Encapsulated green kiwifruit extract: a randomised controlled trial investigating alleviation of constipation in otherwise healthy adults

Objectives: Previous clinical trials have shown bowel function is improved through consumption of whole kiwifruit (Actinidia deliciosa). This study investigated whether encapsulated kiwifruit extract (1 g/day) could alleviate constipation in otherwise healthy adults. Methods: Forty adults with confirmed constipation entered this trial, of which 32 completed with ＞80% compliance. Two capsules were self-administered morning and evening for 2 periods, each of 3 weeks duration, separated by a 3 + week washout in a double blind, randomised, placebo controlled crossover. Inclusion criteria included constipation with ≤ 3 bowel movements (BM) per week. Daily records of defecation frequency and stool characteristics were obtained throughout treatment, as well as a measurement of gastrointestinal symptoms rating scale (GSRS) and quality of life (QoL) before and after each intervention arm. Results: There was no difference in total BM over 3 weeks (p ＞ 0.05) or mean BM during each of weeks 1, 2 and 3 (p ＞ 0.05) between the kiwifruit extract and placebo when assessed from a faecal diary. There was also no detectable difference in defecation related scores of BM ease of defecation, volume, consistency or BM type assessed using Bristol stool chart scores. Nor was there a significant change in GSRS or QoL between pre and post treatment measures, when compared to placebo (p ＞ 0.05). Conclusions: This trial showed that improvement in bowel function or comfort was not achieved through supplementation with 1 g/day freeze dried kiwifruit extract. Efficacy from prior kiwifruit powder and whole fruit trials indicate that investigating higher doses of encapsulated kiwifruit extract may be worthwhile.