Can reintroducing FODMAPs help reduce constipation?

This idea might sound a bit counter-intuitive, right? After all, reducing FODMAPs is meant to help resolve Irritable Bowel Syndrome symptoms.  We often find that for people who suffer from constipation, the low FODMAP diet helps reduce bloating, cramps, abdominal pain and gas, but it may not completely resolve constipation. In fact, constipation issues can sometimes worsen on the low FODMAP diet, as the diet can be lower in fibre if you aren’t eating the right balance of foods (1).

So how can reintroducing FODMAPs help ease constipation…

FODMAPs are poorly absorbed in our small bowel, where they then have an osmotic effect that draws water into our intestines (2). Next, they are fermented by our gut bacteria in our large intestine and create gas (2). The combination of these two processes triggers IBS symptoms.

It’s the osmotic effect that can help reduce constipation. First, the increased amount of water in our intestines can increase the water content of our stools (3). The soluble fibre from the food we eat then acts like a sponge, which draws in the water, helping create stools that are larger and softer, therefore easier to pass (4, 5). Secondly, the osmotic effect helps food move through our digestive system faster and more easily, allowing FODMAPs to act like natural laxatives (2).

According to accredited practicing dietitian, Joanna Baker, for constipation sufferers, it’s this combination of increased speed and better formation of stools that can help ease constipation and make bowel movements more regular. The trick is figuring out which FODMAP groups you can tolerate without causing other symptoms.

What FODMAP groups might help relieve constipation?

Lactose, excess fructose and polyols (sorbitol and mannitol) all create an osmotic effect in our intestines and can act like natural laxatives (2, 6, 7). It is worth testing these groups to see if you can tolerate small amounts without triggering other symptoms.

How do you know when to start testing?

According to Joanna Baker, if your other gastrointestinal symptoms are now stable and constipation is your baseline symptom (the symptom that hasn’t improved during the low FODMAP phase), then you can look at moving into the reintroduction phase. You can monitor the success of your FODMAP challenge tests by tracking gas production, cramping, bloating, and abdominal pain, as well as the number of bowel movements or lack of bowel movements you produce. A FODMAP challenge is successful if it helps your constipation and doesn’t trigger other symptoms.

When challenging your high FODMAP foods you may find that you need to leave a day in between each portion of the challenge food, to monitor symptoms. This is because when you are constipated, food can take longer to reach your large intestine and trigger symptoms.

Final Thoughts

Constipation is a frustrating symptom to manage. It’s worth experimenting and attempting to reintroduce some high FODMAP foods back into your diet to see if their natural laxative effects can help. Otherwise check out our 12 tips for managing constipation for some other helpful strategies to relieve symptoms.