Yes! You’ve heard of the saying, “An apple a day keeps the doctor away!” But, if you experience constipation, the advice can be changed to “Two kiwis a day keeps the doctor away!”

The research study

Research published in the American Journal of Gastroenterology studied two groups of adults with either functional constipation or IBS-C (Irritable Bowel Syndrome – constipation predominant). The adults were randomly assigned to eat 2 green kiwis every day or 7.5 grams of psyllium powder every day for 4 weeks. Psyllium is a type of soluble fibre known to help alleviate constipation as well as reduce blood cholesterol levels. The amount of fibre from the kiwis and psyllium was the same – 6 grams.

After this 4 week period, both groups returned to their usual diets for 4 weeks. Then, the groups switched around and ate the other test food – in other words, the group that started off eating kiwis now ate psyllium every day for 4 weeks, and vice versa.

The results

Both kiwis and psyllium improved constipation. When eating kiwis, the participants experienced an increase of over 1.5 “complete spontaneous bowel movements” (CSBM) per week. As a reference, an increase of 1 or more CSBM per week is considered clinically relevant for improving constipation. Furthermore, kiwi eating participants reported less bloating and straining after eating kiwis when compared to psyllium.

How do kiwis work?

There are a couple of reasons why kiwis have this beneficial effect. For starters, the fibre in kiwis has a higher swelling and water holding capacity than other fruits. In fact, the swelling ability of kiwi fibre is more than 6 times higher than apple fibre! Since kiwis can help retain more water in the small intestines, this helps to increase bulk and soften the stools as well as increase stool frequency.

In addition, kiwis contain a special enzyme called actinidin which seems to speed up the digestion of proteins and keeps things moving in the gut for more regular bowel movements.

The bottom line

Kiwis (green or gold) can be a helpful food to help ease constipation. If your constipation is persistent, please contact a registered dietitian for specialized advice.

References:

Eltorki M, Leong R & Ratcliffe EM, 2022. Kiwifruit and kiwifruit extracts for treatment of constipation: a systematic review and meta-analysis. Can J Gastroenterology & Hepatology 2022, Oct 6:2022:7596920; doi: 10.1155/2022/7596920.

Gearry R, Fukudo  Shin, Giovanni B et al., 2023. Consumption of 2 green kiwifruits daily improves constipation and abdominal comfort—results of an international multicenter randomized controlled trial. The American Journal of Gastroenterology 118(6):p 105. doi: 10.14309/ajg.0000000000002124.

Wilkinson-Smith V, Dellschaft N, Ansell J et al., 2019. Mechanisms underlying effects of kiwifruit on intestinal function shown by MRI in healthy volunteers. Alimentary Pharmacology & Therapeutics, 2019 Jan 31;49(6):759-768. doi: 10.1111/apt.15127