Mechanisms underlying effects of kiwifruit on intestinal function shown by MRI in healthy volunteers

Abstract

Summary Background Chronic constipation affects approximately 17% of the population worldwide and remains an important unmet need since patients are often dissatisfied with treatment. Kiwifruit may offer an alternative to traditional laxatives and have been shown to increase stool volume, frequency and improve consistency. Aims Using non‐invasive MRI techniques, we assessed the effect of ingestion of kiwifruit on fluid distribution in the intestines and bowel function. Methods Two period crossover trial of kiwifruit vs control in healthy adults. Intervention: two kiwifruits twice daily vs isocaloric control (maltodextrin) twice daily, consumed for a total of 3 days. Subjects underwent MRI scanning fasted and at hourly intervals for 7 hours on the third day. Primary outcome: T1 relaxation time of ascending colon (T1AC) using MRI. Secondary outcomes: Small bowel water content (SBWC), colonic volume, gut transit time, T1 of descending colon, stool frequency and form. Results Fourteen volunteers completed the study. T1AC was higher after kiwifruit ingestion (P = 0.029) during the second half of the day (when meal residue would be expected to reach the AC, AUC T1 T240‐420 minutes; mean (SD) 137 (39) s*minute with kiwifruit versus 108 (40) s*minute with control. SBWC (P < 0.001), colon volumes (P = 0.004), as well as stool frequency (1.46 ± 0.66 with kiwifruit vs 1.14 ± 0.46 stools per day with control; P = 0.034) and stool form score (Bristol Stool Chart score 4.1 (0.9) with kiwifruit versus 3.4 (0.7) with control; P = 0.011) were markedly increased in participants consuming kiwifruit compared to control. Conclusion Consumption of kiwifruit in healthy volunteers increases water retention in the small bowel and ascending colon and increases total colonic volume. The data may explain the observed increase in stool frequency and looser stool consistencies, suggesting that kiwifruit could be used as a dietary alternative to laxatives in mild constipation.

The effect of green kiwifruit on gas transit and tolerance in healthy humans

“…Previous studies using radiopaque markers have shown that green kiwifruit accelerates whole gut transit time in patients with constipation and constipation‐predominant irritable bowel syndrome 2‐4 . In a recent study from Nottingham using MRI in healthy subjects, the authors found that ingestion of two green kiwifruits per day, the same intake as we used in the present study, produced an increment in water content in the small bowel and the ascending colon that could account for the increment in stool frequency and looser stool consistency observed 14 . However, in this study, the authors found the increment in colonic contents induced by kiwifruit, smaller than the increment induced by intake of psyllium in previous studies.…”

“…Previous studies from other laboratories have shown that psyllium and high‐calorie meals delay gas transit and evacuation 12,13 . In addition, trapping of gas by viscous material, as has been described for water after intake of a similar quantity of kiwifruit, 14 could delay gas transit and produce gas‐related abdominal symptoms. On the other hand, a prokinetic effect of kiwifruit 5 could accelerate transit and removal of intestinal gas, and thereby prevent gas‐related abdominal symptoms while improving constipation.…”

“…Previous studies from other laboratories have shown that psyllium and high-calorie meals delay gas transit and evacuation. 12,13 In addition, trapping of gas by viscous material, as has been described for water after intake of a similar quantity of kiwifruit, 14 could delay gas transit and produce gas-related abdominal symptoms.…”

MRI of the Colon in the Pharmaceutical Field: The Future before us

“…Respectively the T2 values in the ascending colon of the healthy group were 70 (56–72) ms, 73 (62–86) ms, and 83 (67–88) ms and T2 in the descending colon were 53 (40–67) ms, 54 (45–70) ms, and 74 (56–80) ms. The T2 of the patients’ ascending colon was 58 (42–73) ms on maltodextrin and 72 (51–105) ms on psyllium, while the respective values for the descending colon were 42 (34–52) ms and 66 (54–86) ms. Also, in a study of kiwifruit supplementation [32], the AUC (in seconds×minute units of measure) of the T1 constant of the ascending colon was 356 ± 109 on kiwifruit intervention and 291 ± 110 on control at time = 0–420 min whereas the AUC of the T1 from 240 to 420 min was 137 ± 39 and 108 ± 40, respectively. For the descending colon, the respective values were 216 ± 120 and 203 ± 114 from 0–420 min and 96 ± 50 and 87 ± 52 from 240–420 min.…”

Intraluminal Impact of Food: New Insights from MRI

“…Two kiwifruits taken twice daily demonstrate an immediate increase in small bowel water following consumption, which increases steadily throughout the day only falling after a second large meal which stimulates ileal emptying into the ascending colon. This was associated with a rise in ascending colon T1, indicating increased water content caused by increased inflow of ileal fluid [41].…”