Why Does Anxiety Cause Nausea
Why Does Anxiety Cause Nausea? You’re waiting in line at the grocery store with your cart full of food. You just got back from seeing a movie and you have no idea what to do with yourself. A friend calls out to you from across the room because she just saw an advertisement on Facebook about a free ticket giveaway. All day long people keep asking you questions like “What are you doing tonight?” At work, someone tells you that the company is having a big event next week. And then there’s always that one person who asks exactly where you’re going tonight.
The more anxious you become, the more often you feel compelled to answer those questions because it gives you something concrete to focus on other than all the things stressing you out. This makes anxiety worse.
When we experience something new, such as meeting somebody new or traveling somewhere, our bodies respond by releasing chemicals called hormones that tell certain parts of the body to speed up their activities. These chemicals travel through the bloodstream to reach different areas of the body. One area affected by these hormones is the hypothalamus which controls many basic functions, including breathing, heart rate, temperature regulation and sleep cycles.
Another hormone released from the pituitary gland also affects the hypothalamus. If this hormone gets too high (called ACTH), it will stimulate the release of another important hormone called cortisol. Cortisol stimulates the liver to produce glucose so that the body can use it as energy. In addition, it helps the muscles and immune system function properly.
Our brains naturally want us to be safe and avoid threats. But sometimes these signals go awry. When the brain needs to alert the body to danger, it usually sends messages using two types of chemical transmitters called neurotransmitters. One type causes the smooth muscles of various organs to contract; the other type relaxes them. For example, serotonin is a neurotransmitter associated with relaxation and mood.
However, if excessive amounts of serotonin get into the bloodstream, it may lead to increased irritability and depression. Serotonin is produced by the pineal gland, located above the cerebellum. So if the cerebellum becomes overactive, it could trigger excess production of serotonin. This would make you feel restless and unable to sit still. Similarly, dopamine has calming effects and helps control movement and emotions. The excess dopamine creates feelings of restlessness and agitation.
One way to relieve stress is by getting enough sleep each night. Sleep deprivation disrupts normal hormonal functioning, resulting in elevated levels of the stress-related hormones adrenaline and cortisol. Both of these hormones play key roles in producing hunger pangs and causing cravings. Stress can also affect appetite by increasing ghrelin, a hormone that regulates how much food we eat. Ghrelin increases its effect after eating, making you less likely to stop eating once you start.
Stress can also contribute to gastrointestinal problems. Our guts contain trillions of bacteria known as the gut microbiome. Gut microbes help digest carbohydrates, proteins and fats. They also synthesize vitamin K, folate, iron, zinc and bile acids. Bacteria living in the colon convert fiber found in foods into short-chain fatty acids. Short-chain fatty acids have been shown to improve intestinal health and reduce inflammation. Some studies suggest that probiotics in yogurt can also provide relief from IBS symptoms. When the gut microbiome is disturbed, it can cause bloating and gas, diarrhea and constipation. In turn, these issues can increase stress.
The link between anxiety and GI disorders was first recognized in 1937 when researchers noted that patients suffering from severe cases of ulcerative colitis were also prone to mental illnesses. Since then, several theories have emerged linking GI conditions to psychiatric disorders. There are even reports that GI infections can cause schizophrenia and bipolar disorder.
In order to understand why anxiety might cause nausea, we need to look at how anxiety works in the human body. We know that anxiety attacks occur when the amygdala activates the sympathetic branch of the autonomic nervous system.
During an attack, neurons fire rapidly in the parasympathetic nerves that connect the spinal cord to the pelvic region. As a result, the smooth muscle tissues in the gut, especially the lower part, begin to spasm involuntarily. The smooth muscles in the upper part of the bowel, however, do not change. This leads to abnormally slow peristalsis, meaning that the intestines move only very slowly. Because slow transit time allows large particles of undigested food to accumulate, abdominal discomfort occurs. Severe episodes of anxiety can last for hours and even days. Afterward, people often report feeling nauseated.
So far, we’ve looked at the role that anxiety plays in triggering GI distress. Next let’s see how it can cause nausea.
Causes of Gastrointestinal Disorders Associated With Anxiety
Gastrointestinal conditions are common among individuals with anxiety disorders. About 70 percent of adults with social phobia suffer from chronic constipation. Up to 30 percent of people with panic disorder complain of being constipated. Other GI complaints associated with anxiety include reflux disease, lactose intolerance and IBS. People who have experienced trauma may develop post-traumatic stress disorder (PTSD). Trauma survivors are four times more likely to have PTSD than non-traumatized people. Studies suggest that exposure to emotional stress can alter the structure of the gut microbiome.
Long-term psychological stress can also impair digestion by decreasing gastric motility and interfering with the secretion of acid and enzymes needed to break down food.
It’s possible that anxiety could also directly impact the gut microbiome. Researchers believe that stress decreases the amount of beneficial gut bacteria while promoting harmful bacteria. Harmful bacteria can damage the lining of the intestine and prevent nutrients from absorbing properly. This could explain why anxiety can lead to fatigue, malnutrition and weight gain.
Another theory proposes that the gut microbiome can influence the development and severity of anxiety disorders. Scientists think that the gut microbiome communicates with the central nervous system via the vagus nerve. This nerve runs right down the middle of the abdomen and connects the brain stem to the belly. Recent research shows that the gut microbiome can affect the function of the vagus nerve. Specifically, mice whose microbiomes had low diversity showed higher activation of the vagus nerve compared to mice with diverse microbiomes.
Mice lacking MyD88, a protein necessary for signaling within the innate immune system, also exhibited altered responses to vagus nerve stimulation. Based on this evidence, scientists have hypothesized that the gut microbiome can affect the activity of the vagus nerve and thus mediate communication between the central nervous system and the enteric nervous system (the network consisting of the small and large intestine). This could mean that changes in gut microbiota can indirectly influence the brain and vice versa.
For now, it seems clear that anxiety can cause nausea. Understanding how anxiety influences the gut microbiome could eventually yield treatments that target both conditions. Until then, take comfort knowing that most GI issues associated with anxiety disappear within weeks of treatment. Most doctors recommend taking antidiarrheal medications (like loperamide) during acute episodes of dyspepsia. Antidepressants and benzodiazepines (such as diazepam) can also be used to treat dyspepsia. Patients should also consider trying dietary interventions.
Avoiding spicy and fried foods that contain trans-fats and sodium can help reduce bloating and indigestion. Eating plenty of fruits and vegetables can boost nutrient absorption and promote healthy digestion. Stomach distention can also be relieved by drinking lots of fluids (especially water) throughout the day. Finally, try to get regular exercise. Exercise promotes good circulation and reduces stress levels. Research suggests that physical activity can restore the balance of gut microbes disrupted by stress.
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