Do bananas cause constipation? A dietitian answers.

You may be wondering, “Do bananas cause constipation?”. Unfortunately, different sources say different things thus leading to confusion.

Some people believe that bananas help to ‘thicken up’ stools, but others have suggested that they can cause adverse IBS symptoms –  such as diarrhea.

This post aims to explore this topic in detail. It will break down the science and provide an evidence-based answer to help you educate the naysayers.

Keep reading to discover the importance of bowel regularity and to understand whether bananas can impact it.

Are Bananas Low FODMAP?

Let’s start by looking at the FODMAP profile in bananas.

Bananas contain FODMAPs which may cause you bloating and loose stools if you have IBS, but not constipation.

For more information on the exact FODMAP content of bananas please see our other post “Banana FODMAP content”.

Resistant starch and constipation

Unripe bananas contain more resistant starch, which can increase stool transit time – which again would prevent constipation!

Resistant starch is a form of carbohydrate that is utilized in the large bowel and may act as a prebiotic and therefore may benefit a person’s gut microbiome (5).

However, this could result in abdominal bloating due to gas produced by the gut bacteria during this process and thus contribute to your IBS symptoms.

Also, it’s worth noting that a green banana is often considered less palatable than ripe bananas due to their flesh being firmer and less sweet.

How the fiber content of bananas helps with constipation

As bananas ripen, enzymes break down the resistant starch and the availability of water-soluble fiber increases – which helps to bulk out our stools (2, 3).

An average ripe banana contains ~ 5.3g of total dietary fiber, therefore bananas can be a great addition to help you meet the recommended 30g of dietary fiber per day (4)!

Given this fiber content, bananas are unlikely to cause you to experience constipation!

Whereas green bananas are low in FODMAPs but are high in resistant starch which may cause abdominal bloating.

Therefore, it may be best to opt for only slightly green bananas to both manage constipation but to limit any adverse IBS symptoms if you are more sensitive.

How can diet affect constipation?

If you suffer from constipation, you may not pass bowel movements daily. Your stools might be hard or lumpy and may be difficult or painful to pass (6).

There are many possible causes of constipation and medical conditions. For exampl IBS, coeliac disease and gastroparesis that can exacerbate symptoms of constipation (6).

The main dietary causes of constipation are not consuming enough fiber or fluid:

You should aim to consume ~30g fiber and at least 8 cups of water per day (may need to increase depending on individual needs) (7, 8) 

To understand more about ‘what is constipation and how can you treat it’ then check out our other blog post here. 

Summary

Bowel regularity is important for supporting bowel health; and a low fiber diet has been linked to increased occurrence of bowel cancer and cardiovascular mortality.

Bananas can be a great source of fiber and so are unlikely to cause constipation!

These resistant starches can produce gas in our large bowel and this may result in abdominal pain/bloating. 

As bananas ripen, the resistant starches are broken down and the availability of soluble fiber increases. However this also increases the fructans in the bananas!

Therefore to avoid adverse IBS symptoms, simply opt for only slightly green bananas.

But remember, that there is no ‘one-size-fits-all’ and symptoms may vary from person-to-person –  therefore monitor your symptoms closely!