract are in constant communication, not only via the vagal nerve, but the sympathetic nerve fibers send signals directly to the brain. Given that the microbiome and inflammatory cytokines are an important part of this relay system, their involvement with something like Autism should not be ignored.
For those of us that have been doing this enough, it is blatantly apparent that there is immune system involvement, with some articles showing upwards of 70% of children on the spectrum have an autoimmune disease process going on in their brain. Hence, to help modulate the altered immune response, the bacterial by-products of fermenting fibers can go a long way in helping bring balance to the immune response, gut lining, and nervous system.
Returning to the picky eater problem in children with autism, it appears that because of altered bacterial balance and possibly also sensory issues, they may be drawn to the very foods that sustain an inflammatory response, and conversely, naturally avoid those foods that might dampen that response and rebalance the gut microbiome. The concept of oral tolerance is where the immune system is told to ignore foods that are being consumed so they don’t contribute to an inflammatory response. This can be a large catch-22 in the sense that the less diverse a child’s diet, typically the lower their oral tolerance of foods, so unfortunately, the immune system and microbiome get painted into a corner that can be difficult to get out of.
A Picture Emerges
Although these are only a few pieces of the puzzle, giving the gut and immune cells of a child with autism what they need can really help. Eventually, the goal is to have these kids lose their taste aversion and start eating veggies and other healthier foods. To accomplish this, we have to address the root causes of their food aversions. This means addressing proper magnesium levels of the brain and re-balancing gut microbiota. Once we see how all the pieces are connecting, we can paint the clearest picture possible. Since each child is unique, each picture is unique as well. The good news is, once a path to healing is identified in a child, the effect can snowball in the sense that the fewer food aversions a child has, the better the gut and immune system work and so the better the brain works, which means the more foods they will eat and enjoy. That is, the food/health/immunity cycle becomes more favorable.
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This article was published originally on April 8, 2019.