Can Eating Bananas Make You Constipated?

Medically reviewed by Kierra Brown, RD

Whether bananas contribute to or help constipation may depend on their level of ripeness. Unripe bananas have higher levels of tannins and resistant starch, compounds that may cause or aggravate pre-existing constipation.

Ripe bananas may help prevent or alleviate constipation due to their fiber content, as long as the person consumes adequate water. However, people with irritable bowel syndrome (IBS) may improve their symptoms, including constipation, by avoiding ripe bananas while following a low FODMAP diet.

How Diet Can Affect Constipation

Constipation is defined by having fewer than three bowel movements per week; stools that are hard, dry, or lumpy; stools that are difficult or painful to pass; or a feeling that not all stool has passed.

There are many possible causes of constipation. Taking certain medications and dietary supplements, as well as having medical conditions like irritable bowel syndrome (IBS), pelvic floor disorders, celiac disease, Parkinson’s disease, or hypothyroidism can all contribute to constipation.

The main dietary causes of constipation are not consuming enough fiber or liquids. Being physically inactive can also contribute to constipation.

When Do Bananas Cause Constipation?

Unripe or green bananas contain higher levels of tannins and resistant starch. Tannins inhibit peristalsis, the wave-like muscle contractions that move food through the digestive tract.

Resistant starch is a type of complex carbohydrate that is resistant to breakdown in the small intestine. Since the gut can't digest and absorb it into the bloodstream, resistant starch travels to the colon where it interacts with gut microbes.

This type of starch gets fermented in the colon, which generates compounds called short-chain fatty acids (SCFAs). SCFAs have been shown to reduce inflammation and improve insulin sensitivity (how well insulin works to clear sugar from the blood). Resistant starch also acts as a prebiotic, or food for beneficial probiotic gut bacteria, and has been shown to increase levels of beneficial microbes.

In short, resistant starch offers health benefits, which is why some people choose unripe bananas or green banana starch. However, the combination of tannins and resistant starch in unripe bananas may contribute to constipation or aggravate pre-existing constipation, particularly if too little fiber and fluid are consumed.

Can Bananas Relieve Constipation?

Ripe bananas contain both soluble and insoluble fiber, which can help prevent or manage constipation if adequate water is consumed. Soluble fiber attracts water within the gut and absorbs fluid to form a gel-like texture, which softens stool. Insoluble fiber doesn’t dissolve. It remains intact, adds bulk to stool, and helps food pass more quickly through the intestines.

Depending on age and sex, adults should consume about 22 to 34 grams (g) of total fiber each day to prevent constipation. Eight to 10 cups (2 to 2.5 liters) of liquids, particularly water, should also be consumed daily to prevent or relieve constipation.

How Else Do Bananas Affect Digestive Health?

Bananas are one of the four foods in the BRAT diet (bananas, rice, applesauce, and toast), which is sometimes recommended when people experience gastrointestinal symptoms, such as nausea and vomiting.

However, a bland diet has generally replaced BRAT for this purpose because it offers a wider variety and focuses on decreasing the amount of work required by the entire gastrointestinal system. Bananas are included as part of a bland diet.

In addition, bananas have been shown to help relieve an upset stomach by stimulating the production of mucus from the stomach lining. This creates a barrier between the stomach lining and acids that contribute to heartburn and stomach upset.

For people with IBS, banana ripeness also comes into play. A low FODMAP diet has been shown to be a safe and effective short-term approach to improve digestive symptoms in people with IBS.

FODMAPs (Fermentable Oligosaccharide, Disaccharide, Monosaccharide, and Polyols) are a group of sugars that are not completely digested or absorbed in your intestines. When FODMAPs reach the small intestine, they move slowly, and attract water, and when they pass into the large intestine, they are fermented by gut bacteria, which produces gas.

Studies have shown after following a low FODMAP diet up to 86% of patients with IBS experienced improvements in overall GI symptoms as well as individual symptoms, including abdominal pain, bloating, constipation, diarrhea, abdominal distention, and flatulence (gas).

One medium firm banana is considered a low FODMAP food. For ripe bananas, one-third of a medium banana qualifies as low FODMAP. Above this amount, the levels of one type of FODMAP called fructan start to increase. Therefore a medium ripe banana is considered a high FODMAP food.

However, people with IBS may be able to reintroduce ripe bananas without experiencing a return of symptoms as some types of FODMAPs may be better tolerated than others. This is tested through a systematic series of food challenges.

Overall, whether or not bananas support optimal digestive health may be situational. Bananas can support a healthy diet and potentially soothe an upset stomach, but they may or may not worsen IBS symptoms.

When to Contact a Healthcare Provider

If you have an upset stomach or constipation caused by an ongoing illness or chronic condition, talk with your personal healthcare provider about the consumption of bananas. If you have chronic constipation, consider working with a registered dietitian who can tailor a plan to your needs and guide you regarding bananas, fiber, fluid, and your overall diet.

If you are experiencing constipation along with any of the below symptoms, contact a healthcare provider immediately:

• Blood in your stool or coming from your rectum

• Stomach pain that doesn't go away

• Lower back pain

• Difficulty passing gas

• Vomiting

• Fever

• Unexpected weight loss

A Quick Review

Bananas may improve or worsen constipation depending on their level of ripeness; an unripe banana may worsen constipation while a ripe banana could relieve constipation.

These effects may also vary depending on a person's overall diet, including total intakes of fiber and fluid, and underlying health issues, like IBS. For people with IBS, eating a ripe banana may worsen their gastrointestinal symptoms while a firm banana is tolerable.

If you have recurring problems with constipation or have chronic constipation, talk to your healthcare provider about diet changes that may help.

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