Research update: Kiwifruit, psyllium and prunes, which one is better for constipation?


Jimmy Lee - Research Dietitian, 12 November 2021

Chronic constipation is a condition that may present with a range of unpleasant abdominal symptoms for patients. One of the ways to achieve symptom relief is by using natural treatment options. A recent study compared the effectiveness of kiwifruit, psyllium and prunes in patients diagnosed with chronic constipation (1).

What is chronic constipation?

Chronic constipation can be broadly defined as ‘unsatisfactory defecation, characterised by infrequent stools, difficult stool passages, or both’ (2). It is a common gastrointestinal condition estimated to affect 7 to 14% of the global population (3, 4). Patients with chronic constipation often report the following symptoms:

-Reduced stool frequency

-Hard stool consistency

-A sensation of incomplete evacuation


According to the Rome IV criteria, chronic constipation is a spectrum that includes both functional constipation and IBS-C. The major difference between functional constipation and IBS-C is that patients with IBS-C present with severe abdominal pain.

2_01_spectrum of functional bowel disorders_infographic-01.jpg

Spectrum of functional bowel disorders. Pain is usually present in IBS-C but not functional constipation.

Why are we interested in the role of kiwifruit, psyllium and prunes in patients with chronic constipation?

In recent years, the use of natural treatment options for constipation relief has been gaining interest in the public. Prunes, psyllium and kiwifruit are natural options that have been used to treat chronic constipation in various areas of the world (5-8).

Although studies have affirmed their effectiveness in symptom relief in patients with constipation, there is currently no literature directly comparing the treatment efficacy of these three options. Therefore, this study sought to compare the effectiveness of kiwifruit, psyllium and prunes in alleviating symptoms in North American patients with chronic constipation (1).

What is this study about?

This study included adult participants who were diagnosed with either IBS-C or functional constipation. Patients undertook baseline screening during the first two weeks of the study to confirm their eligibility for this study before being randomised to consume one of the following treatments daily for four weeks:

-2 green kiwifruit, peeled

-100 g of prunes

-12 g of psyllium, in the form of Metamucil

Each type of treatment provided 6 grams of dietary fibre per day.

Per serve used in this study
Kiwifruit Serving size: 2 fruits

Energy: 359 KJ
Dietary fibre: 5 - 6 g
Carbohydrate: 14.2 g
Prunes Serving size: 100 g

Energy: 1450 KJ
Dietary fibre: 5 – 6 g
Carbohydrate: 80 g
Psyllium Serving size: 12 g

Energy: 189 KJ
Dietary fibre: 6 - 7g
Carbohydrate: 11 g

The nutrition composition of each type of treatment used in this study. Source of information: Foodworks 10.

Participants were observed for another two weeks after they had completed the 4-week treatment. Throughout the 8-week study, they were asked to record their gastrointestinal symptoms using an online symptom assessment tool. After the treatment period, they were also asked about their perception of symptom improvement and overall treatment satisfaction.

At the end of the study, 75 patients had completed all phases of the study.

What did the researchers find out?

The primary outcome of this study was the proportion of patients who reported an increase of 1 or more Complete Spontaneous Bowel Movement (CSBM) per week, for at least 2 of the four weeks of treatment. CSBM is defined as ‘a bowel movement without the use of laxatives that is associated with a sense of complete defecation’ (9). It is a means of measuring symptom relief in patients with chronic constipation and is often used in research studies (9). Despite those in the prunes group responding slightly better to treatment, all three groups were similar in terms of achieving their outcomes of increasing CSBM.

Stool frequency and consistency

Stool frequency, measured as the average number of CSBM per week, increased significantly for all three groups between weeks 3 to 4 of treatment and baseline. However, prunes showed the greatest improvement in stool frequency out of all three groups.

For stool consistency, participants in the kiwifruit and prunes groups improved significantly within their groups between weeks 3 to 4 and treatment, and they also produced greater changes in stool consistency compared to psyllium.

Straining and bowel movements with a sensation of incomplete evacuation

The average proportion of bowel movements with a sensation of incomplete evacuation decreased between weeks 3 to 4 of treatment and baseline within all groups. Prunes produced the greatest effect out of all three groups.

All three groups reported improvements in straining between baseline and weeks 3 to 4 of treatment. Although prunes produced the greatest improvements, changes were similar when compared between groups.

What do these treatment options mean for patients with chronic constipation?

The authors concluded that kiwifruit, psyllium and prunes improved constipation symptoms in participants. If you suffer from chronic constipation, you may like to consider the points below when selecting and following these treatment options.

Kiwifruit appears to be a safe and preferred method for alleviating symptoms. In this study, 68% of participants reported satisfaction with consuming kiwifruit. Not only are they rich in fibre, but they are also low in FODMAP in a serve of 2 fruits and packed with vitamin C, making them an enjoyable and nutritious option for managing constipation.

Psyllium is high in soluble fibre and is tolerated well by most IBS-C patients. However, a small number of individuals may experience bloating or distention. If you have been prescribed psyllium as a fibre supplement by your healthcare professional, it is important that you start with a small dose and titrate up to the prescribed dose. This allows the gut to adjust to the increased fibre intake and minimise the risk of symptom exacerbation.

Prunes are high in both fibre and sorbitol, and these components both promote laxation in people with constipation. However, sorbitol is also a FODMAP, and may trigger unpleasant symptoms in some people with IBS. For this reason, kiwifruit may be a better first choice for symptom relief in people with IBS-C. 

Nutritional benefits FODMAP content
Kiwifruit -Good water-holding capacity and high viscosity to help with stool softening and bulking

-Great vitamin C content
Low in FODMAP in 150 g (2 small fruits)
Prunes Contain both insoluble and soluble fibre: Increases stool volume

Sorbitol: Draws water into the small intestine, promoting laxation
High in sorbitol and fructans in 30 g (or 4 prunes)
Psyllium High in soluble fibre, which provides water-holding and gel-forming ability Appears to be tolerated by most people with IBS, but tolerance may vary

The nutritional benefits and FODMAP content of each type of treatment used in this study.


1. Chey SW, Chey WD, Jackson K, et al. Exploratory Comparative Effectiveness Trial of Green Kiwifruit, Psyllium, or Prunes in US Patients With Chronic Constipation. Am J Gastroenterol. 2021;116(6):1304-12.

2. Andrews CN, Storr M. The pathophysiology of chronic constipation. Can J Gastroenterol. 2011;25 Suppl B(Suppl B):16B-21B.

3. Suares NC, Ford AC. Prevalence of, and risk factors for, chronic idiopathic constipation in the community: systematic review and meta-analysis. Am J Gastroenterol. 2011;106(9):1582-91; quiz 1, 92.

4. Heidelbaugh JJ, Stelwagon M, Miller SA, et al. The spectrum of constipation-predominant irritable bowel syndrome and chronic idiopathic constipation: US survey assessing symptoms, care seeking, and disease burden. Am J Gastroenterol. 2015;110(4):580-7.

5. Eady SL, Wallace AJ, Butts CA, et al. The effect of 'Zesy002' kiwifruit (Actinidia chinensis var. chinensis) on gut health function: a randomised cross-over clinical trial. J Nutr Sci. 2019;8:e18-e.

6. Lever E, Scott SM, Louis P, et al. The effect of prunes on stool output, gut transit time and gastrointestinal microbiota: A randomised controlled trial. Clin Nutr. 2019;38(1):165-73.

7. Chang CC, Lin YT, Lu YT, et al. Kiwifruit improves bowel function in patients with irritable bowel syndrome with constipation. Asia Pac J Clin Nutr. 2010;19(4):451-7.

8. Attaluri A, Donahoe R, Valestin J, et al. Randomised clinical trial: dried plums (prunes) vs. psyllium for constipation. Aliment Pharmacol Ther. 2011;33(7):822-8.

9. Johnston JM, Dougall JM, Lavins BJ, et al. Complete Spontaneous Bowel Movement Frequency as Primary Outcome Measure in Patients with Chronic Constipation Treated with Linaclotide: 1078. Official journal of the American College of Gastroenterology | ACG. 2007;102:S513.

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