Decoding My Autism

For a long time, I've tried to understand what goes on in my brain. Along the way, I've learned some things and made discoveries that have helped me live a better life.

  • Dan Bell

Dynamic Duo Series: Digestion

Part 5 and last in the series exploring the Dynamic Duo and related issues more in depth

As I conclude this series about the Dynamic Duo, I want to touch on one more challenging area in autism - digestion and gut troubles. This post was originally going to be a catch-all post to touch on a few other things that the fight-or-flight response impacts. However, I ended up covering most of them in other posts, and I've learned a few things recently about what can impact digestion and thought it warranted a post by itself.

Like many autistics, my gut gets upset a lot. When it gets upset, I spend quite a bit of time in the bathroom.

Why this happens can be difficult to identify or explain sometimes, and everyone's problems are going to be different. But there are some commonalities that I will discuss. Some make the gut more active, while others make the gut less active. The combination of them can make for a gut that can be quite temperamental.

One of them is the fight-or-flight response. As I discussed when I first introduced the Dynamic Duo, the fight-or-flight response is overactive. One of the things that response does is slow down digestion. Digesting food requires a lot of blood flow to the gut, and fight-or-flight directs blood in the extremities instead, taking that blood away from the gut. So digestion gets slowed down. Zinc can help calm down fight-or-flight by lowering dopamine, which the fight-or-flight chemicals are made from. I explain more about how this works in my post on Fixation.

On the other hand, there's serotonin, which makes things more active. Serotonin in the brain helps regulate mood, but in the gut it does something else. It helps keep things moving through the digestion tract.

Serotonin in the gut is in some ways opposite to the serotonin in the brain. If you've read my other posts, I talk about how there's too little serotonin in the brain. However, there's actually too much serotonin in the gut. Gut serotonin can't get into the brain, and the brain has to make its own supply.

Like in the brain, too little Vitamin D is the problem here as well. Vitamin D helps make the serotonin in the brain, but in the gut it actually reduces how much is made. Vitamin D is low in autism, so too much serotonin is being made in the gut.

What does the extra serotonin do? The body uses how much serotonin is in the gut as a cue for how fast to move things along. Normally, the body makes serotonin in response to food, and extra serotonin if there are toxins in our food. The body uses that the extra serotonin as a cue that something in the food is bad, and it needs to flush it out. The result is diarrhea, or if things are bad enough, vomiting.

So, extra serotonin in the gut, coming from low vitamin D, gives the body a false alarm, making the body think the food is toxic, and it tries to flush it out.

And as a third factor, emotions can have a number of impacts on digestion, as everyone has experienced. Emotional impact on digestion is a complex subject. But in general, stress and anxiety can slow down (or stop) digestion, while anger and aggression can speed things up.

So, as you can see, with so many things going on in autism that can affect digestion, there's no easy answer as to what digestive symptoms might appear, or what would be causing them. And I haven't even started on food sensitivities, which is another topic by itself.

But what I do know is that the Autism Dynamic Duo, vitamin D and zinc, can help. They affect the different things that are negatively impacting digestion, by regulating serotonin, helping with mood, and calming the fight-or-flight response.

This is the final post in a series of posts about the Autism Dynamic Duo. The other posts: An intro to the Duo and Sleep, Fixation, Anxiety, Aggression, and Social Learning.


Zeliadt, N. (2014, November 19). Diverse dopamine defects found in people with autism. Retrieved February 3, 2019, from

Patrick, R. P., & Ames, B. N. (2014, June). Vitamin D hormone regulates serotonin synthesis. Part 1: Relevance for autism. Retrieved February 3, 2019, from

Mayer, E. A. (2018). The mind-gut connection: How the hidden conversation within our bodies impacts our mood, our choices, and our overall health. New York: Harper Wave.

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