Gastrocolic reflex: In IBS, causes, symptoms, when to seek medical attention

Ever wonder why you suddenly need to use the bathroom soon after a meal? There is a scientific reason for this: the gastrocolic reflex.

Picture of a tissue paper roll on a silver holder

Key takeaway:

  • The gastrocolic reflex is a normal part of the digestive process, and it is more active in the morning.
  • Gastrocolic reflex may be heightened in people with irritable bowel syndrome.
  • Infants have a more active gastrocolic reflex.

Have you ever experienced the feeling of needing to use the bathroom right after finishing a meal? 

This sensation might lead you to believe your food is not being digested properly, and some people may even describe it as "food going right through them."

This common occurrence is known as the gastrocolic reflex, a natural reflex that occurs in the digestive system after food intake. 

This article will explain what a gastrocolic reflex is, its causes and symptoms, and how to manage an overreactive gastrocolic reflex. To learn more about the gastrocolic reflex, continue reading. 

What is the gastrocolic reflex?

The gastrocolic reflex is a physiological reflex that controls the movement of the lower gastrointestinal tract after eating. 

It is important to know that the gastrocolic reflex is neither a disease nor an abnormality but rather a natural process the body undergoes following a meal.

After eating, the body activates a reflex called the gastrocolic reflex, which increases the movement in the colon to make room for more food.  

The gastrocolic reflex is most active in the morning and after eating a meal. It is also more active in people who have irritable bowel syndrome (IBS)

When the gastrocolic reflex is functioning correctly, it is simply your body's way of signaling the colon to make room for more food. 

What causes gastrocolic reflexes?

The exact mechanism of the gastrocolic reflex is not fully understood. However, this reflex action is known to occur in response to the presence of food in the stomach.

The gastrocolic reflex is activated by stretch receptors, neuropeptides, and the enteric nervous system in response to the presence of food in the stomach.

The large intestine also uses strong, frequent contractions called mass movements, which are controlled by the enteric nervous system to help move food toward the rectum for defecation, causing the urge to go to the toilet after a meal.

Factors that increase the gastrocolic reflex

Some factors that can increase gastrocolic reflex include:

  • Eating a large meal
  • Eating foods high in fat or fiber 
  • Stress and anxiety
  • Consuming caffeine 
  • Consuming foods or beverages containing lactose (if you are lactose intolerant)

Causes of an overactive gastrocolic reflex

Although the gastrocolic reflex is a normal part of the digestive process, in some people, this reflex can be overactive and exaggerated. 

The exact cause of an overactive reflex is unknown. However, changes in the gut microbiome could lead to modifications in the movement of the colon, causing symptoms. For instance, dietary shifts to foods high in fat, animal protein, and sugar may contribute to an imbalance in the gut microbiome. This can worsen IBS symptoms.

In addition, an exaggerated gastrocolic reflex response to meals may result from abnormal levels of the hormones cholecystokinin (CCK) and motilin that regulate movement in the digestive tract.

Motilin and cholecystokinin have a stimulating effect on the small intestine and colon motility. If these hormones are in excess or disturbed, they can lead to diarrhea or frequent bowel movements. Medications like antibiotics or foods rich in fat can trigger the release of these hormones.

Overreactive gastrocolic reflex has been suspected as the cause or part of the cause of irritable bowel syndrome.

IBS is a functional gastrointestinal disorder characterized by recurring abdominal pain, discomfort, bloating, and changes in bowel habits. 

Research suggests that patients with IBS show a stronger colonic response to the gastrocolic reflex, which may worsen their symptoms.

A common symptom of patients with IBS is the need to use the bathroom after eating. In addition, these patients often feel relief from symptoms like abdominal pain or bloating after defecation. This phenomenon is believed to happen, at least in part, due to an overreactive gastrocolic reflex. 

Is gastrocolic reflex common in infants?

Yes, a gastrocolic reflex is common in infants. Newborns often have an active gastrocolic reflex which may cause them to have a bowel movement immediately after eating or even while eating. 

This reflex is usually more active in the first few weeks of life. However, the gastrocolic reflex becomes less active over time, and bowel movements become less frequent.

It is important to understand that an active gastrocolic reflex in infants is normal. In an observational study conducted in daycare centers to evaluate the gastrocolic response in healthy toddlers, researchers discovered that half of the children defecated, and 70% did so within half an hour after finishing a meal.

Symptoms of an overreactive gastrocolic reflex

  • Abdominal pain
  • Cramps
  • Bloating
  • Sudden urge to move the bowels
  • Diarrhea 
  • Flatulence (gas)

How do you treat an overreactive gastrocolic reflex?

If you notice your gastrocolic reflex is heightened after eating certain meals or beverages, then it can help to limit your intake of such foods or avoid them if you can. It also helps to eat smaller meals and avoid fatty, greasy, or fried food.

Peppermint oil has also been found to be safe and effective in reducing the pain and symptoms that accompany IBS. So, drinking peppermint tea or taking peppermint oil supplements may help ease the symptoms of an overactive reflex.

Medications are also helpful in calming an overactive gastrocolic reflex in people with IBS. Commonly prescribed medications include antispasmodics (hyoscyamine), and antiemetics (ondansetron).

Doctors may also prescribe antibiotics and probiotics to help restore normal colonic flora. A review of over 30 studies conducted by the American College of Gastroenterology has found that probiotics may help improve symptoms such as bloating and flatulence in people with IBS.

When to contact a doctor

Having the urge to go to the bathroom after eating does not usually require going to the hospital. However, if you notice that your symptoms related to an overactive gastrocolic reflex last more than a few days or are very severe and frequent, contact a doctor. They may be able to help identify the cause of your heightened gastrocolic reflex and recommend treatment to help you manage your symptoms.