There are many reasons why the body might vomit. There are different pathways to the same result. Let me talk about two of those pathways.
One pathway is that of the body noticing a "toxin" such as a food allergen. In response to this "toxin", the body makes chemicals such as serotonin, and these chemicals eventually arrive at a trigger zone in the brain. At this trigger zone, the brain recognizes that it needs to get the person to vomit. These chemical messengers elicit the vomiting response.
Now let's talk about the second pathway to the same result of vomiting. The second pathway has to do with a direct nerve connection between an irritated digestive tract and the vomiting centers of the brain. We just talked about it a few moments ago.
In other words, there are multiple pathways to the same result - vomit. In fact, in many conditions, both pathways are present. If you have a child who has repeated episodes of FPIES and often vomits, their esophagus might eventually get irritated. If you have a child whose esophagus becomes too acidic because of gastroesophageal reflux disease, then the esophagus might also get irritated. If you have a child who has an allergic condition like eosinophilic esophagitis, then the esophagus might also get irritated. Irritate the esophagus enough, and a person might vomit.
Does this give you a better explanation of why I believe that reflux and food allergies including FPIES are not related in some ways. In other ways, they are related. When you look at a child who is vomiting, you might think that all vomiting comes from the same place. It doesn't. There are multiple pathways to the same result of vomiting. Each disease might follow only one of the pathways or more than one of the pathways. It really depends. If you want to improve the frequency of vomiting, you need to both figure out the disease and also figure out which vomiting pathways are being activated.
Back to my story of little Peter. He just kept on vomiting. The mother took him to see his doctor, and the doctor prescribed some histamine 1 blocker to Peter. Despite the medication, Peter continued to have multiple episodes of vomit. Why?
I'll give you two potential explanations. First, Peter could be vomiting because of something that has nothing to do with how much acid is in his stomach or esophagus. His vomiting might have nothing to do with irritation in his esophagus. It could be due to his age and the sphincter between the stomach and the esophagus being loose. It could be due to food allergies or some other medical condition. Second, histamine 1 blockers do not treat vomiting in the short term. They might decrease the amount of acid in the esophagus or in the stomach, but it can take a while for irritated esophaguses to heal. It might not happen overnight. Histamine 1 blockers work more under the principal that if stomach acid is causing pain in the esophagus, perhaps by decrease the amount of acid in the stomach, there will be less pain.
Eventually, Peter's mother took him back to the doctor and discussed how the histamine 1 blocker medication was not helping with the stomach pain. They had another discussion, and eventually over time with other changes, Peter did start to have less vomiting episodes. That's such a complicated topic that there's no time to discuss it during today's episode.
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