Posted on January 02 2015
A page written by Dr. Rupa Mukherjee, gastroenterologist at Beth Israel Deaconess Medical Center in Boston, on the link between nausea and the gastrointestinal system.
Nausea is not fun!
I’m sure many of you would agree. I’m a gastroenterologist, and I see many patients who complain about nausea. My patients describe this feeling in various terms - feeling queasy, needing to vomit, a raw tummy, stomach discomfort accompanied by an acid taste in the mouth. How would you describe it?
The American Gastroenterological Association defines nausea as an unpleasant, subjective feeling that one will vomit imminently (although as you know, nausea can occur with or without vomiting). While at times, acute nausea may serve a physiologic purpose – to rid the body of any harmful ingested substances – there are many other times when it may not serve any purpose at all. After all, think of motion sickness.
Nausea can affect our lives, our jobs, and our families
I think my patients would all agree that the sensation of nausea is distressing and can significantly affect their quality of life. Most patients with nausea due to an acute illness or “stomach bug” restrict their activities. Women who experience nausea and vomiting during pregnancy commonly describe fatigue, poor sleep, and irritability, all of which can affect family and social interactions. Patients who experience nausea as a byproduct of other treatments have similar experiences, causing them to restrict activities and social interaction. Nausea can also lead to many missed days at work. In one British study, pregnancy-related nausea led to the loss of 8.5 million working days per year and women with severe symptoms missed a mean of 62 hours of work during their pregnancy. Clearly, nausea is a big deal, not just for individuals but also for society as a whole.
What causes nausea?
There are many causes for acute and chronic nausea including gastrointestinal (GI) and non-GI conditions. These include the common morning sickness and motion sickness, and others such as infections, intestinal disorders such as stomach ulcers and acid reflux, irritable bowel syndrome, gallstone disease, headaches, medication side effects, and others. Celiac disease and gluten sensitivity are also common causes for nausea – a particular area of interest of mine.
So what is actually happening in our bodies during nausea?
Independent of the cause, nausea involves interactions between the stomach, the gut and its nervous system, and the central nervous system or brain. Let me try to simplify. The stomach has two major functions: secretion and motor function. When you eat food, a signal is sent to the brain that causes the stomach to secrete acid and various enzymes to break down the food. The stomach also acts as a reservoir in which food is stored, mixed and pushed into the small intestine through periodic contractions. Both of these functions – secretion and motor function – are controlled by the central nervous system through the vagus nerve, a nerve that extends from the brainstem into the abdomen.
In addition to periodic contractions, the stomach also produces electrical signals (or waves), similar to a circuit such as the heart, that control stomach motor function. These waves are primarily slow and produce rhythmic movement or oscillations throughout the stomach at three defined rhythms per minute.
Nausea is associated with disturbances in the rhythm of the slow waves – either cycling too fast (tachygastria), too slow (bradygastria) or mixed (bradytachygastria). Nausea appears to be proportional to the degree of gastric dysrhythmia – the more out of sync, the worse the nausea. Moreover, the nature of the food you eat - protein vs. fat. vs carbohydrates - affects this entire process.
The silver lining
Despite the complexity of the stomach, the good news is that there are effective and even simple treatments to manage nausea based on its underlying cause. In future posts, I will discuss in detail some of the major causes of nausea and explain what I’ve seen work and not work as a GI doctor.
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