Constipation is a common health problem.
It's characterized by irregular bowel movements and hard stools that are difficult to pass.
There are many causes of constipation, ranging from a poor diet to a lack of exercise.
Some claim that bananas cause constipation, while others say they help prevent it.
Which is true? This article takes a look at the evidence.
Fiber has long been claimed to help prevent and relieve constipation (, ).
It's thought to absorb water, helping stools stay large and soft. This helps improve the movement of the stool through your digestive tract ().
However, the evidence that fiber actually helps relieve constipation is conflicting and surprisingly weak, given how many health professionals recommend high fiber intake to their constipated patients (, 6).
Some studies indicate that soluble fiber can help relieve constipation. Others suggest that reducing dietary fiber may actually help in some cases (, ).
Whether increasing fiber intake helps relieve constipation seems to come down to the individual. The type of fiber you ingest may also matter.
Bottom Line: Bananas are a fairly good source of fiber, which may help with constipation for some people. However, the evidence on this is rather conflicting.
Resistant starch is a complex carb that has fiber-like properties.
It escapes digestion in the small intestine and ends up reaching the large intestine, where it feeds the friendly bacteria that reside there (9).
Feeding these bacteria is a good thing. They produce short-chain fats, which contribute to digestive health and have beneficial effects on metabolism ().
Before it ripens, a banana is almost entirely starch, which composes up to 70–80% of its dry weight. A large part of this starch is resistant starch.
As the banana ripens, the amount of starch and resistant starch decreases and is converted into sugars (11).
Resistant starch functions like soluble fiber, which can help with constipation ().
One study found that feeding constipated mice resistant starch from bananas sped up the movement of stools through their intestines ().
Lastly, it's worth noting that green bananas have been used to treat diarrhea in children and adults. These properties are attributed to the high content of resistant starch (, , ).
Bottom Line: The resistant starch in green bananas acts like soluble fiber, and has been used to treat constipation. It may also help reduce diarrhea.
Many articles on the internet claim bananas cause constipation. Studies haven't confirmed this, but some people believe they are a risk factor for constipation.
In one study, German researchers investigated the perceived effects of various food items on stool consistency. They surveyed three groups:
- IBS: 766 patients with IBS, where constipation was a major symptom.
- Constipation: 122 patients were constipated.
- Control: 200 healthy individuals served as the control group.
When the three groups were asked which foods or beverages caused constipation, bananas were mentioned by 29–48% of respondents.
In fact, only chocolate and white bread were named more often ().
Bottom Line: There is no strong evidence that bananas cause constipation, although one survey found that some people believe they do.
Most people tolerate bananas well, at least when consumed in moderation.
They improve digestive health and have prebiotic effects, feeding your friendly gut bacteria and stimulating their growth.
One study of 34 overweight women examined how eating bananas affected gut bacteria ().
After the subjects ate two bananas a day for two months, the researchers observed increases in beneficial bacteria called Bifidobacteria. However, the effect wasn't quite statistically significant.
What's more, the banana group reported improvements in digestive symptoms like bloating and stomach pain.
Bottom Line: Bananas can improve digestion. Some research shows they may also stimulate the growth of good bacteria.
The evidence suggests bananas tend to reduce constipation rather than cause it.
However, researchers have also found that some people think bananas make them constipated.
If you feel that bananas give you constipation, then simply eat fewer of them. If that doesn't work, try eliminating them from your diet completely to see if that helps.
At the end of the day, we're all different. A food that relieves constipation for you may have the opposite effect on someone else.