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

BACKGROUND: Green kiwifruit is a fiber-rich fruit that has been shown effective for treatment of constipation. However, fermentation of fibers by colonic bacteria may worsen commonly associated gas-related abdominal symptoms. AIM: To determine the effect of green kiwifruit on transit and tolerance to intestinal gas in humans. METHODS: In 11 healthy individuals, two gas challenge tests were performed (a) after 2 weeks on a low-flatulogenic diet and daily intake of 2 green kiwifruits and (b) after 2 weeks on a similar diet without intake of kiwifruits. The gas challenge test consisted in continuous infusion of a mixture of gases into the jejunum at 12 mL/min for 2 hours while measuring rectal gas evacuation, abdominal symptoms, and abdominal distension. During the 2 weeks prior to each gas challenge test (on-kiwifruit and off-kiwifruit), the number and consistency of stools, and abdominal symptoms were registered. KEY RESULTS: Intake of kiwifruits was associated with more bowel movements per day (1.8 ± 0.1 vs 1.5 ± 0.1 off-kiwifruit; P = .001) and somewhat looser stools (Bristol score 3.3 ± 0.2 vs 2.8 ± 0.1 off-kiwifruit; P = .072) without relevant abdominal symptoms. Gas infusion produced similar gas evacuation (1238 ± 254 mL and 1172 ± 290 mL; P = .4355), perception of symptoms (score 1.2 ± 0.2 and 1.3 ± 0.3; P = .2367), and abdominal distension (17 ± 7 mm and 17 ± 6 mm; P = .4704) while on-kiwifruit or off-kiwifruit. CONCLUSIONS AND INFERENCES: In healthy subjects, green kiwifruit increases stool frequency without relevant effects on intestinal gas transit and tolerance. If confirmed in patients, these fruits may provide a natural and well-tolerated treatment alternative for constipation.

The nutritional and health attributes of kiwifruit: a review.

PURPOSE: To describe the nutritional and health attributes of kiwifruit and the benefits relating to improved nutritional status, digestive, immune and metabolic health. The review includes a brief history of green and gold varieties of kiwifruit from an ornamental curiosity from China in the 19th century to a crop of international economic importance in the 21st century; comparative data on their nutritional composition, particularly the high and distinctive amount of vitamin C; and an update on the latest available scientific evidence from well-designed and executed human studies on the multiple beneficial physiological effects. Of particular interest are the digestive benefits for healthy individuals as well as for those with constipation and other gastrointestinal disorders, including symptoms of irritable bowel syndrome. The mechanisms of action behind the gastrointestinal effects, such as changes in faecal (stool) consistency, decrease in transit time and reduction of abdominal discomfort, relate to the water retention capacity of kiwifruit fibre, favourable changes in the human colonic microbial community and primary metabolites, as well as the naturally present proteolytic enzyme actinidin, which aids protein digestion both in the stomach and the small intestine. The effects of kiwifruit on metabolic markers of cardiovascular disease and diabetes are also investigated, including studies on glucose and insulin balance, bodyweight maintenance and energy homeostasis. CONCLUSIONS: The increased research data and growing consumer awareness of the health benefits of kiwifruit provide logical motivation for their regular consumption as part of a balanced diet. Kiwifruit should be considered as part of a natural and effective dietary strategy to tackle some of the major health and wellness concerns around the world.

A Pilot Randomized Cross-Over Trial to Examine the Effect of Kiwifruit on Satiety and Measures of Gastric Comfort in Healthy Adult Males.

'Hayward' kiwifruit anecdotally are associated with improved gastrointestinal comfort following the consumption of high protein meals, possibly because of the presence of a protease enzyme, actinidin. The study aimed to use SmartPill™ technology to investigate the acute effect of kiwifruit with actinidin (Actinidia chinensis var. deliciosa 'Hayward') and kiwifruit without actinidin (A. chinensis var. chinensis 'Hort16A') on digestion of a large protein meal. Ten healthy male subjects were recruited. The participants attended the clinic three times, having fasted overnight. They consumed a test meal consisting of 400 g lean steak and two 'Hort16A' or two 'Hayward kiwifruit'. Subjects completed visual analogue scales (VAS) by rating feelings of hunger, satisfaction, fullness, and comfort and swallowed a SmartPill™ before completing further VAS scales. After 5 h, participants consumed an ad libitum lunch to assess satiety. SmartPill™ transponders were worn for five days. There were no significant differences in gastric emptying time, small bowel, or colonic transit time between the two kiwifruit arms of the study measured by SmartPill™. Similarly, no significant differences were observed in VAS satiety measures or energy consumption at the ad libitum meal. However, the measurement of overall gastric comfort tended to be lower, and bloating was significantly reduced following the consumption of the steak meal with 'Hayward' kiwifruit (p < 0.028). CONCLUSIONS: The SmartPill™ is marketed as a diagnostic tool for patients presenting with gastrointestinal disorders and is usually used with a standard 'SmartBar'. This small pilot study suggests that it is less likely to measure gastric emptying effectively following a high protein meal, as it may be delayed because of the meal's physical consistency. However, green kiwifruit, containing actinidin, may reduce bloating and other measures of gastric discomfort in healthy males. Possible future studies could use repeated measures with more readily digested protein and larger numbers of participants.

Kiwifruit-derived supplements increase stool frequency in healthy adults: a randomized, double-blind, placebo-controlled study.

The worldwide growth in the incidence of gastrointestinal disorders has created an immediate need to identify safe and effective interventions. In this randomized, double-blind, placebo-controlled study, we examined the effects of Actazin and Gold, kiwifruit-derived nutritional ingredients, on stool frequency, stool form, and gastrointestinal comfort in healthy and functionally constipated (Rome III criteria for C3 functional constipation) individuals. Using a crossover design, all participants consumed all 4 dietary interventions (Placebo, Actazin low dose [Actazin-L] [600 mg/day], Actazin high dose [Actazin-H] [2400 mg/day], and Gold [2400 mg/day]). Each intervention was taken for 28 days followed by a 14-day washout period between interventions. Participants recorded their daily bowel movements and well-being parameters in daily questionnaires. In the healthy cohort (n = 19), the Actazin-H (P = .014) and Gold (P = .009) interventions significantly increased the mean daily bowel movements compared with the washout. No significant differences were observed in stool form as determined by use of the Bristol stool scale. In a subgroup analysis of responders in the healthy cohort, Actazin-L (P = .005), Actazin-H (P < .001), and Gold (P = .001) consumption significantly increased the number of daily bowel movements by greater than 1 bowel movement per week. In the functionally constipated cohort (n = 9), there were no significant differences between interventions for bowel movements and the Bristol stool scale values or in the subsequent subgroup analysis of responders. This study demonstrated that Actazin and Gold produced clinically meaningful increases in bowel movements in healthy individuals.

No difference in fecal levels of bacteria or short chain fatty acids in humans, when consuming fruit juice beverages containing fruit fiber, fruit polyphenols, and their combination.

This study examined the effect of a Boysenberry beverage (750 mg polyphenols), an apple fiber beverage (7.5 g dietary fiber), and a Boysenberry plus apple fiber beverage (750 mg polyphenols plus 7.5 g dietary fiber) on gut health. Twenty-five individuals completed the study. The study was a placebo-controlled crossover study, where every individual consumed 1 of the 4 treatments in turn. Each treatment phase was 4-week long and was followed by a 2-week washout period. The trial beverages were 350 g taken in 2 doses every day (ie, 175 mL taken twice daily). The hypothesis for the study was that the combination of polyphenols and fiber would have a greater benefit on gut health than the placebo product or the fiber or polyphenols on their own. There were no differences in fecal levels of total bacteria, Bacteroides-Prevotella-Porphyromonas group, Bifidobacteriumspecies, Clostridium perfringens, or Lactobacillus species among any of the treatment groups. Fecal short chain fatty acid concentrations did not vary among treatment groups, although prostaglandin E2 concentrations were higher after consumption of the Boysenberry juice beverage. No significant differences were found in quantitative measures of gut health between the Boysenberry juice beverage, the apple fiber beverage, the Boysenberry juice plus apple fiber beverage, and the placebo beverage.

Influence of green and gold kiwifruit on indices of large bowel function in healthy rats.

The effects of kiwifruit on large bowel health were investigated in healthy rats. Four-week old Sprague-Dawley rats were given diets containing 10% homogenized green kiwifruit, gold kiwifruit or 10% glucose solution (control) over 4 or 6 wk. Green kiwifruit increased the fecal output compared to control. Growth of certain bacterial species in cecum was influenced by both green and gold kiwifruit. A significant increase in cecal Lachnospiraceae in rats fed the green kiwifruit diet was observed at week 4. At week 6, green and gold kiwifruit diets assisted in improving colonic barrier function by upregulating the expression of mucin (MUC)-2, MUC3, Toll-like receptor (TLR)-4 or trefoil factor-3 genes. Gold kiwifruit consumption increased the colonic goblet cells per crypt at week 6. Significant negative correlations between E. coli and ß-defensin 1 and TLR4 expression were observed. Consuming green and gold kiwifruit for 6 wk significantly altered the biomarkers of large bowel health; indicating that regularly consuming kiwifruit helps attain optimal digestive health.

Lactic acid bacteria convert glucosinolates to nitriles efficiently yet differently from enterobacteriaceae.

Glucosinolates from the genus Brassica can be converted into bioactive compounds known to induce phase II enzymes, which may decrease the risk of cancers. Conversion via hydrolysis is usually by the brassica enzyme myrosinase, which can be inactivated by cooking or storage. We examined the potential of three beneficial bacteria, Lactobacillus plantarum KW30, Lactococcus lactis subsp. lactis KF147, and Escherichia coli Nissle 1917, and known myrosinase-producer Enterobacter cloacae to catalyze the conversion of glucosinolates in broccoli extract. Enterobacteriaceae consumed on average 65% glucoiberin and 78% glucoraphanin, transforming them into glucoiberverin and glucoerucin, respectively, and small amounts of iberverin nitrile and erucin nitrile. The lactic acid bacteria did not accumulate reduced glucosinolates, consuming all at 30-33% and transforming these into iberverin nitrile, erucin nitrile, sulforaphane nitrile, and further unidentified metabolites. Adding beneficial bacteria to a glucosinolate-rich diet may increase glucosinolate transformation, thereby increasing host exposure to bioactives.

Modification of the colonic microbiota.

It is becoming clear that the ecology and functionality of the human gut microbiota are extremely diverse and complex. The microbiota have coevolved with us metabolically to live symbiotically and to share the workload of extracting nutrients and energy from the diet. It is also clear that a diet rich in fruit, vegetables, and whole grain cereals is good for general health and gut health and that this is due partly to the phytochemicals and partly to the nondigestible carbohydrates (or dietary fiber) that are present in plants. Kiwifruit contain polyphenolics and nondigestible carbohydrates in the form of pectic, hemicellulosic, and cellulosic polysaccharides, all of which can be degraded by various members of the gut microbiota and result in beneficial effects. This chapter summarizes how kiwifruit act to modify the colonic microbiota and the resultant beneficial effects on human health.

Digested and fermented green kiwifruit increases human ß-defensin 1 and 2 production in vitro.

The intestinal mucosa is constantly exposed to a variety of microbial species including commensals and pathogens, the latter leaving the host susceptible to infection. Antimicrobial peptides (AMP) are an important part of the first line of defense at mucosal surfaces. Human ß-defensins (HBD) are AMP expressed by colonic epithelial cells, which act as broad spectrum antimicrobials. This study explored the direct and indirect effects of green kiwifruit (KF) on human ß-defensin 1 and 2 (HBD-1 and 2) production by epithelial cells. In vitro digestion of KF pulp consisted of a simulated gastric and duodenal digestion, followed by colonic microbial fermentation using nine human faecal donors. Fermenta from individual donors was sterile filtered and independently added to epithelial cells prior to analysis of HBD protein production. KF products obtained from the gastric and duodenal digestion had no effect on the production of HBD-1 or 2 by epithelial cells, demonstrating that KF does not contain substances that directly modulate defensin production. However, when the digested KF products were further subjected to in vitro colonic fermentation, the fermentation products significantly up-regulated HBD-1 and 2 production by the same epithelial cells. We propose that this effect was predominantly mediated by the presence of short-chain fatty acids (SCFA) in the fermenta. Exposure of cells to purified SCFA confirmed this and HBD-1 and 2 production was up-regulated with acetate, propionate and butyrate. In conclusion, in vitro colonic fermentation of green kiwifruit digest appears to prime defense mechanisms in gut cells by enhancing the production of antimicrobial defensins.