What is the link between gluten and diarrhea?

Gluten.  This ingredient in bread, pasta, and baked goods makes many think of bloating and weight gain. However, this is not true for everyone. Gluten may not cause any symptoms in some individuals. However, in those with celiac disease, gluten could cause small intestinal damage. For those in between that spectrum, the non-celiac gluten sensitive, gluten could cause digestive symptoms similar to celiac disease, but without intestinal damage. Diarrhea, a symptom often linked with celiac disease, can occur after eating gluten. Let’s explore the reasons why gluten may cause diarrhea in those with celiac or non-celiac gluten sensitivity.

What is gluten?

Gluten is the protein found in wheat, barley, and rye that provides structure to foods like bread, pasta, and baked goods. It can also be found in processed foods like crackers, sauces, and convenience foods as a thickener or stabilizer for such foods.

Celiac disease vs. non-celiac gluten sensitivity

Celiac disease is a condition where the body views gluten as an invader. Because of this, whenever a person with celiac disease consumes gluten, the body goes into attack mode and triggers an immune response.  This leads to symptoms such as damage to the small intestine’s lining, and over time, this can lead to malabsorption of nutrients. This malabsorption can lead to anemia, or iron deficiency, while the intestinal damage can cause symptoms like fatigue, weight loss, bloating, and yes, diarrhea.

With non-celiac gluten sensitivity, people may have similar symptoms as that with celiac disease, but without the intestinal damage. Symptoms may include “foggy brain,” abdominal pain, bloating, diarrhea or constipation, as well as some mental health symptoms like depression or ADHD-like behavior.

Link between gluten and diarrhea

In autoimmune conditions like celiac disease, the body sees generally “safe” compounds as invaders in the body. In the case of celiac disease, when gluten enters the body, an immune response is triggered and over time can damage the intestine and cause malabsorption. It is thought that this malabsorption may be a contributing factor to the diarrhea observed in those with celiac disease.

For those with non-celiac gluten sensitivity, diarrhea may be caused by a variety of factors.

  • Low stomach acid can make it difficult for your gastrointestinal tract to fully digest the food you eat. This can lead to symptoms like diarrhea. Low stomach acid can be caused by stress, zinc or B vitamin deficiency, long-term use of medications like acid reflux treatments, as well as increased age.
  • Imbalance of gut bacteria can increase risk of gut infections, which in turn can increase risk of diarrhea. Taking antibiotics can kill off good bacteria and increase risk of gut bacteria imbalance. Other risk factors for gut bacteria imbalance include poor diet and low fiber intake. This is because fiber-rich foods like fruits and vegetables feed good bacteria in the gut and help them thrive. Taking a probiotic may be helpful in improving gut bacteria balance and in turn improve digestion. Also, consuming fermented foods like yogurt, sauerkraut, and kimchi can help improve gut bacteria balance in the gut. The only case where this approach would not be beneficial is if you have SIBO (small intestinal bacterial overgrowth) since the gut will already have too much bacteria in certain areas of the gut.
  • Food intolerances outside of gluten sensitivity can also cause diarrhea. For example, those with irritable bowel syndrome may be sensitive to gluten, but may also be just as sensitive to lactose, or milk sugar, fructose, as well as high-fat foods.  Therefore, cutting out just gluten in the diet will not be enough for such individuals to prevent diarrhea.  In this case, a food and symptom diary may be helpful to help the individual identify which foods and/or drinks cause symptoms.

Take home message

Diarrhea can be caused by many different digestive ailments. Therefore, there is no one-size-fits-all solution to this embarrassing and excruciating symptom. If you experience diarrhea and have tried cutting out certain foods already to no avail, it may be time for a visit to your healthcare provider to get tested to see what may be the cause so you can find a treatment that works.


Written by Staci Gulbin, MS, RD a Board-certified dietitian.

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