The laxative effect of kiwifruit

Patel, Minaxi
Rush, Elaine
Ferguson, Lynnette
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Master of Applied Science
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Auckland University of Technology


Whole fruits, grains and vegetables contain thousands of potential disease-fighting, healthpromoting nutrients. These foods play a critical role in bowel function, especially in the elderly. Strong epidemiological evidence has shown that greater amounts of crude dietary fibre are associated with a lesser prevalence of constipation and other gastrointestinal disorders. Constipation usually presents as a variety of symptoms, including reduced frequency of defaecation and impacted forms of stools and/or increased effort required to defaecate. Constipation is a problem that could affect any person at any time in his or her life, but in the elderly is more prevalent. Although anecdotal reports and dietary advice have suggested the use of kiwifruit as a laxative in humans, there are, at present no data available to support this. Kiwifruit is reported as the most nutrient-rich of the top 27 fruits eaten in the world today. The laxative property of kiwifruit could provide a natural remedy for constipation and would be cheaper than the laxatives on the market.

Objective: The main objective of this study was to investigate if kiwifruit can act as a laxative, especially in elderly people.

Study Design and Methods: This study was carried out in two stages, as a pilot and then a main study. In the pilot study, 71 participants (aged 18 – 50y) were divided into Group I and Group II. Group I made no changes to their normal diet for a six weeks period, while Group II were asked to add one kiwifruit for every 30kg body weight per day to their diet for a six week period. After the six weeks, the two experimental groups crossed over, maintaining the dietary regime followed by the other group for a further six weeks. So each subject was his or her own control. Daily recording of the frequency and characteristics of the stool were made by the participants in a diary.

In the main study, 42 participants (aged 60 years and over) carried out the same dietary regime as the pilot study subjects. Elderly subjects of Group I made no changes to their diet, but was asked to record their daily frequency and characteristics of their stool for 3 weeks. Group II subjects ate one kiwifruit for every 30kg body weight per day for a period of 3weeks. After the three weeks period, the two groups crossed over.

Results: It was found from the pilot study that kiwifruit consumption was associated with significant softening of the stool (P<0.001); a significant increase in bulking of the stool (P=0.034) and the ease of bowel movement was improved (P<0.001). For the main study, kiwifruit consumption also showed softening of the stool (P<0.001) and the ease of bowel movement was improved (P<0.001), there was a slight but significant increase in bowel frequency (P=0.012) and the bulking of stool (P=0.002).

Conclusion: The results from this study provide evidence that consumption of kiwifruit enhances laxation and that bowel function can be improved through changes in diet, both for younger and elderly people.

Kiwifruit , Constipation , Laxatives , Older people , Fiber in human nutrition
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