Fecal bacterial activity in symptomatic carbohydrate malabsorption: effect on the fecal short-chain fatty acid ratio

Microbial fermented feed affects flavor amino acids and yolk trimethylamine of duck eggs via cecal microbiota-yolk metabolites crosstalk

Microbial fermented feed (MFF) has been demonstrated to improve nutritional status as well as promote animal health. However, only a few studies have focused on its effect on the flavor of animal products, and the potential underlying mechanisms remain poorly understood. Herein, egg amino acids and yolk trimethylamine (TMA), small intestine histomorphology, cecal microbiota and yolk metabolites were analyzed in MFF-treated ducks. The results showed that MFF significantly increased the flavor amino acids in duck eggs, along with reducing the yolk TMA. MFF caused an increase in beneficial cecal microflora, and regulated the bacteria involved in the metabolism of glucolipid, TMA and its N-oxide. Moreover, MFF regulated 34 annotated metabolites markedly enriched in four metabolic pathways. Correlation analysis showed that cecal microbiota and yolk metabolites were closely related to flavor-related indicators of duck eggs. Our study therefore provides a theoretical basis for improving avian egg flavor starting from the feed.

Fruits and their impact on the gut microbiota, gut motility and constipation

Fruits are the seed-bearing product of plants and have considerable nutritional importance in the human diet. The consumption of fruits is among the dietary strategies recommended for constipation due to its potential effects on the gut microbiota and gut motility. Dietary fiber from fruits has been the subject of research on the impact on gut microbiota, gut motility and constipation, however, fruits also contain other components that impact the intestinal luminal environment that may impact these outcomes including sorbitol and (poly)phenols. This review aims to explore the mechanisms of action and effectiveness of fruits and fruit products on the gut microbiota, gut motility and constipation, with a focus on fiber, sorbitol and (poly)phenols. In vitro, animal and human studies investigating the effects of fruits on gut motility and gut microbiota were sought through electronic database searches, hand searching and consulting with experts. Various fruits have been shown to modify the microbiota in human studies including blueberry powder (lactobacilli, bifidobacteria), prunes (bifidobacteria), kiwi fruit (Bacteroides, Faecalibacterium prausnitzii) and raisins (Ruminococcus, F. prausnitzii). Prunes, raisins and apple fiber isolate have been shown to increase fecal weight in humans, whilst kiwifruit to increase small bowel and fecal water content. Apple fiber isolate, kiwifruit, fig paste, and orange extract have been shown to reduce gut transit time, while prunes have not. There is limited evidence on which fruit components play a predominant role in regulating gut motility and constipation, or whether a synergy of multiple components is responsible for such effects.

Fecal Fermentation in Irritable Bowel Syndrome: Influence of Dietary Restriction of Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols

BACKGROUND/AIMS

Dietary restriction of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) may relieve symptoms in patients with irritable bowel syndrome (IBS). We investigated whether this diet alters microbial fermentation, a process that may be involved in IBS symptom generation.

METHODS

Patients with IBS were included consecutively to participate in a 4-week FODMAP restricted diet. IBS symptoms were evaluated by using the IBS severity scoring system (IBS-SSS). Short-chain fatty acids (SCFAs) were analyzed in fecal samples before and after the dietary intervention, both at baseline and after in vitro fermentation for 24 h.

RESULTS

Sixty-three patients completed the study. Following the dietary intervention, IBS-SSS scores improved significantly (p < 0.0001). Total SCFA levels were reduced in fecal samples analyzed both at baseline (p = 0.005) and after in vitro fermentation for 24 h (p = 0.013). Following diet, baseline levels of acetic (p = 0.003) and n-butyric acids (p = 0.009) decreased, whereas 24 h levels of i-butyric (p = 0.003) and i-valeric acids (p = 0.003) increased. Fecal SCFA levels and IBS symptom scores were not correlated.

CONCLUSION

Dietary FODMAP restriction markedly modulated fecal fermentation in patients with IBS. Saccharolytic fermentation decreased, while proteolytic fermentation increased, apparently independent of symptoms.

Intestinal fermentation in patients with self-reported food hypersensitivity: painful, but protective?

PURPOSE

Enterometabolic disturbances may cause meal-related symptoms. We performed a functional evaluation of the intestinal microflora in patients with unexplained, self-reported food hypersensitivity by measuring fecal short-chain fatty acids (SCFAs).

PATIENTS AND METHODS

Thirty-five consecutive patients with self-reported food hypersensitivity and 15 healthy volunteers of similar age, gender, and body mass index collected all feces for 72 hours. Fecal concentrations of acetic, propionic, n-butyric, i-butyric, n-valeric, i-valeric, n-caproic, and i-caproic acids were analyzed by gas-liquid chromatography. Concentrations and excretions (output) of SCFAs in patients and controls were compared and related to gastrointestinal symptoms.

RESULTS

Despite nonsignificant differences between patients and controls for both total and individual SCFA concentrations and excretions, n-butyric acid comprised a higher (P = 0.035) and acetic acid a lower (P = 0.012) proportion of total SCFA in patients compared to controls. There were no significant correlations between symptom scores and concentrations or excretions of individual or total SCFAs, but the proportion of n-butyric acid was significantly higher in patients with severe symptoms compared to patients with moderate symptoms (P = 0.016).

CONCLUSION

The results indicate an enterometabolic disturbance in patients with self-reported food hypersensitivity. Higher proportions of n-butyric acid may be related to abdominal symptom generation, but may also protect against organic bowel disease. Further studies are needed to clarify these aspects.

Carbohydrate malabsorption in patients with non-specific abdominal complaints

Non-specific abdominal complaints are a considerable problem worldwide. Many patients are affected and many differential diagnoses have to be considered. Among these, carbohydrate malabsorption seems to play an important role. However, so far, only incomplete absorption of lactose is broadly accepted, while the malabsorption of fructose and sorbitol is still underestimated, although in many parts of the world it is much more frequent. Despite the success of dietary interventions in many patients, there are still a lot of unanswered questions that make further investigations necessary.