Two green kiwifruits a day, eaten for at least four weeks, may be one of the simplest ways to ease chronic constipation. That is the practical takeaway from the first British dietary guidelines dedicated to the condition, published in 2025 and built on evidence from 75 randomized controlled trials.
The guidelines were issued by the British Dietetic Association and drew on four systematic reviews and meta-analyses covering 75 RCTs in total. Kiwifruit came out as one of the few whole foods to earn a positive recommendation, alongside psyllium, rye bread, high-mineral water and certain probiotics.
Constipation is common, and it is not a fringe complaint. Systematic reviews estimate the worldwide prevalence in adults at roughly 16 percent, and it is one of the most frequent reasons people end up in a gastroenterologist's office.
What the pivotal trial actually found
The strongest single piece of evidence behind the recommendation is a multicenter randomized crossover trial published in June 2023 in the American Journal of Gastroenterology. Researchers in New Zealand, Japan and Italy assigned 184 people, including 60 with functional constipation and 61 with constipation-predominant IBS, to eat either 2 green kiwifruits or 7.5 grams of psyllium husk daily for four weeks, then swapped after a washout period.
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In both patient groups, kiwifruit produced an increase of at least 1.5 additional complete spontaneous bowel movements per week, a threshold the researchers had set in advance as clinically meaningful. When the two constipated groups were pooled, kiwifruit outperformed psyllium on that measure and also improved gut comfort more, without meaningful side effects.
A second trial found less straining
A 2022 randomized crossover trial from New Zealand, published in Nutrients, tested 2 gold kiwifruit a day against 7.5 grams of psyllium in 73 participants over a 16-week protocol. Both interventions improved constipation scores, but gold kiwifruit stood out on one specific outcome. It significantly reduced weekly straining episodes, while psyllium barely moved the needle on that measure.
A 2022 systematic review and meta-analysis that pooled 7 trials and 399 participants reached a compatible conclusion. For kiwifruit extracts compared with placebo, the pooled data pointed to a mean increase of about 1.36 weekly spontaneous bowel movements, though the confidence interval crossed zero and the authors rated the certainty of evidence as low. The whole-fruit trials in the review were compared with psyllium rather than placebo, and the authors called for larger, more rigorous studies.
Why the fruit may work
Kiwifruit is a modest source of fiber, roughly 2.4 grams in a green kiwi around 80 grams. What sets it apart, according to a review in Practical Gastroenterology, is an unusually high water-holding capacity that helps the fiber swell in the gut, plus a proteolytic enzyme called actinidin that appears to speed up how quickly food leaves the stomach. Together those effects may soften stool and shorten transit time.
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How to actually use it
The dose in the trials was two whole kiwifruit a day. Eating the fuzzy skin adds fiber for those who tolerate it. Give it four weeks before judging whether it helps, since that is the minimum duration the guidelines recommend.
People whose constipation is severe, sudden or accompanied by bleeding, unexplained weight loss or persistent pain should see a doctor rather than reach for fruit first.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.