Two green kiwis a day may ease constipation, review of 33 studies suggests

Eating two green kiwis a day could help people struggling with constipation, a new review suggests. The review, published in the journal Food, Nutrition and Health, looked at 33 earlier studies on kiwifruit and digestive health.

It found that eating two fresh green kiwis a day for about four weeks was linked to more regular bowel movements, less straining and better digestive comfort in people with constipation or irritable bowel syndrome with constipation (IBS-C).

In one international trial included in the review, people with constipation had about 1.5 more complete bowel movements per week, while those with IBS-C had about 1.7 more per week. Both groups also reported improved digestive comfort.

The review suggests there may be several reasons kiwi helps with constipation. Its fibre can add bulk and hold water in stool, while the fruit's natural water and sorbitol may help make stool easier to pass.

Researchers said the benefit likely comes from several parts of the whole fruit working together rather than from any one component alone.

Kiwi was not necessarily more effective than other constipation treatments, however. One US trial included in the review found that green kiwi, psyllium fibre and prunes all helped improve chronic constipation.

In that trial, kiwi was associated with fewer side effects and was well tolerated by many participants.

The evidence is strongest for fresh green kiwi, the researchers noted. There is less research on gold kiwi, powders and extracts, so those forms should not be assumed to have the same effect.

Jason Heiselman, a New York-based certified nutritionist and professional chef at Hungryroot, said kiwi is an easy fruit to work into a person's diet. In his words, including a few slices with any meal feels like a no-brainer. He was not involved in the new review.

Heiselman noted that kiwi contains fibre along with a natural enzyme called actinidin, which can help with digestion. Pairing kiwi with good fat sources, like seeds, nuts or full-fat dairy, allows the body to absorb more nutrients, he said.

For people who do not want to eat kiwi on its own, the fruit can also work in savoury meals, according to Heiselman. He said raw kiwi slices often make their way to his dinner table, paired with salty cheeses, toasted pistachios and shaved red onion, and he has also used kiwi as the base for chutneys and relishes.

There were some limitations to the findings. The paper reviewed previous research rather than conducting a new clinical trial, and the studies differed in the people involved, the types and amounts of kiwi consumed, and the results researchers measured.

Most of the research also looked at relatively short periods of time, so more studies are needed to determine whether the benefits continue over the long term, the researchers said.