Constipated? Here’s What Actually Works, According to Scientists

Just about everyone gets, ahem, backed up—aka, constipation—occasionally. For many people, however, constipation can turn into a constant nightmare. Thankfully, a handy evidence-based guide out this week highlights the foods and dietary supplements most likely to help you smooth out your bathroom trips.

Researchers in the UK compiled the guide, following an extensive review of the medical literature. Kiwis, rye bread, and fiber supplements were some of the items that had clear evidence supporting their use for chronic constipation, the researchers found. The conclusions, endorsed by the British Dietetic Association, represent the first rigorous dietary guidelines for managing this frustrating health condition, the authors say.

“Chronic constipation can have a huge impact on someone’s day-to-day life,” said lead author Eirini Dimidi, a nutrition researcher at King’s College London, in a statement from the university. “For the first time, we’ve provided direction on what dietary approaches could genuinely help, and which diet advice lacks evidence.”

A chronic issue

Estimates vary, but around 16% of the world’s population is thought to currently have constipation, while chronic constipation may affect between 9% and 20% of adults in the U.S. Constipation is also known to become more common as we age, affecting between a quarter and a third of people over 65.

Most cases of chronic constipation aren’t linked to a single known cause, such as a disease, but there are factors that raise the risk of it happening, including lifestyle habits like our diet.

Medical guidelines in the past have emphasized generalized tips for handling constipation, such as eating a diet rich in fiber. But the study researchers say their work is intended to pinpoint the specific foods and supplements that have the most scientific backing for treating constipation.

The researchers conducted four separate systematic reviews, which collectively analyzed data from 75 randomized and controlled clinical trials. The findings from this review were then used to create guidelines through an approach called the Grading of Recommendations, Assessment, Development and Evaluation, or GRADE, system.

One important aspect of the GRADE system is that it classifies the level of evidence supporting a particular recommendation as well as the strength of a recommendation, meaning how helpful it would be to people. A strong recommendation in this case, for instance, would mean that most everyone with chronic constipation would likely benefit from following it. The proposed recommendations were also evaluated and decided on by a panel of relevant experts in the field (this is known as a Delphi consensus).

The guidelines were jointly published in two journals, the Journal of Human Nutrition & Dietetics as well as Neurogastroenterology & Motility.

What works best for constipation?

All in all, the researchers came up with 59 recommendations.

The supplements most strongly recommended for constipation in the guidelines are psyllium fiber supplements, magnesium oxide supplements, and probiotics (though it’s still unclear which specific strains might be best).

As for specific foods, the list goes: kiwifruits, rye bread, and high-mineral water.

Interestingly, the authors failed to find sturdy enough evidence to support any whole diet approach, including high-fiber diets. While it’s still possible that eating lots of fiber could prevent or manage chronic constipation, the researchers say better-quality studies are needed to know for sure. It’s also worth noting that high-fiber diets are thought to have many health benefits, so there’s no reason to feel worried if you already include plenty of fiber in your meals.

The researchers argue more extensive research should still be done to suss out the optimal treatments or interventions for constipation, since many of the studies they reviewed were low quality. But as is, their recommendations can already help people dealing with constipation, they say.

“Being able to improve this condition through dietary changes would allow people to self-manage their symptoms more and, hopefully, improve their quality of life,” said Dimidi.