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The Brain-Gut Connection

nervous stomach symptoms

How does it feel when you have a presentation in front of a large audience? If you have stage fright, you probably start feeling nauseous or like all your intestines are knotted up. What about when you see someone you’re romantically interested in? The feeling is described as having butterflies in your stomach. How about when you see something that makes you sad and helpless? It feels gut-wrenching.

Do you notice the common theme amongst all these phrases? All these emotions you feel regularly instigate a reaction in your gut. Why is that so?

The truth is that it’s not all in your head! Your psychology directly influences chemical pathways and biological processes that affect your gut.

How are the gut and brain connected?

So, how does the magic really happen? Your digestive canal spans from your mouth to your esophagus to your rectum. There are two thin layers of 100 million nerve cells lining this canal, called the enteric nervous system (ENS). The ENS is part of the nervous system, but because it is such an extensive network and relies on the same neurotransmitters and types of neurons as the central nervous system (CNS), it is called your ‘second brain’. This network is closely connected to the CNS; so, when you feel ill in the stomach, you may also experience a headache. This communication between the brain and the gut is called the gut-brain axis.

The vagus nerve, running from the brain to the gut, is a very important connection between the two organs. It enables you to convert food to feelings. When you wake up in the morning and eat your breakfast, you feel satisfaction in your stomach and head. This is because your intestines are covered in a layer of villi. These villi are like small tiny hair and are made up of many different kinds of cells, mainly the enteroendocrine cell, which is also known as the gut sensor. Our gut sensor is connected to the vagus nerve.

We now know that the gut and the brain have an established connection. After the food particles come in contact with the sensor, they sense the chemical stimuli such as the nutrients. Then the signal is converted into electrical pulses and transmitted through a link of the vagus nerve. Through this sensory information, the brain and gut are interlinked. This connection influences the brain’s function within seconds, thus satisfying our hunger.

How does the gut microbiome affect mental health?

So, what else may influence the gut-brain axis? Researchers are also looking into the natural flora of the human body and how an imbalance in the healthy and unhealthy bacteria can affect the body. Normally, the human body contains thousands of ‘good’ bacteria in the skin, gut, and mucosal lining, which maintain a symbiotic relationship and prevent the growth of ‘bad’ bacteria. The microbiome of your gut is believed to play an important role in the health of the gut, obesity, and inflammatory skin disorders. However, research now suggests that this extends to the well-being of your brain and neurological systems, too.

If an imbalance of bacteria develops in the gut, the body’s immune system may overreact, leading to inflammation of the gastrointestinal (GI) tract. As a result of inflammation, disease symptoms will develop throughout the body, including the brain.

But could gut microbes be affecting physiological stress levels? The most recent study found it to be true among mice. When mice were exposed to certain microbes, they showed dramatic changes in brain levels.

For the study, scientists used germ-free mice: mice that were born and immediately placed in a clean cage, so that they were barely exposed to any microbes at all. These were compared to mice that were exposed to a known set of microbes. The experiment concluded that the germ-free mice got a lot more stressed out when they were restrained. So, it seemed like something about the bacteria in the mice was helping keep their stress level in check.

Gastrointestinal Disorders

The team found out that the brains of the germ-free mice had less activation in the brain regions that determine how an animal reacts to stress. This research proves that your gut does seem to affect your brain, but scientists aren’t 100% sure why this happens.

Disorders of the gut-brain axis

Nervous stomach

Often you have a nervous stomach and no lab tests can confirm the condition and no doctor can officially diagnose you with the problem. In this condition, you may experience some digestive problems due to a nervous or anxious state of mind.

Symptoms of the nervous stomach include:
  • Bloating
  • Frequent flatulence
  • Diarrhea
  • Nausea, queasiness
  • Increased urination
  • Indigestion or feeling of fullness after eating little food

These symptoms are similar to those of Irritable bowel syndrome (IBS). However, there are known physiological causes of IBS whereas a nervous stomach is mostly due to mental stress.

You may experience these symptoms in daunting situations when you feel nervous, like before a presentation or when having to confront someone.

Abdominal migraine

Did you know that migraines aren’t just constrained to the head? You may also experience abdominal migraines. An intense stomachache that may persist for hours or days on end can be triggered by anxiety, stress, and certain foods. It is more common in children but may present in adults as well. Over-thinking a stress-inducing topic is usually the cause of this condition in adults. There are no diagnostic tests to determine abdominal migraine; all lab tests seem to be clear.

Symptoms include:
  • Stomachache, originating around the belly button
  • Nausea
  • Vomiting

Headache due to digestive problems

Not only does research suggest that digestive issues may cause headaches, but statistics also suggest the opposite: i.e., headaches causing digestive problems. It’s kind of a casualty dilemma, or a chicken-and-the-egg problem, where we aren’t sure which comes first.

A migraine affects the brain and brainstem. Since the GI tract is directly connected to the brain, this channel of communication may cause symptoms to occur in the stomach. We do see nausea and vomiting as associated symptoms of migraine attacks.

Research suggests that people with frequent headaches may be more likely to develop gastrointestinal disorders. This is also true in the reverse scenario: people who suffer from GI problems such as diarrhea, constipation, acid reflux, are predisposed to also experience headaches.

Research has shown that people who regularly experience gastrointestinal symptoms such as diarrhea, constipation, and nausea, have a higher prevalence of headaches than those who don’t. The vagus nerve may be held responsible for this phenomenon since it links both the brain and gut together so that one triggers the other.

A digestive problem headache is also called a gastric headache and has the following symptoms:

  • Headache
  • Acid reflux
  • Indigestion
  • Abdominal pain or bloating
  • Bloating
  • Nausea or vomiting
  • Diarrhea

See Also: What’s The Difference Between ADD And ADHD?

The bottom line

We know that the gut-brain axis is a well-connected channel and issues in any one of the organs may affect the other.

If you suffer from any of the above issues, such as experiencing nervous stomach symptoms, or have noticed a connection between your headache and digestive problems, you can take over-the-counter medications and home remedies to treat the condition. However, lifestyle changes may also be required to wholly avoid the predicament. In any case, it is strongly advised to get in touch with your physician for a proper diagnosis and treatment plan.

Family Medicine Austin

Written by Jeannette

I am Jeannette, the medical writing specialist here at Family Medicine Austin. I have over five years of experience working with a range of medical and healthcare across the U.S.