Serotonin and IBS : The Brain-Stomach Link

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What is IBS?

Irritable bowel syndrome or IBS is a set of symptoms that affect your gastrointestinal tract. It primarily affects your large intestine. A common gastrointestinal disorder, it has three types: IBS with diarrhea predominance (IBS – D), IBS with constipation predominance (IBS – C), and IBS with mixed diarrhea/constipation (IBS – M). 

IBS significantly impacts a person’s life and can interfere with their social life, mental health, career, and education. While symptoms of IBS may be minor in some people, they can be very significant in others.

Symptoms of IBS include – 

  • Abdominal pain or cramping, generally in the lower half of the abdomen
  • Bloating
  • Gas
  • Harder or looser than usual bowel movements
  • Diarrhea
  • Constipation
  • Mucus in stools

Symptoms of IBS may flare up in women during their menstrual cycle. 

Though the actual cause of IBS is still unclear, studies suggest that it can be linked to an overly sensitive immune system or colon. Certain studies also suggest that changes in your hormones, especially serotonin, might directly relate to flare-ups of IBS.

What Is Serotonin?

Serotonin is a hormone that acts as a monoamine neurotransmitter. It means that it carries messages from the nerve cells in our brain to different parts of our body that tell our body how to function.

Serotonin plays a key role in managing sleep, mood, digestion, nausea, bone health, healing wounds, and blood clotting. Conversely, low or high serotonin levels can cause several health problems, both physical and psychological.

Did you know that most of the serotonin is found in your gut? So, the different mood swings you feel through the day – the butterflies you feel in your stomach when nervous or feeling like peeing when you’re scared or the instincts you get that help you make decisions which you term “going with your gut” – are functions of serotonin in your gut. 

About 90% of the serotonin found in your body is in the cells lining your gastrointestinal tract. Only about 10% of serotonin is produced in your brain!

How Do Ibs Affect Serotonin Levels And Vice Versa?

Serotonin plays a critical role in establishing contact between your brain and your gut while aiding the proper gut functioning.

With gut functioning, serotonin has some particular jobs like

  • Tracking motility of food through the GI system
  • Monitoring how much mucus is secreted in your intestines
  • Tracking the sensitivity of your intestines to pain sensations or the feeling of fullness
  • Feeling nausea or bloating

People with IBS – C usually have lower serotonin levels, meaning that the muscles in their rectum do not react as much to the signals sent by serotonin. As a result, it leads to hard, lumpy, or painful stools.

On the other hand, people with IBS – D have higher serotonin levels, meaning their rectum is hyperreactive and leads to watery and loose stools. 

Lower serotonin levels can affect your sleep patterns and are also associated with chronic depression and anxiety disorders. Serotonin may also cause significant emotional shifts in people coping with IBS.

Do Women’s Hormones Affect IBS and Serotonin?

Even though the cause of IBS is mostly considered idiopathic, there is one certainty in its study: The occurrence of IBS is twice as likely in women as it is in men. It is mainly due to estrogen and progesterone. They tend to trigger symptoms of IBS and cause more flare-ups, especially during periods.

Here’s how estrogen and progesterone affect IBS symptoms: These hormones affect your intestines’ function and how much pain you are supposed to feel. It is because the cells in your gut have these hormones attached to them through the help of receptors, making it easier for the gut to sense them and react to them.

Estrogen and progesterone affect IBS mainly through commanding

  • Digestion
  • Pain levels
  • Inflammation

Because levels of estrogen and progesterone rise and fall through the month, they are likely to affect symptoms of IBS. IBS is said to worsen as the stories of these hormones fall. A study indicates that 40% of women with IBS have been affected with symptoms of IBS during their menstrual cycles. Proper research and awareness is the key to women’s healthy life and proper management of their symptoms.

How Do You Manage IBS and Maintain Healthy Serotonin Levels?

Symptoms of IBS can irritate your mind and make you feel anxious, annoyed, angry, or downright depressed. These negative emotions harm you and only help flare up your IBS symptoms. By this logic, feeling the opposite, i.e., letting positive thoughts flood your mind, can help ease the symptoms of IBS.

Specific behavioral medicine treatments that can ease IBS symptoms and maintain healthy serotonin levels are – 

  1. Relaxation therapy: Relaxation therapy helps relax your muscles, calm your body, and aid in better sleep. All these factors boost healing and help release endorphins, also known as your body’s natural painkiller.
  2. Cognitive behavioral therapy: Changing your thoughts and behavior can automatically make your body react positively in stressful situations and lead to a healthier gut.
  3. Biofeedback: This technique involves taking charge of your body functions, including managing your hand temperature, breathing, and heart rate. It can help you relax and slow your heart rate in stressful situations.

Apart from behavioral changes that can manage your IBS and serotonin, there are other measures you can take to keep your IBS under check. For example: 

  • Making dietary changes; adopting the low FODMAP diet
  • Increasing physical activities
  • IBS medications


A direct connection between your brain and your belly can worsen your IBS symptoms. IBS also plays a huge role in managing serotonin levels in our body. Therefore, you must consult your doctor if you feel like your IBS symptoms or your mental health symptoms are worsening and get treatment immediately to cope better.

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