Consumption of 2 Green Kiwifruits Daily Improves Constipation and Abdominal Comfort-Results of an International Multicenter Randomized Controlled Trial.

INTRODUCTION: Consumption of green kiwifruit is known to relieve constipation. Previous studies have also reported improvements in gastrointestinal (GI) comfort. We investigated the effect of consuming green kiwifruit on GI function and comfort. METHODS: Participants included healthy controls (n = 63), patients with functional constipation (FC, n = 60), and patients with constipation-predominant irritable bowel syndrome (IBS-C, n = 61) randomly assigned to consume 2 green kiwifruits or psyllium (7.5 g) per day for 4 weeks, followed by a 4-week washout, and then the other treatment for 4 weeks. The primary outcome was the number of complete spontaneous bowel movements (CSBM) per week. Secondary outcomes included GI comfort which was measured using the GI symptom rating scale, a validated instrument. Data (intent-to-treat) were analyzed as difference from baseline using repeated measures analysis of variance suitable for AB/BA crossover design. RESULTS: Consumption of green kiwifruit was associated with a clinically relevant increase of ≥ 1.5 CSBM per week (FC; 1.53, P < 0.0001, IBS-C; 1.73, P = 0.0003) and significantly improved measures of GI comfort (GI symptom rating scale total score) in constipated participants (FC, P < 0.0001; IBS-C, P < 0.0001). No significant adverse events were observed. DISCUSSION: This study provides original evidence that the consumption of a fresh whole fruit has demonstrated clinically relevant increases in CSBM and improved measures of GI comfort in constipated populations. Green kiwifruits are a suitable dietary treatment for relief of constipation and associated GI comfort.

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 effect of 'Zesy002' kiwifruit (Actinidia chinensis var. chinensis) on gut health function: a randomised cross-over clinical trial.

Functional gastrointestinal disorders including constipation affect up to 14 % of the world's population. Treatment is difficult and challenging resulting in a need for alternative safe and effective therapies. The present study investigated whether daily consumption of three gold-fleshed kiwifruit could alleviate constipation and improve gastrointestinal discomfort in mildly constipated individuals with and without pain. A total of thirty-two participants were enrolled in a 16-week randomised, single-blind, crossover study. Participants received either three 'Zesy002' kiwifruit or 14·75 g Metamucil® (5 g dietary fibre/d (a positive control)) for 4 weeks each with a 4-week washout between treatments. A 2-week washout period was included at the beginning and end of the study. Daily bowel habit diaries were kept throughout the study. The primary outcome measure was differences in the number of complete spontaneous bowel movements (CSBM). Secondary outcome measures were bowel movement frequency and stool form as well as digestive symptoms and comfort. The number of CSBM per week was significantly greater during daily consumption of three kiwifruit compared with the baseline (6·3 v. 3·3; P < 0·05) and the Metamucil® treatment (6·3 v. 4·5; P < 0·05). Stool consistency was also improved, with kiwifruit producing softer stools and less straining (P < 0·05). Gastrointestinal discomfort was also improved compared with baseline for abdominal pain, constipation and indigestion (P < 0·05) during the kiwifruit intervention and constipation during the Metamucil® intervention (P < 0·05). This randomised controlled trial demonstrates that daily consumption of three gold-fleshed kiwifruit is associated with a significant increase of two CSBM per week and reduction in gastrointestinal discomfort in mildly constipated adults.

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

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 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.

Consumption of kiwifruit capsules increases Faecalibacterium prausnitzii abundance in functionally constipated individuals: a randomised controlled human trial.

This study investigated the impact of ACTAZIN™ green (2400 and 600 mg) and Livaux™ (2400 mg) gold kiwifruit supplements on faecal microbial composition and metabolites in healthy and functionally constipated (FC) participants. The participants were recruited into the healthy group (n 20; one of whom did not complete the study) and the FC group (n 9), each of whom consumed all the treatments and a placebo (isomalt) for 4 weeks in a randomised cross-over design interspersed with 2-week washout periods. Modification of faecal microbiota composition and metabolism was determined by 16S rRNA gene sequencing and GC, and colonic pH was calculated using SmartPill® wireless motility capsules. A total of thirty-two taxa were measured at greater than 1 % abundance in at least one sample, ten of which differed significantly between the baseline healthy and FC groups. Specifically, Bacteroidales and Roseburia spp. were significantly more abundant (P < 0·05) in the healthy group and taxa including Ruminococcaceae, Dorea spp. and Akkermansia spp. were significantly more abundant (P < 0·05) in the FC group. In the FC group, Faecalibacterium prausnitzii abundance significantly increased (P = 0·024) from 3·4 to 7·0 % following Livaux™ supplementation, with eight of the nine participants showing a net increase. Lower proportions of F. prausnitzii are often associated with gastrointestinal disorders. The discovery that Livaux™ supplementation increased F. prausnitzii abundance offers a potential strategy for improving gut microbiota composition, as F. prausnitzii is a butyrate producer and has also been shown to exert anti-inflammatory effects in many studies.

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.

Consumption of antimicrobial manuka honey does not significantly perturb the microbiota in the hind gut of mice.

The aim of this study was to test the hypothesis that consuming manuka honey, which contains antimicrobial methylglyoxal, may affect the gut microbiota. We undertook a mouse feeding study to investigate whether dietary manuka honey supplementation altered microbial numbers and their production of organic acid products from carbohydrate fermentation, which are markers of gut microbiota function. The caecum of C57BL/6 mice fed a diet supplemented with antimicrobial UMF® 20+ manuka honey at 2.2 g/kg animal did not show any significantly changed concentrations of microbial short chain fatty acids as measured by gas chromatography, except for increased formate and lowered succinate organic acid concentrations, compared to mice fed a control diet. There was no change in succinate-producing Bacteroidetes numbers, or honey-utilising Bifidobacteria, nor any other microbes measured by real time quantitative PCR. These results suggest that, despite the antimicrobial activity of the original honey, consumption of manuka honey only mildly affects substrate metabolism by the gut microbiota.

Equicarbohydrate partial exchange of kiwifruit for wheaten cereal reduces postprandial glycaemia without decreasing satiety.

Kiwifruit is a carbohydrate food of low glycaemic potency which could potentially be exchanged for starch-based foods in management of postprandial glycaemia. The effect of equicarbohydrate partial exchange of kiwifruit varieties 'Hayward' green (GR) and 'Zesy002' (SunGold; SG) for a starchy wheat-based breakfast cereal (WB) on the characteristics of the postprandial glycaemic response and satiety was therefore determined. A total of twenty non-diabetic subjects (mean age 36 years; mean BMI 24·5 kg/m2) consumed four meals, each containing 40 g available carbohydrate, in random order, after an overnight fast. The meals were: (1) glucose; (2) 70·29 g breakfast cereal; (3) 200 g of GR plus breakfast cereal (30·93 g); and (4) 200 g of SG plus breakfast cereal (27·06 g). Throughout the 180 min postprandial period, capillary blood glucose concentrations were monitored, and satiety rated by a visual analogue scale. Partial kiwifruit substitution of WB significantly reduced postprandial glycaemic response amplitude (glucose, 3·91; WB, 3·66; WB + GR, 2·36; WB + SG, 2·31  mmol/l; least significant difference (LSD) 0·64; P < 0·001) and incremental area under the blood glucose response curve (0-120 min) (glucose, 228; WB, 180; WB + GR, 133; WB + SG, 134 mmol/l × min; LSD 22·7; P < 0·001). The area between baseline and response remained positive in kiwifruit-substituted meals but became negative after 120 min with glucose and WB, indicating that kiwifruit improved homeostatic control. Kiwifruit substitution of cereal did not significantly reduce satiety. We conclude that either 'Hayward' or 'Zesy002' kiwifruit may be used in equicarbohydrate partial substitution of starchy staple foods to reduce glycaemic response and improve glucose homeostasis without decreasing satiety.

The fate of (13)C-labelled and non-labelled inulin predisposed to large bowel fermentation in rats.

The fate of stable-isotope (13)C labelled and non-labelled inulin catabolism by the gut microbiota was assessed in a healthy rat model. Sprague-Dawley male rats were randomly assigned to diets containing either cellulose or inulin, and were fed these diets for 3 days. On day (d) 4, rats allocated to the inulin diet received (13)C-labelled inulin. The rats were then fed the respective non-labelled diets (cellulose or inulin) until sampling (d4, d5, d6, d7, d10 and d11). Post feeding of (13)C-labelled substrate, breath analysis showed that (13)C-inulin cleared from the host within a period of 36 hours. Faecal (13)C demonstrated the clearance of inulin from gut with a (13)C excess reaching maximum at 24 hours (d5) and then declining gradually. There were greater variations in caecal organic acid concentrations from d4 to d6, with higher concentrations of acetic, butyric and propionic acids observed in the rats fed inulin compared to those fed cellulose. Inulin influenced caecal microbial glycosidase activity, increased colon crypt depth, and decreased the faecal output and polysaccharide content compared to the cellulose diet. In summary, the presence of inulin in the diet positively influenced large bowel microbial fermentation.

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.

Polyunsaturated fatty acids modify expression of TGF-ß in a co-culture model ultilising human colorectal cells and human peripheral blood mononuclear cells exposed to Lactobacillus gasseri, Escherichia coli and Staphylococcus aureus.

Commensal bacteria and polyunsaturated fatty acids (PUFAs) have both been shown independently to modulate immune responses. This study tested the hypothesis that the different colonic immunomodulatory responses to commensal (Lactobacillus gasseri) and pathogenic bacteria (Escherichia coli and Staphylococcus aureus) may be modified by PUFAs. Experiments used a Transwell system combining the colorectal cell line HT29, or its mucous secreting sub-clone HT29-MTX, with peripheral blood mononuclear cells to analyse immunomodulatory signalling in response to bacteria, with and without prior treatment with arachidonic acid, eicosapentaenoic acid or docosahexaenoic acid. L. gasseri increased transforming growth factor ß1 (TGF-ß1) mRNA and protein secretion in colonic cell lines when compared with controls, an effect that was enhanced by pre-treatment with eicosapentaenoic acid. In contrast, the Gram-negative pathogen E. coli LF82 had no significant effect on TGF-ß1 protein. L. gasseri also increased IL-8 mRNA but not protein while E. coli increased both; although differences between PUFA treatments were detected, none were significantly different to controls. Colonic epithelial cells show different immunomodulatory signalling patterns in response to the commensal L. gasseri compared to E. coli and S. aureus and pre-treatment of these cells with PUFAs can modify responses. Practical applications: We have demonstrated an interaction between dietary PUFAs and epithelial cell response to both commensal and pathogenic bacteria found in the gastrointestinal tract by utilising in vitro co-culture models. The data suggest that n-3 PUFAs may provide some protection against the potentially damaging effects of pathogens. Furthermore, the beneficial effects of combining n-3 PUFAs and the commensal bacteria, and potential probiotic, L. gasseri are illustrated by the increased expression of immunoregulatory TGF-ß1.

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.

Characterizing kiwifruit carbohydrate utilization in vitro and its consequences for human faecal microbiota.

It is well accepted that our gut bacteria have coevolved with us in relation to our genetics, diet and lifestyle and are integrated metabolically with us to affect our gut health adversely or beneficially. "Who is there" may vary quite widely between individuals, as might "how they do it", but "what they make" may be less variable. Many different individual species of bacteria can perform the same saccharolytic functions and so the availability of substrate (host or diet-derived) along with the degradative enzymes they possess may be key drivers of gut ecology. In this case study, we discuss detailed microbial ecology and metabolism analysis for three individuals following 48 h of in vitro faecal fermentation, using green kiwifruit as the substrate. In parallel, we have analyzed the chemical changes to the kiwifruit carbohydrates present in the fermenta to close the circle on substrate usage/degradative enzymes possessed/microbes present/microbial byproducts produced. In the absence of host carbohydrate, we see that kiwifruit carbohydrates were differentially utilized to drive microbial diversity, yet resulted in similar byproduct production. The starting ecology of each individual influenced the quantitative and qualitative microbial changes; but not necessarily the metabolic byproduct production. Thus, we propose that it is the consistent functional changes that are relevant for assessment of gut health benefits of any food. We recommend that in this era of large scale genotype/-omics studies that hypothesis-driven, bottom-up research is best placed to interpret metagenomic data in parallel with functional, phenotypic data.

Effects of potato fiber and potato-resistant starch on biomarkers of colonic health in rats fed diets containing red meat.

UNLABELLED: The effects of red meat consumption with and without fermentable carbohydrates on indices of large bowel health in rats were examined. Sprague-Dawley rats were fed cellulose, potato fiber, or potato-resistant starch diets containing 12% casein for 2 wk, then similar diets containing 25% cooked beef for 6 wk. After week 8, cecal and colonic microbiota composition, fermentation end-products, colon structure, and colonocyte DNA damage were analyzed. Rats fed potato fiber had lower Bacteroides-Prevotella-Porphyromonas group compared to other diet groups. Colonic Bifidobacterium spp. and/or Lactobacillus spp. were higher in potato fiber and potato-resistant starch diets than in the cellulose diet. Beneficial changes were observed in short-chain fatty acid concentrations (acetic, butyric, and propionic acids) in rats fed potato fiber compared with rats fed cellulose. Phenol and p-cresol concentrations were lower in the cecum and colon of rats fed potato fiber. An increase in goblet cells per crypt and longer crypts were found in the colon of rats fed potato fiber and potato-resistant starch diets. Fermentable carbohydrates had no effect on colonic DNA damage. Dietary combinations of red meat with potato fiber or potato-resistant starch have distinctive effects in the large bowel. Future studies are essential to examine the efficacy of different types of nondigestible carbohydrates in maintaining colonic health during long-term consumption of high-protein diets. PRACTICAL APPLICATION: Improved understanding of interactions between the food consumed and gut microbiota provides knowledge needed to make healthier food choices for large bowel health. The impact of red meat on large bowel health may be ameliorated by consuming with fermentable dietary fiber, a colonic energy source that produces less harmful by-products than the microbial breakdown of colonic protein for energy. Developing functional red meat products with fermentable dietary fiber could be one way to promote a healthy and balanced macronutrient diet.

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.

In vitro utilization of gold and green kiwifruit oligosaccharides by human gut microbial populations.

We examined the effects of whole kiwifruit on gut microbiota using an in vitro batch model of gastric-ileal digestion and colonic fermentation. Faecal fermentations of gold and green kiwifruit, inulin and water (control) digests were performed for up to 48 h. As compared to the control, gold and green kiwifruit increased Bifidobacterium spp. by 0.9 and 0.8 log(10) cfu/ml, respectively (P < 0.001), and the Bacteroides-Prevotella-Porphyromonas group by 0.4 and 0.5 log(10) cfu/ml, respectively. Inulin only had a bifidogenic effect (+0.4 log(10) cfu/ml). This was accompanied with increases in microbial glycosidases, especially those with substrate specificities relating to the breakdown of kiwifruit oligosaccharides, and with increased generation of short chain fatty acids. The microbial metabolic activity was sustained for up to 48 h, which we attribute to the complexity of the carbohydrate substrate provided by whole kiwifruit. Kiwifruit fermenta supernatant was also separately shown to affect the in vitro proliferation of Bifidobacterium longum, and its adhesion to Caco-2 intestinal epithelial cells. Collectively, these data suggest that whole kiwifruit may modulate human gut microbial composition and metabolism to produce metabolites conducive to increased bifidobacteria-host association.