Curated and harmonized gut microbiome 16S rRNA amplicon data from dietary fiber intervention studies in humans

Next generation amplicon sequencing has created a plethora of data from human microbiomes. The accessibility to this scientific data and its corresponding metadata is important for its reuse, to allow for new discoveries, verification of published results, and serving as path for reproducibility. Dietary fiber consumption has been associated with a variety of health benefits that are thought to be mediated by gut microbiota. To enable direct comparisons of the response of the gut microbiome to fiber, we obtained 16S rRNA sequencing data and its corresponding metadata from 11 fiber intervention studies for a total of 2,368 samples. We provide curated and pre-processed genetic data and common metadata for comparison across the different studies.

Development and Relative Validation of a Food Frequency Questionnaire to Assess Non-Nutritive Sweeteners Intake among Pregnant Women in Santiago, Chile: A Pilot Study

Studies on the effects of non-nutritive sweeteners (NNSs) among pregnant women are scarce and have produced mixed results. One of the major challenges is to accurately assess NNS intake, especially in countries that have implemented policies to prevent obesity and where many foods and beverages have been progressively reformulated to partially or totally replace sugar with NNSs. This study aimed to develop and assess the relative validity of a food frequency questionnaire (FFQ) for use in pregnant women. We developed an FFQ to examine the intake of seven NNSs (acesulfame-k, aspartame, cyclamate, saccharin, sucralose, steviol glycosides, and D-tagatose). This questionnaire was piloted in 29 pregnant women (median age = 31.2 y; 25th-75th percentile: 26.9-34.7) to assess NNS intake over the previous month, compared to 3-day dietary records (3-DR). The validity of this dietary method was assessed using Spearman's correlation coefficient, Lin´s concordance correlation coefficient (CCC), and Bland-Altman plots. Spearman's correlations between the FFQ on NNSs and 3-DR ranged from 0.50 for acesulfame K to 0.83 for saccharin. CCC ranged between 0.22 and 0.66. The Bland-Altman plots showed an overestimation of saccharin, sucralose, and steviol glycosides intake by the FFQ on NNSs compared with 3-DR, and an underestimation of acesulfame K and aspartame. Overall, the NNSs most frequently consumed were sucralose, and none of the participants exceeded the acceptable daily intake for any of the NNSs evaluated. The FFQ on NNSs seems to be reasonably valid in the assessment of NNSs among pregnant women.

Modulation of Postprandial Plasma Concentrations of Digestive Hormones and Gut Microbiota by Foods Containing Oat ß-Glucans in Healthy Volunteers

Cereal β-glucans are beneficial health ingredients that reduce cholesterolemia and postprandial glycaemia. However, their impact on digestive hormones and gut microbiota is not yet fully established. Two randomized, double-blind, controlled studies were conducted. In the first study, 14 subjects ingested a breakfast with or without β-glucan from oats (5.2 g). Compared to the control, β-glucan increased orocecal transit time (p = 0.028) and decreased mean appetite score (p = 0.014) and postprandial plasma ghrelin (p = 0.030), C-peptide (p = 0.001), insulin (p = 0.06), and glucose (p = 0.0006). β-glucan increased plasma GIP (p = 0.035) and PP (p = 0.018) without affecting leptin, GLP-1, PYY, glucagon, amylin, or 7α-hydroxy-4-cholesten-3-one, a biomarker of bile acid synthesis. In the second study, 32 subjects were distributed into 2 groups to ingest daily foods with (3 g/day) or without β-glucan for 3 weeks; stools were collected before/after treatment. No changes in fecal microbiota composition/diversity (deep sequencing) were detected with β-glucans. These results indicate that acute intake of 5 g β-glucan slows transit time and decreases hunger sensation and postprandial glycaemia without affecting bile-acid synthesis, these changes being associated with decreased plasma insulin, C-peptide, and ghrelin, and increased plasma GIP and PP. However, regular daily intake of 3 g β-glucan is not sufficient to have an effect on fecal microbiota composition.

n-3 polyunsaturated fatty acids in the regulation of adipose tissue browning and thermogenesis in obesity: Potential relationship with gut microbiota

BACKGROUND

Obesity is a worldwide public health problem characterized by fat tissue accumulation, favouring adipose tissue and metabolic alterations. Increasing energy expenditure (EE) through brown adipose tissue activation and white adipose tissue (WAT) browning has gained relevance as a therapeutic approach. Different bioactive compounds, such as n-3 polyunsaturated fatty acids (PUFA), have been shown to induce those thermogenic effects. This process is regulated by the gut microbiota as well. Nevertheless, obesity is characterized by gut microbiota dysbiosis, which can be restored by weight loss and n-3 PUFA intake, among other factors. Knowledge gap: However, the role of the gut microbiota on the n-3 PUFA effect in inducing thermogenesis in obesity has not been fully elucidated.

OBJECTIVE

This review aims to elucidate the potential implications of this interrelation on WAT browning adiposw sittue (BAT), BAT activity, and EE regulation in obesity models.

Polyphenols and their anti-obesity role mediated by the gut microbiota: a comprehensive review

Obesity is a global public health problem that results in chronic pathologies such as diabetes, cardiovascular diseases, and cancer. The treatment approach based on energy restriction and promotion of physical activity is ineffective in the long term. Due to the high prevalence of this pathology, complementary treatments such as brown adipose tissue activation (BAT) and white adipose tissue browning (WAT) have been proposed. Dietary polyphenols are plant secondary metabolites that can stimulate browning and thermogenesis of adipose tissue. They have also been shown to prevent body weight gain, and decrease systemic inflammation produced by high-fat diets. Ingested dietary polyphenols that reach the colon are metabolized by the gut microbiota (GM), regulating its composition and generating a great array of metabolites. GM is involved in the production of short chain fatty acids and secondary bile salts that regulate energetic metabolism. The alteration in the composition of GM observed in metabolic diseases such as obesity and type 2 diabetes can be attenuated by polyphenols. Recent studies support the hypothesis that GM would mediate WAT browning and BAT thermogenesis activation induced by polyphenol administration. Together, these results indicate that GM in the presence of polyphenols plays a fundamental role in the control of obesity possible through BAT activation.

The Pros and Cons of Using Algal Polysaccharides as Prebiotics

Macroalgae stand out for their high content of dietary fiber (30–75%) that include soluble, sulfated (fucoidan, agaran, carrageenan, and ulvan) and non-sulfated (laminaran and alginate) polysaccharides. Many studies indicate that these compounds exert varied biological activities and health-promoting effects and for this reason, there is a growing interest for using them in food products. The aim of this review was to critically evaluate prebiotic properties of algal polysaccharides, i.e., their ability to exert biological activities by modulating the composition and/or diversity of gut microbiota (GM). Pre-clinical studies show that the non-sulfated alginate and laminaran are well-fermented by GM, promoting the formation of short chain fatty acids (SCFAs) including butyrate, and preventing that of harmful putrefactive compounds (NH₃, phenol, p-cresol, indole and H₂S). Alginate increases Bacteroides, Bifidobacterium, and Lactobacillus species while laminaran mostly stimulates Bacteroides sp. Results with sulfated polysaccharides are more questionable. Agarans are poorly fermentable but agarose-oligosaccharides exhibit an interesting prebiotic potential, increasing butyrate-producing bacteria and SCFAs. Though carrageenan-oligosaccharides are also fermented, their use is currently limited due to safety concerns. Regarding fucoidan, only one study reports SCFAs production, suggesting that it is poorly fermented. Its effect on GM does not indicate a clear pattern, making difficult to conclude whether it is beneficial or not. Notably, fucoidan impact on H₂S production has not been evaluated, though some studies report it increases sulfate-reducing bacteria. Ulvan is badly fermented by GM and some studies show that part of its sulfate is dissimilated to H₂S, which could affect colonic mitochondrial function. Accordingly, these results support the use of laminaran, alginate and agaro-oligosaccharides as prebiotics while more studies are necessary regarding that of fucoidan, carrageenan and ulvan. However, the realization of clinical trials is necessary to confirm such prebiotic properties in humans.

Overuse of Non-caloric Sweeteners in Foods and Beverages in Chile: A Threat to Consumers' Free Choice?

The prevalence of obesity among Chilean adults and children is one of the highest worldwide. To fight the constant increase of non-communicable diseases and the growing sales of sugar-sweetened beverages, the Chilean government recently enacted a new Law of Food Labeling and Advertising imposing the application of front-of-package warning labels in foodstuffs whose composition exceeds limits for critical nutrients including sugar. Accordingly, food companies have been reformulating their products, incorporating non-caloric sweeteners (NCSs) in partial or total replacement of sucrose. The number of NCS-containing foods and beverages, therefore, has been increasing in the last years. This study aims to identify the NCS-containing products from different food/beverage categories currently available on the Chilean market. Nineteen supermarkets and 13 food web pages were visited by trained dietitians to carry out a systematic search of ingredient information from the different food categories. Overall, 1,489 products were analyzed, of which 815 (55.5%) contained at least one NCS, being this proportion particularly high, compared to other countries. 67.1% of the dairy products, 31.5% of the cereal products, 49% of the processed fruits, 74.3% of the non-alcoholic beverages, and 46.2% of sweets and other desserts contained NCS. Considering the food categories more specifically oriented to children, NCSs were present in 98.8% of powder juices, 98.3% of the flavored milks, 91.2% of jellies, and 79% of the dairy desserts. Sucralose and steviol glycosides were the most widely used NCSs, these sweeteners being present, alone or mixed with other, in 73.5 and 39.7% of the NCS-containing products, respectively, while the use of saccharin and cyclamate was low. In addition, 80 tabletop NCSs were available in the local market, 91.2% of them being sucralose and steviol glycosides (alone or combined). The high number of food products containing steviol glycosides makes very plausible that the daily consumption of this NCS in the pediatric populations could exceed its acceptable daily intake (ADI). The fact that there are no NCS-free foods alternatives for certain food categories, especially for children, is worrying.

The Firmicutes/Bacteroidetes Ratio: A Relevant Marker of Gut Dysbiosis in Obese Patients?

The gut microbiota is emerging as a promising target for the management or prevention of inflammatory and metabolic disorders in humans. Many of the current research efforts are focused on the identification of specific microbial signatures, more particularly for those associated with obesity, type 2 diabetes, and cardiovascular diseases. Some studies have described that the gut microbiota of obese animals and humans exhibits a higher Firmicutes/Bacteroidetes ratio compared with normal-weight individuals, proposing this ratio as an eventual biomarker. Accordingly, the Firmicutes/Bacteroidetes ratio is frequently cited in the scientific literature as a hallmark of obesity. The aim of the present review was to discuss the validity of this potential marker, based on the great amount of contradictory results reported in the literature. Such discrepancies might be explained by the existence of interpretative bias generated by methodological differences in sample processing and DNA sequence analysis, or by the generally poor characterization of the recruited subjects and, more particularly, the lack of consideration of lifestyle-associated factors known to affect microbiota composition and/or diversity. For these reasons, it is currently difficult to associate the Firmicutes/Bacteroidetes ratio with a determined health status and more specifically to consider it as a hallmark of obesity.

Effect of a proanthocyanidin-rich polyphenol extract from avocado on the production of amino acid-derived bacterial metabolites and the microbiota composition in rats fed a high-protein diet

The consumption of high-protein diets (HPDs) increases the flux of undigested proteins moving to the colon. These proteins are hydrolyzed by bacterial proteases and peptidases, releasing amino acids, which in turn are metabolized by the intestinal microbiota (IM) for protein synthesis and production of various metabolites that can exert positive or deleterious effects, depending on their concentrations, at the colonic or systemic level. On the other hand, proanthocyanidins are polymers of flavan-3-ols which cannot be absorbed at the intestinal level, accumulating in the colon where they are fermented by the IM producing metabolites that appear beneficial for colonocytes and also at the peripheral level. This study evaluated the effect of an avocado peel polyphenol extract (AvPPE) rich in proanthocyanidins on the production of cecal bacterial metabolites and microbiota composition in rats fed a HPD. Compared with the normal-protein (NP) group, HPD did not markedly affect the body weight gain of the animals, but increased the kidney weight. Additionally, the HPD induced a higher cecal concentration of ammonia (NH4+/NH3), hydrogen sulfide (H2S) and branched-chain fatty acids (BCFAs). The supplementation with AvPPE attenuated the production of H2S and increased the production of indole. On the other hand, the HPD affected the composition of the cecal microbiota, increasing the relative abundance of the genera Bacteroides and Lactobacillus, while decreasing Prevotella. The AvPPE counteracted the increase induced by the HPD on the genus Lactobacillus, and increased the relative abundance of [Prevotella]. Our results contribute towards explaining the health-promoting effects of proanthocyanidin-rich dietary foodstuffs including fruits and vegetables.

Protective Effect of an Avocado Peel Polyphenolic Extract Rich in Proanthocyanidins on the Alterations of Colonic Homeostasis Induced by a High-Protein Diet

Avocado peel, a byproduct from the avocado pulp industry, is a promising source of polyphenolic compounds. We evaluated the effect of a proanthocyanidin-rich avocado peel polyphenol extract (AvPPE) on the composition and metabolic activity of human fecal microbiota cultured for 24 h in a bioreactor in the presence of high protein (HP) amounts and the effect of the resulting culture supernatants (CSs) on HT-29Glc^-/+ and Caco-2 cells. AvPPE decreased the HP-induced production of ammonia, H₂S, propionate, and isovalerate and increased that of indole and butyrate. Microbiota composition was marginally affected by HP, whileAvPPE increased the microorganisms/abundance of phylum Actinobacteria, families Coriobacteriaceae and Ruminococcaceae, and genus Faecalibacterium. AvPPE failed to prevent the HP-induced decrease of HT-29Glc^-/+ cell viability and energy efficiency but prevented the HP-induced alterations of barrier function in Caco-2 cells. Additionally, the genotoxic effect of the CSs upon HT-29Glc^-/+ was attenuated by AvPPE. Therefore, AvPPE may be considered as a promising product for improving colonic homeostasis.

Quercetin and Epigallocatechin Gallate in the Prevention and Treatment of Obesity: From Molecular to Clinical Studies

Obesity is a worldwide epidemic, which is characterized by the excess accumulation of adipose tissue and to an extent that impairs both the physical and psychosocial health and well-being. There are several weight-loss strategies available, including dietary modification, pharmacotherapy, and bariatric surgery, but many are ineffective or not a long-term solution. Bioactive compounds present in medicinal plants and plant extracts, like polyphenols, constitute the oldest and most extensive form of alternative treatments for the prevention and management of obesity. Their consumption is currently increasing in the population due to the high cost, potential adverse effects, and limited benefits of the currently available pharmaceutical drugs. A great number of studies has explored how dietary polyphenols can interfere with the different mechanisms associated with obesity development. They suggest that these compounds can decrease energy and food intake, lipogenesis, and preadipocyte differentiation and proliferation, while increasing energy expenditure, lipolysis, and fat oxidation. Both quercetin, one of the most common dietary flavonols in the western diet, and epigallocatechin gallate (EGCG), the most abundant polyphenol in green tea, exhibit antiobesity effects in adipocyte cultures and animal models. However, the extrapolation of these potential benefits to obese humans remains unclear. Although quercetin supplementation does not seem to exert any beneficial effects on body weight, this polyphenol could prevent the obesity-associated mortality by reducing cardiovascular disease risk. An important consideration for the design of further trials is the occurrence of gene polymorphisms in key enzymes involved in flavanol metabolism, which determines a subject's sensitivity to catechins and seems, therefore, crucial for the success of the antiobesity intervention. Although the evidence supporting antiobesity effects is more consistent in EGCG than with quercetin studies, they could still be beneficial by reducing the cardiovascular risk of obese subjects, rather than inducing body weight loss.

Acemannan and Fructans from Aloe vera (Aloe barbadensis Miller) Plants as Novel Prebiotics

The nutraceutical properties of Aloe vera have been attributed to a glucomannan known as acemannan. Recently information has been published about the presence of fructans in Aloe vera but there are no publications about acemannan and fructans as prebiotic compounds. This study investigated in vitro the prebiotic properties of these polysaccharides. Our results demonstrated that fructans from Aloe vera induced bacterial growth better than inulin (commercial FOS). Acemannan stimulated bacterial growth less than fructans, and as much as commercial FOS. Using qPCR to study the bacterial population of human feces fermented in a bioreactor simulating colon conditions, we found that fructans induce an increase in the population of Bifidobacterium spp. Fructans produced greater amounts of short chain fatty acids (SCFA), while the branched-chain fatty acids (BCFA) did not increase with these polysaccharides. Acemannan increased significantly acetate concentrations. Therefore, both Aloe vera polysaccharides have prebiotic potentials.

The Gut Microbiota of Healthy Chilean Subjects Reveals a High Abundance of the Phylum Verrucomicrobia

The gut microbiota is currently recognized as an important factor regulating the homeostasis of the gastrointestinal tract and influencing the energetic metabolism of the host as well as its immune and central nervous systems. Determining the gut microbiota composition of healthy subjects is therefore necessary to establish a baseline allowing the detection of microbiota alterations in pathologic conditions. Accordingly, the aim of this study was to characterize the gut microbiota of healthy Chilean subjects using 16S rRNA gene sequencing. Fecal samples were collected from 41 young, asymptomatic, normal weight volunteers (age: 25 ± 4 years; ♀:48.8%; BMI: 22.5 ± 1.6 kg/m²) with low levels of plasma (IL6 and hsCRP) and colonic (fecal calprotectin) inflammatory markers. The V3-V4 region of the 16S rRNA gene of bacterial DNA was amplified and sequenced using MiSeq Illumina system. 109,180 ± 13,148 sequences/sample were obtained, with an α-diversity of 3.86 ± 0.37. The dominant phyla were Firmicutes (43.6 ± 9.2%) and Bacteroidetes (41.6 ± 13.1%), followed by Verrucomicrobia (8.5 ± 10.4%), Proteobacteria (2.8 ± 4.8%), Actinobacteria (1.8 ± 3.9%) and Euryarchaeota (1.4 ± 2.7%). The core microbiota representing the genera present in all the subjects included Bacteroides, Prevotella, Parabacteroides (phylum Bacteroidetes), Phascolarctobacterium, Faecalibacterium, Ruminococcus, Lachnospira, Oscillospira, Blautia, Dorea, Roseburia, Coprococcus, Clostridium, Streptococcus (phylum Firmicutes), Akkermansia (phylum Verrucomicrobia), and Collinsella (phylum Actinobacteria). Butyrate-producing genera including Faecalibacterium, Roseburia, Coprococcus, and Oscillospira were detected. The family Methanobacteriaceae was reported in 83% of the subjects and Desulfovibrio, the most representative sulfate-reducing genus, in 76%. The microbiota of the Chilean individuals significantly differed from those of Papua New Guinea and the Matses ethnic group and was closer to that of the Argentinians and sub-populations from the United States. Interestingly, the microbiota of the Chilean subjects stands out for its richness in Verrucomicrobia; the mucus-degrading bacterium Akkermansia muciniphila is the only identified member of this phylum. This is an important finding considering that this microorganism has been recently proposed as a hallmark of healthy gut due to its anti-inflammatory and immunostimulant properties and its ability to improve gut barrier function, insulin sensitivity and endotoxinemia. These results constitute an important baseline that will facilitate the characterization of dysbiosis in the main diseases affecting the Chilean population.

The Gastrointestinal Tract as a Key Target Organ for the Health-Promoting Effects of Dietary Proanthocyanidins

Proanthocyanidins (PACs) are polymers of flavan-3-ols abundant in many vegetable foods and beverages widely consumed in the human diet. There is increasing evidence supporting the beneficial impact of dietary PACs in the prevention and nutritional management of non-communicable chronic diseases. It is considered that PACs with a degree of polymerization >3 remain unabsorbed in the gastrointestinal (GI) tract and accumulate in the colonic lumen. Accordingly, the GI tract may be considered as a key organ for the healthy-promoting effects of dietary PACs. PACs form non-specific complexes with salivary proteins in mouth, originating the sensation of astringency, and with dietary proteins, pancreatic enzymes, and nutrient transporters in the intestinal lumen, decreasing the digestion and absorption of carbohydrates, proteins, and lipids. They also exert antimicrobial activities, interfering with cariogenic or ulcerogenic pathogens in the mouth (Streptococcus mutans) and stomach (Helicobacter pylori), respectively. Through their antioxidant and antiinflammatory properties, PACs decrease inflammatory processes in animal model of gastric and colonic inflammation. Interestingly, they exert prebiotic activities, stimulating the growth of Lactobacillus spp. and Bifidobacterium spp. as well as some butyrate-producing bacteria in the colon. Finally, PACs are also metabolized by the gut microbiota, producing metabolites, mainly aromatic acids and valerolactones, which accumulate in the colon and/or are absorbed into the bloodstream. Accordingly, these compounds could display biological activities on the colonic epithelium or in extra-intestinal tissues and, therefore, contribute to part of the beneficial effects of dietary PACs.

The Elevated Rate of Cesarean Section and Its Contribution to Non-Communicable Chronic Diseases in Latin America: The Growing Involvement of the Microbiota

The current recommendation of the World Health Organization (WHO) regarding cesarean section (C-section) is that this clinical practice should be carried out only under specific conditions, when the health or life of the mother/newborn dyad is threatened, and that its use should not exceed 10-15% of the total deliveries. However, over the last few decades, the frequency of C-section delivery in medium- and high-income countries has rapidly increased worldwide. This review describes the evolution of this procedure in Latin American countries, showing that today more than half of newborns in the region are delivered by C-section. Given that C-section delivery is more expensive than vaginal delivery, its use has increased more rapidly in the private than the public sector; nevertheless, the prevalence of C-section deliveries in the public sector is higher than the WHO's recommendations and continues to increase, representing a growing challenge for Latin America. Although the medium- and long-term consequences of C-section delivery, as opposed to vaginal delivery, on the infant health are unclear, epidemiological studies suggest that it is associated with higher risk of developing asthma, food allergy, type 1 diabetes, and obesity during infancy. These findings are important, as the incidence of these diseases in the Latin American pediatric population is also increasing, particularly obesity. Although the link between these diseases and delivery mode remains controversial, recent studies indicate that the establishment of the gut microbiota is delayed in infants born by C-section during the postnatal period, i.e., during a critical developmental window for the maturation of the newborn's immune system. This delay may favor the subsequent development of inflammatory and metabolic disorders during infancy. Accordingly, from a public health perspective, it is important to slow down and eventually reverse the pattern of increased C-section use in the affected populations.

Deleterious Effect of p-Cresol on Human Colonic Epithelial Cells Prevented by Proanthocyanidin-Containing Polyphenol Extracts from Fruits and Proanthocyanidin Bacterial Metabolites

The protective effect of proanthocyanidin-containing polyphenol extracts from apples, avocados, cranberries, grapes, or proanthocyanidin microbial metabolites was evaluated in colonic epithelial cells exposed to p-cresol, a deleterious compound produced by the colonic microbiota from l-tyrosine. In HT29 Glc(-/+) cells, p-cresol significantly increased LDH leakage and decreased ATP contents, whereas in Caco-2 cell monolayers, it significantly decreased the transepithelial electrical resistance and increased the paracellular transport of FITC-dextran. The alterations induced by p-cresol in HT29 Glc(-/+) cells were prevented by the extracts from cranberries and avocados, whereas they became worse by extracts from apples and grapes. The proanthocyanidin bacterial metabolites decreased LDH leakage, ameliorating cell viability without improving intracellular ATP. All of the polyphenol extracts and proanthocyanidin bacterial metabolites prevented the p-cresol-induced alterations of barrier function. These results suggest that proanthocyanidin-containing polyphenol extracts and proanthocyanidin metabolites likely contribute to the protection of the colonic mucosa against the deleterious effects of p-cresol.

What goes around comes around: novel pharmacological targets in the gut-brain axis

The gut and the brain communicate bidirectionally through anatomic and humoral pathways, establishing what is known as the gut-brain axis. Therefore, interventions affecting one system will impact on the other, giving the opportunity to investigate and develop future therapeutic strategies that target both systems. Alterations in the gut-brain axis may arise as a consequence of changes in microbiota composition (dysbiosis), modifications in intestinal barrier function, impairment of enteric nervous system, unbalanced local immune response and exaggerated responses to stress, to mention a few. In this review we analyze and discuss several novel pharmacological targets within the gut-brain axis, with potential applications to improve intestinal and mental health.

Impact of Dietary Lipids on Colonic Function and Microbiota: An Experimental Approach Involving Orlistat-Induced Fat Malabsorption in Human Volunteers

OBJECTIVES:

High-fat diets alter gut microbiota and barrier function, inducing metabolic endotoxemia and low-grade inflammation. Whether these effects are due to the high dietary lipid content or to the concomitant decrease of carbohydrate intake is unclear. The aim of this study was to determine whether higher amounts of dietary fat reaching the colon (through orlistat administration) affect the colonic ecosystem in healthy volunteers and the effect of the prebiotic oligofructose (OF) in this model.

METHODS:

Forty-one healthy young subjects were distributed among four groups: Control (C), Prebiotic (P), Orlistat (O), and Orlistat/Prebiotic (OP). They consumed a fat-standardized diet (60 g/day) during Week-1 (baseline) and after 1 week of washout, Week-3. During Week-3, they also received their respective treatment (Orlistat: 2 × 120 mg/day, OF: 16 g/day, and maltodextrin as placebo). A 72-h stool collection was carried out at the end of Week-1 (T0) and Week-3 (T1). Fecal fat, calprotectin, and short-chain fatty acids (SCFAs) as well as the antioxidant activity of fecal waters (ferric-reducing antioxidant power), fecal microbiota composition (by deep sequencing), and gut permeability (Sucralose/Lactulose/Mannitol test) were determined at these times.

RESULTS:

Fecal fat excretion was higher in the O (P=0.0050) and OP (P=0.0069) groups. This event was accompanied, in the O group, by an increased calprotectin content (P=0.047) and a decreased fecal antioxidant activity (P=0.047). However, these alterations did not alter gut barrier function and the changes observed in the composition of the fecal microbiota only affected bacterial populations with low relative abundance (<0.01%); in consequences, fecal SCFA remained mainly unchanged. Part of the colonic alterations induced by orlistat were prevented by OF administration.

CONCLUSIONS:

In the context of an equilibrated diet, the acute exposition of the colonic ecosystem to high amounts of dietary lipids is associated with an incremented excretion of fecal calprotectin and pro-oxidant activity of the colonic content, in the absence of significant changes in the microbiota.

Spray Freeze-Drying as an Alternative to the Ionic Gelation Method to Produce Chitosan and Alginate Nano-Particles Targeted to the Colon

Chitosan and alginate nano-composite (NP) carriers intended for colonic delivery containing prednisolone and inulin were obtained by two processes. Spray freeze-drying using chitosan (SFDC) or alginate (SFDA) was proposed as an alternative to the traditional chitosan-tripolyphosphate platform (CTPP). NPs were fully characterised and assessed for their yield of particles; level of prednisolone and inulin release in phosphate and Krebs buffers; and sensitivity to degradation by lysozyme, bacteria and faecal slurry. NPs based on chitosan showed similar properties (size, structure, viscoelastic behaviour), but those based on SFDC showed a higher mean release of both active ingredients, with similar efficiency of encapsulation and loading capacity for prednisolone but lower for inulin. SFDC was less degraded in the presence of lysozyme and E. coli and was degraded by B. thetaiotaomicron but not by faecal slurry. The results obtained with SFDA were promising because this NP showed good encapsulation parameters for both active ingredients and biological degradability by E. coli and faecal slurry. However, it will be necessary to use alginate derivatives to reduce its solubility and improve its mechanical behaviour.

The deleterious metabolic and genotoxic effects of the bacterial metabolite p-cresol on colonic epithelial cells

p-Cresol that is produced by the intestinal microbiota from the amino acid tyrosine is found at millimolar concentrations in the human feces. The effects of this metabolite on colonic epithelial cells were tested in this study. Using the human colonic epithelial HT-29 Glc(-/+) cell line, we found that 0.8mM p-cresol inhibits cell proliferation, an effect concomitant with an accumulation of the cells in the S phase and with a slight increase of cell detachment without necrotic effect. At this concentration, p-cresol inhibited oxygen consumption in HT-29 Glc(-/+) cells. In rat normal colonocytes, p-cresol also inhibited respiration. Pretreatment of HT-29 Glc(-/+) cells with 0.8mM p-cresol for 1 day resulted in an increase of the state 3 oxygen consumption and of the cell maximal respiratory capacity with concomitant increased anion superoxide production. At higher concentrations (1.6 and 3.2mM), p-cresol showed similar effects but additionally increased after 1 day the proton leak through the inner mitochondrial membrane, decreasing the mitochondrial bioenergetic activity. At these concentrations, p-cresol was found to be genotoxic toward HT-29 Glc(-/+) and also LS-174T intestinal cells. Lastly, a decreased ATP intracellular content was observed after 3 days treatment. p-Cresol at 0.8mM concentration inhibits colonocyte respiration and proliferation. In response, cells can mobilize their "respiratory reserve." At higher concentrations, p-cresol pretreatment uncouples cell respiration and ATP synthesis, increases DNA damage, and finally decreases the ATP cell content. Thus, we have identified p-cresol as a metabolic troublemaker and as a genotoxic agent toward colonocytes.

The intake of maqui (Aristotelia chilensis) berry extract normalizes H2O2 and IL-6 concentrations in exhaled breath condensate from healthy smokers - an explorative study

BACKGROUND

Respiratory diseases are associated with pulmonary oxidative stress and inflammatory processes. Though studies in animal models suggest that dietary polyphenols improve lung injury, no intervention studies were carried out in humans. The aim of this study was to determine whether the intake of an anthocyanin-rich maqui extract improved H2O2 and IL-6 concentrations in exhaled breath condensates (EBCs) from asymptomatic smokers.

FINDINGS

15 asymptomatic smokers with mild cigarette smoking (3 pack-year [2.4 - 7.7]) (mean [CI95%]) were recruited in this exploratory longitudinal study. They ingested 2 g of maqui extract (polyphenol content = 5.18 ± 2.00 g GAE/100 g; FRAP value = 27.1 ± 2.0 mmol Fe(++)/100 g), twice daily for two weeks. EBCs were collected before and after treatment and the changes in H2O2 and IL-6 concentrations were determined by fluorimetry and Elisa, respectively. The EBC contents of H2O2 and IL-6 H2O2 before and after treatment in smokers were also compared with those determined in single EBC samples from 8 healthy non-smokers subjects. At baseline, the H2O2 concentrations were higher and those of IL-6 lower in the smokers than in the non-smokers. Maqui extract significantly decreased H2O2 (p < 0.0002) and increased IL-6 (p < 0.004) in the EBC from smokers. The EBC concentrations of H2O2 and IL-6 after maqui administration did not differ between smokers and non-smokers.

CONCLUSIONS

Maqui extract normalizes IL-6 and H2O2 concentrations in EBC from humans with mild smoking habits. If confirmed, these results suggest that dietary polyphenols might be considered as an interesting alternative for the dietary management of respiratory disorders.

Review article: intestinal barrier dysfunction and central nervous system disorders--a controversial association

BACKGROUND

Central nervous system (CNS) development and physiopathology are greatly affected by environmental stimuli. The intestinal barrier restricts the entrance of toxins, pathogens, and antigens while modulating the expression of various neuroactive compounds. The existence of a rich gut-to-brain communication raises the possibility that intestinal barrier alterations may take part in the pathophysiology of CNS disorders.

AIM

To review evidence associating intestinal barrier dysfunction with the development of CNS disorders.

METHODS

Literature search was conducted on PubMed using the following terms: intestinal barrier, intestinal permeability, central nervous system, mental disorders, schizophrenia, autism, stress, anxiety, depression, and neurodegeneration.

RESULTS

Clinical and animal model studies of the association between intestinal barrier and schizophrenia, autism spectrum disorders, neurodegenerative diseases or depression were reviewed. The majority of reports concentrated on schizophrenia and autism spectrum disorders. About half of these described increased intestinal permeability/mucosal damage in patients compared with healthy controls, with up to 43% of children with autism spectrum disorders and up to 35% of schizophrenia patients displaying abnormally high urinary excretion of the sugars used as permeability markers. However, another substantial group of studies did not find such differences. In autism spectrum disorders, some reports show that the use of diets such as the gluten-free casein-free diet may contribute to the normalisation of lactulose/mannitol ratio, but to date there is no adequately controlled study showing improvement in behavioural symptoms following these dietary interventions.

CONCLUSIONS

Evidence of altered intestinal permeability in individuals suffering from CNS disorders is limited and cannot be regarded as proven. Moreover the efficacy of targeting gut barrier in the management of neurological and behavioural aspects of CNS disorders has not yet been established, and needs further investigation.

Probiotic screening and safety evaluation of Lactobacillus strains from plants, artisanal goat cheese, human stools, and breast milk

The aim of this study was to select autochthonous strains of Lactobacillus from stools of healthy infants and adults, human milk, artisanal goat cheese, and fruits and vegetables according to their probiotic properties and safety. From 421 strains of Lactobacillus isolated, 102 (24.2%) were shown to be tolerant to gastric pH and bile salts; they were used to determine their anti-Helicobacter pylori (agar diffusion assay), antioxidant (oxygen radical absorption capacity), and anti-inflammatory (inhibition of interleukin-8 release by tumor necrosis factor-α-stimulated HT-29 cells) activities as well as their ability to adhere to intestinal (Caco-2) and gastric (AGS) epithelial cells. Results obtained were compared with three commercial probiotic Lactobacillus rhamnosus GG, L. plantarum 299v, and L. johnsonii NCC533. The five strains most efficient according to these activities were subsequently identified by sequencing their 16S rRNA gene, their susceptibility to antibiotics was determined, and their safety evaluated in mice. One strain of L. plantarum was discarded due to the higher prevalence of liver bacterial translocation observed in the animals fed this strain. In conclusion, four autochthonous strains of L. rhamnosus were finally selected with probiotic properties and safety allowing their eventual use in human studies. These results contribute to increase the diversity of probiotic strains available for the development of nutraceuticals and functional foods.

Release of prednisolone and inulin from a new calcium-alginate chitosan-coated matrix system for colonic delivery

Putative colonic release formulations of calcium (Ca)-alginate coated with chitosan containing two different actives, prednisolone and inulin, were prepared in three different sizes, beads (D50 = 2104 μm) and microparticles (D50 = 354 and 136 μm). The formulations were tested in standard phosphate buffer and biorelevant Krebs bicarbonate buffer at pH 7.4, and were further evaluated in the presence of the bacterium E. coli. Product yield and encapsulation were higher with prednisolone than with inulin. In Krebs bicarbonate buffer, a clear relationship between particle size and prednisolone release was observed. In contrast, release of inulin was independent of the particle size. In phosphate buffer, the particles eroded quickly, whereas in Krebs buffer, the particles swelled slowly. The difference in behavior can be attributed to the formation of calcium phosphate in the phosphate buffer medium, which in turn weakens the Ca-alginate matrix core. In the presence of E. coli, the formulations were fermented and the release of prednisolone was accelerated. In conclusion, the buffer media affects formulation behavior and drug release, with the bicarbonate media providing a better simulation of in vivo behavior. Moreover, the susceptibility of the formulations to bacterial action indicates their suitability as carriers for colonic drug delivery.

Polyphenols protect the epithelial barrier function of Caco-2 cells exposed to indomethacin through the modulation of occludin and zonula occludens-1 expression

The aim of this study was to determine the protective effect of quercetin, epigallocatechingallate, resveratrol, and rutin against the disruption of epithelial integrity induced by indomethacin in Caco-2 cell monolayers. Indomethacin decreased the transepithelial electrical resistance and increased the permeability of the monolayers to fluorescein-dextran. These alterations were abolished by all the tested polyphenols but rutin, with quercetin being the most efficient. The protective effect of quercetin was associated with its capacity to inhibit the redistribution of ZO-1 protein induced in the tight junction by indomethacin or rotenone, a mitochondrial complex-I inhibitor, and to prevent the decrease of ZO-1 and occludin expression induced by indomethacin. The fact that the antioxidant polyphenols assayed in this study differ in their protective capacity against the epithelial damage induced by indomethacin suggests that this damage is due to the ability of this agent to induce not only oxidative stress but also mitochondrial dysfunction.

Re-print of "Intestinal luminal nitrogen metabolism: role of the gut microbiota and consequences for the host"

Alimentary and endogenous proteins are mixed in the small intestinal lumen with the microbiota. Although experimental evidences suggest that the intestinal microbiota is able to incorporate and degrade some of the available amino acids, it appears that the microbiota is also able to synthesize amino acids raising the view that amino acid exchange between the microbiota and host can proceed in both directions. Although the net result of such exchanges remains to be determined, it is likely that a significant part of the amino acids recovered from the alimentary proteins are used by the microbiota. In the large intestine, where the density of bacteria is much higher than in the small intestine and the transit time much longer, the residual undigested luminal proteins and peptides can be degraded in amino acids by the microbiota. These amino acids cannot be absorbed to a significant extent by the colonic epithelium, but are precursors for the synthesis of numerous metabolic end products in reactions made by the microbiota. Among these products, some like short-chain fatty acids and organic acids are energy substrates for the colonic mucosa and several peripheral tissues while others like sulfide and ammonia can affect the energy metabolism of colonic epithelial cells. More work is needed to clarify the overall effects of the intestinal microbiota on nitrogenous compound metabolism and consequences on gut and more generally host health.

Differential protective effects of quercetin, resveratrol, rutin and epigallocatechin gallate against mitochondrial dysfunction induced by indomethacin in Caco-2 cells

The beneficial effects of dietary polyphenols on health are due not only to their antioxidant properties but also to their antibacterial, anti-inflammatory and/or anti-tumoral activities. It has recently been proposed that protection of mitochondrial function (which is altered in several diseases such as Alzheimer, Parkinson, obesity and diabetes) by these compounds, may be important in explaining the beneficial effects of polyphenols on health. The aim of this study was to evaluate the protective effects of dietary polyphenols quercetin, rutin, resveratrol and epigallocatechin gallate against the alterations of mitochondrial function induced by indomethacin (INDO) in intestinal epithelial Caco-2 cells, and to address the mechanism involved in such damaging effect by INDO, which generates oxidative stress. INDO concentration dependently decreases cellular ATP levels and mitochondrial membrane potential in Caco-2 cells after 20min of incubation. INDO also inhibits the activity of mitochondrial complex I and causes accumulation of NADH; leading to overproduction of mitochondrial O(2)()(-), since it is prevented by pyruvate. Quercetin (0.01mg/ml), resveratrol (0.1mg/ml) and rutin (1mg/ml) protected Caco-2 cells against INDO-induced mitochondrial dysfunction, while no protection was observed with epigallocatechin gallate. Quercetin was the most efficient in protecting against mitochondrial dysfunction; this could be due to its ability to enter cells and accumulate in mitochondria. Additionally its structural similarity with rotenone could favor its binding to the ubiquinone site of complex I, protecting it from inhibitors such as INDO or rotenone. These findings suggest a possible new protective role for dietary polyphenols for mitochondria, complementary of their antioxidant property. This new role might expand the preventive and/or therapeutic use of PPs in conditions involving mitochondrial dysfunction and associated with increased oxidative stress at the cellular or tissue levels.

Apple peel polyphenol extract protects against indomethacin-induced damage in Caco-2 cells by preventing mitochondrial complex I inhibition

The aim of this work was to investigate the role of mitochondrial dysfunction in the development of oxidative stress and cytotoxicity induced by indomethacin and to evaluate the potential of an apple peel polyphenol extract (APPE) in protecting against these events. Indomethacin induced, time-dependently, mitochondrial and oxidative perturbations which led to cell losses. An inhibition of complex I activity, shown for first time here, which resulted in a concomitant drop in cellular ATP and an increment in mitochondrial superoxide production, was observed after 10 min of exposure. These early cytotoxicity-triggering events were followed by an increase in the intracellular production of superoxide (20 min), an elevation in the activity of xanthine oxidase which led to an increased lipid peroxidation (30 min), and a decline in cell viability which manifested after 40 min. These events were selectively prevented using allopurinol, tempol and APPE (a standardized apple peel polyphenol extract). While the oxidative and cell lytic effects of indomethacin were equally prevented by the three agents, only APPE protected against complex I inhibition and its downstream oxidative consequences. Since tempol (a SOD mimetic) prevented the elevation in xanthine oxidase activity, and allopurinol (a xanthine oxidase inhibitor) totally abolished the increment in lipid peroxidation and loss of cell viability, it appears that a superoxide-dependent increase in xanthine oxidase activity is critical to trigger cytotoxicity. Thus, preventing the early increment in superoxide formation that, as a result of inhibiting complex I, takes place within mitochondria would be key toward protecting the cells against the oxidative and cytolytic effects of indomethacin. The ability of APPE in preventing the inhibition of complex I and the subsequent superoxide-dependent increase in XO activity warrants further studies to evaluate the mechanism involves in the protecting effect of APPE against the indomethacin-associated adverse effects in vivo.

Apple peel polyphenols protect against gastrointestinal mucosa alterations induced by indomethacin in rats

The stability of an apple peel polyphenol extract (APPE) with powerful antioxidant activity was evaluated under acidic conditions in vitro, and its protective effect against gastrointestinal damage was investigated in rats treated with indomethacin. The antioxidant activity of APPE remained stable at pH 2.0 for 4 h. In rats treated with indomethacin (40 mg/kg ig), the previous administration of APPE protected the gastric, intestinal, and colonic mucosa from oxidative stress by preventing increased malondialdehyde concentrations and decreasing the GSH/GSSG ratio. APPE also displayed anti-inflammatory effects by preventing neutrophil infiltration in the mucosa, as evidenced by the lower myeloperoxidase activity. These protective effects of APPE resulted in the prevention of macro- and microscopic damage and of barrier dysfunction along the gastrointestinal tract of the indomethacin-treated animals. This study supports the concept that apple peel polyphenols may be useful in the prevention and/or treatment of nonsteroidal anti-inflammatory drug-associated side effects.

Increase of plasma fatty acids without changes in n-6/n-3-PUFA ratio in asymptomatic obese subjects

Obesity is associated with a low grade inflammation which contributes to the development of insulin resistance and diabetes. The aim of this study was to assess the total saturated (SFAs), monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) in plasma from asymptomatic obese subjects and to determine the arachidonic/eicosapentanoic acid ratio [ARA/EPA] as a marker of inflammation, and its eventual association with ultrasensitive CRP. Fourteen obese (34.4 +/- 11.1y.; BMI: 36.0 +/- 4,5 kg/m2) and 12 normal-weight (30.6 +/- 7.8y.; BMI: 23,6 +/- 2,4 kg/m2) subjects were recruited and their plasma fatty acids were determined by gas chromatography. usCRP was higher in the obese subjects (p = 0.01) and correlates with their body fat content. The percentages of SFAs, MUFAs, PUFAs were not affected in the obese subjects but their concentrations were increased, compared with the control group. However, no differences in the long chain PUFAs (DHA and EPA) concentrations or in the plasmatic ARA/EPA ratio were observed in these subjects. These observations do not support a relation between the ARA/EPA ratio and the presence of low grade inflammation evaluated by plasma usCRP in this group of asymptomatic obese subjects.

Identification of Lactobacillus spp. in colostrum from Chilean mothers

The biodiversity of Lactobacillus spp. in colostrum samples from 116 Chilean mothers was analyzed by PCR and 16S rDNA sequencing. Lactobacilli were isolated in 55.3% of the samples, with concentrations of 3.33 +/- 0.55 (log CFU/ml). The predominant species were L. plantarum (64%), L. fermentum (16%) and L. pentosus (9%). 28% of the isolated strains were resistant to gastric pH and bile salts, suggesting that they could be used as probiotics.

Protection by apple peel polyphenols against indometacin-induced oxidative stress, mitochondrial damage and cytotoxicity in Caco-2 cells

OBJECTIVES

Exposure of Caco-2 cells to indometacin can be a useful model to assess some of the cytotoxic events that appear to underlie the gastrointestinal lesions associated with the use of this anti-inflammatory agent. Using such a cellular model, we addressed here the cytoprotective potential of a recently standardized apple peel polyphenol extract, APPE.

METHODS

We firstly characterized APPE in terms of its free radical scavenging and antioxidant properties, and subsequently investigated its potential to protect Caco-2 cells against the deleterious effects of indometacin on cellular oxidative status (redox state, malondialdehyde, glutathione (GSH) and oxidized glutathione (GSSG) levels), mitochondrial function (ATP and mitochondrial membrane potential) and cell viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and lactate dehydrogenase (LDH) leakage). For comparative purposes, the free radical scavenging properties and reducing capacity of quercetin, epicatechin and rutin were also estimated.

KEY FINDINGS

In the absence of APPE, indometacin induced mitochondrial perturbations (reducing ATP and the mitochondrial membrane potential), enhanced the oxidative status (decreasing the GSH/GSSG ratio and increasing dichlorofluorescein oxidation and malondialdehyde) and lowered the cell viability (decreasing MTT reduction and increasing LDH leakage). APPE, whether pre-added or co-incubated with indometacin, concentration-dependently prevented these mitochondrial, oxidative and cell viability alterations. Prompted by the recently recognized ability of indometacin to enhance the mitochondrial formation of reactive oxygen species, APPE was also characterized in terms of its free radical-scavenging capacity. APPE was found to actively scavenge O(2).(-), HO. and peroxyl radicals. Such free radical-scavenging activity of APPE suggests that its ability to protect mitochondria and prevent the oxidative and lytic damage induced by indometacin arises from its potent antioxidant capacity.

CONCLUSIONS

In Caco-2 cells APPE prevented mitochondrial oxidative and cell viability alterations induced by indometacin possibly through its ability to scavenge reactive oxygen species. These findings are of interest in view of the high prevalence of gastrointestinal side-effects associated with the use of conventional anti-inflammatory agents.

Pilot study: alterations of intestinal microbiota in obese humans are not associated with colonic inflammation or disturbances of barrier function

BACKGROUND

Obesity is associated with low-grade inflammation contributing to insulin-resistance. Gut barrier alterations, described in animal models of obesity, probably favour inflammation. This has not been hitherto described in obese humans.

AIM

To evaluate gut permeability in asymptomatic obese and its association with plasma (C-reactive protein (CRP), arachidonate/eicosapentaenoate ratio) and faecal (calprotectin and leptin) markers of inflammation and microbiota alterations.

METHODS

A total of 13 obese (age: 33.9 ± 11.5 years; BMI: 35.9 ± 5.0 kg/m²) and 11 control subjects (age: 30.3 ± 8.1 years; BMI: 23.5 ± 2.4 kg/m²) were recruited. Gut permeability was assessed by the lactulose-mannitol-sucralose test, plasma fatty acids by gas chromatography, faecal calprotectin and leptin by Elisa and faecal microbiota by G+C profiling.

RESULTS

C-reactive protein was increased in the obese subjects (P = 0.01), but neither the plasma arachidonate/eicosapentaenoate ratio, the faecal levels of calprotectin and leptin, nor the gut permeability were altered. The faecal microbiota was altered in the obese (P = 0.0002), with predominance of bacterial populations having a lower G+C content and decreased concentrations of high G+C populations.

CONCLUSIONS

Asymptomatic obese individuals with systemic low-grade inflammation do not have evidence of colonic inflammation or gut barrier alteration; however, the biodiversity of their intestinal microbiota is affected.

Urinary D-lactate excretion in infants receiving Lactobacillus johnsonii with formula

BACKGROUND/AIMS

Supplementation with certain probiotics can improve gut microbial flora and immune function but should not have adverse effects. This study aimed to assess the risk of D-lactate accumulation and subsequent metabolic acidosis in infants fed on formula containing Lactobacillus johnsonii (La1).

METHODS

In the framework of a double-blind, randomized controlled trial enrolling 71 infants aged 4-5 months, morning urine samples were collected before and 4 weeks after being fed formulas with or without La1 (1 x 10(8)/g powder) or being breastfed. Urinary D- and L-lactate concentrations were assayed by enzymatic, fluorimetric methods and excretion was normalized per mol creatinine.

RESULTS

At baseline, no significant differences in urinary D-/L-lactate excretion among the formula-fed and breastfed groups were found. After 4 weeks, D-lactate excretion did not differ between the two formula groups, but was higher in both formula groups than in breastfed infants. In all infants receiving La1, urinary D-lactate concentrations remained within the concentration ranges of age-matched healthy infants which had been determined in an earlier study using the same analytical method. Urinary L-lactate also did not vary over time or among groups.

CONCLUSIONS

Supplementation of La1 to formula did not affect urinary lactate excretion and there is no evidence of an increased risk of lactic acidosis.

Modulation of Helicobacter pylori colonization with cranberry juice and Lactobacillus johnsonii La1 in children

OBJECTIVE

Probiotics and cranberry have been shown to inhibit Helicobacter pylori in vitro owing to bacteriocin production and high levels of proanthocyanidins, respectively. These effects have been confirmed in clinical trials with H. pylori-positive subjects. The aim of this study was to evaluate whether regular intake of cranberry juice and the probiotic Lactobacillus johnsonii La1 (La1) may result in an additive or synergistic inhibition of H. pylori in colonized children.

METHODS

A multicentric, randomized, controlled, double-blind trial was carried out in 295 asymptomatic children (6-16 y of age) who tested positive for H. pylori by (13)C-urea breath test (UBT). Subjects were allocated in four groups: cranberry juice/La1 (CB/La1), placebo juice/La1 (La1), cranberry juice/heat-killed La1 (CB), and placebo juice/heat-killed La1 (control). Cranberry juice (200 mL) and La1 product (80 mL) were given daily for 3 wk, after which a second UBT was carried out. A third UBT was done after a 1-mo washout in those children who tested negative in the second UBT.

RESULTS

Two hundred seventy-one children completed the treatment period (dropout 8.1%). Helicobacter pylori eradication rates significantly differed in the four groups: 1.5% in the control group compared with 14.9%, 16.9%, and 22.9% in the La1, CB, and CB/La1 groups, respectively (P < 0.01); the latter group showed a slight but not significant increase when compared with the other treated groups. The third UBT was carried out only in 19 of the 38 children who tested negative in the second UBT and H. pylori was detected in 80% of them.

CONCLUSION

These results suggest that regular intake of cranberry juice or La1 may be useful in the management of asymptomatic children colonized by H. pylori; however, no synergistic inhibitory effects on H. pylori colonization were observed when both foodstuffs were simultaneously consumed.

Effect of a lactose-free milk formula supplemented with bifidobacteria and streptococci on the recovery from acute diarrhoea

Probiotics have been proposed for the management and prevention of acute diarrhoea in infants. A double-blind, randomised, placebo controlled study was carried out in 224 Chinese infants 6 to 36 months of age with severe acute diarrhoea and free from moderate or severe malnutrition. After oral or parenteral rehydration, they were allocated to one of three groups: a lactose-free formula (Control); the same formula but with viable 10(8)CFU B. lactis Bb12 and 5x10(7)CFU St. thermophilus TH4 per gram of powder and, the same formula with the same microorganisms, but with 10(9)CFU/g and 5x10(8)CFU, respectively. Anthropometric parameters, duration of the diarrhoea and rotavirus shedding were evaluated. Eighty seven percent of the episodes were associated with rotavirus infection. The duration of the diarrhoea was not influenced by the intake of probiotics. However, a decrease of rotavirus shedding was observed in infants fed the formula with 10(9) Bb12/g, a finding of probable epidemiological importance in the transmission of this agent.

Coerulear activation by crh and its role in hypertension induced by prenatal malnutrition in the rat

The effects of intracoerulear CRH and intraparaventricular prazosin on systolic pressure, diastolic pressure and heart rate were studied in prenatally malnourished hypertensive rats. At day 40 of life, (i) malnourished rats showed enhanced systolic pressure, heart rate, and plasma corticosterone; (ii) intracoerulear CRH increased systolic pressure and heart rate only in controls; (iii) intraparaventricular prazosin decreased systolic pressure and heart rate only in malnourished rats; (iv) in controls, prazosin did not prevent the stimulatory effect of CRH on the cardiovascular parameters; in malnourished rats, prazosin allowed CRH regain its stimulatory effects. Thus, coerulear activation by CRH would be involved in hypertension and tachycardia developed by prenatally malnourished animals.

Functional fermented milk products

Fermented foods have been used since prehistoric times. Their number, variety and geographic origin are considerable, and different substrates and agents including bacteria, yeasts and moulds have been used in their preparation. In the last few decades the scientific approach to the study of the participating microorganisms and the resulting products have provided a better understanding of their biological importance. Among the many health-related properties of fermented foods, effects on blood pressure have been described after casein hydrolysis by lactic acid bacteria. Peptides with antimicrobial activity, mainly against Gram-negative bacteria, and derived from casein have also been identified. This could explain, at least in part, the antidiarrheal effects of fermented products including those on traveler's diarrhea and against colonization by Helicobacter pylori. One of the best known advantages of fermented milk products is their capacity to improve lactose tolerance in hypolactasic subjects. With the growing prevalence of allergies and inflammatory bowel diseases, considerable interest has been focused on the effects of lactic acid bacteria in these conditions; there is evidence that these agents are associated with improvements in allergy; no such evidence exists for Crohn's disease or ulcerative colitis. A cholesterol-lowering capacity has also been described for some microorganisms. Not all the fermenting microorganisms have probiotic capacities as the latter are strain-specific.

Paraventricular-coerulear interactions: role in hypertension induced by prenatal undernutrition in the rat

Rats submitted to fetal growth retardation by in utero malnutrition develop hypertension when adult, showing increased hypothalamic mRNA expression for corticotropin-releasing hormone (CRH) and increased central noradrenergic activity. As hypothalamic CRH serves as an excitatory neurotransmitter within the locus coeruleus (LC) and coerulear norepinephrine plays a similar role within the paraventricular nucleus (PVN) of the hypothalamus, we studied, in both normal and prenatally undernourished 40-day-old anesthetized rats, the effects of intra-LC microinjection of CRH and intra-PVN microinjection of the alpha(1)-adrenoceptor antagonist prazosin on multiunit neuronal activity recorded simultaneously from the two nuclei, as well as the effects on systolic pressure. Undernutrition was induced during fetal life by restricting the diet of pregnant mothers to 10 g daily, whereas mothers of control rats received the same diet ad libitum. At day 40 of postnatal life: (i) undernourished rats showed increased neuronal activity in the PVN and LC, as well as increased systolic pressure; (ii) intra-LC CRH stimulated LC and PVN neurons and increased systolic pressure only in normal rats; (iii) intra-PVN prazosin decreased LC and PVN neuronal activity and systolic pressure only in undernourished rats; and (iv) in normal rats, prazosin prevented the stimulatory effect of CRH only in PVN activity; in undernourished rats, prazosin allowed CRH to regain its stimulatory effects. The results point to the existence of an excitatory PVN-LC closed loop, which seems to be hyperactive in prenatally undernourished rats as a consequence of fetal programming; this loop could be responsible, in part, for the hypertension developed by these animals.

Effect of regular ingestion of Saccharomyces boulardii plus inulin or Lactobacillus acidophilus LB in children colonized by Helicobacter pylori

AIM

To evaluate the effect of a probiotic, Lactobacillus acidophilus LB (LB), or a synbiotic, Saccharomyces boulardii plus inulin (SbI), on Helicobacter pylori (Hp) colonization in children.

SUBJECTS AND METHODS

A clinical trial was carried out in a school from a low socio-economic area of Santiago. Two hundred and fifty-four asymptomatic children (8.40+/-1.62 y) were screened for Hp by the (13)C-Urea Breath Test ((13)C-UBT). Hp-positive children were randomly distributed into three groups to receive either antibiotic treatment (lanzoprazole, clarythromycin and amoxicillin) for 8 d, or SbI or LB daily for 8 wk. A second (13)C-UBT was carried out at this time. Spontaneous clearance was evaluated in the same way in 81 infected, untreated children. The differences in the delta(13)CO(2) over baseline values before and after treatments (?DOB) were evaluated.

RESULTS

182 subjects (71.7%) were colonized by Hp, and 141 of them completed their treatment (22.5% dropout). Hp was eradicated in 66%, 12% and 6.5% of the children from the Ab, SbI and LB groups, respectively, while no spontaneous clearance was observed in the children without treatment. A moderate but significant difference in ?DOB was detected in children receiving living SbI (-6.31; 95% CI: -11.84 to -0.79), but not in those receiving LB (+0.70; 95% CI: -5.84 to +7.24).

CONCLUSION

S. boulardii seems promising as an agent that interferes with Hp in colonized individuals. More studies are needed to confirm these results and to elucidate the mechanisms by which Sb inhibits Hp.

Systematic review: are probiotics useful in controlling gastric colonization by Helicobacter pylori?

Helicobacter pylori is a highly prevalent pathogen considered as an aetiological factor for gastroduodenal ulcers, and a risk factor for gastric adenocarcinoma and lymphoma in humans. Most subjects colonized by this micro-organism are asymptomatic and remain untreated. In symptomatic patients, the antibiotic treatment has a high cost and is not 100% effective because of resistance to antibiotics and to moderate patient compliance. This review discusses the role of probiotics as alternative solutions to assist in the control of H. pylori colonization in at-risk populations. The evidence that some strains of Lactobacillus and Bifidobacterium are able to inhibit H. pylori growth through the release of bacteriocins or organic acids, and may also decrease its adhesion to epithelial cells, is reviewed. In addition, probiotics have a possible role in the stabilization of the gastric barrier function and the decrease of mucosal inflammation. Other aspects that are considered are the contribution of probiotics to the healing of the gastric mucosa linked to their antioxidant and anti-inflammatory properties. Clinical trials in colonized adults and children are reviewed, and suggest that probiotics do not eradicate H. pylori but maintain lower levels of this pathogen in the stomach; in combination with antibiotics, probiotics may increase eradication rate and/or decrease adverse effects. Papers suggesting similar effects on H. pylori by foodstuffs such as berry juice and some milk proteins are quoted. Regular intake of these and other dietary products might constitute a low-cost, large-scale alternative solution applicable for populations at-risk for H. pylori colonization.

Effect of a milk formula with prebiotics on the intestinal microbiota of infants after an antibiotic treatment

Antibiotics exert deleterious effects on the intestinal microbiota, favoring the emergence of opportunistic bacteria and diarrhea. Prebiotics are nondigestible food components that stimulate the growth of bifidobacteria. Our aim was to evaluate the effects on the intestinal microbiota of a prebiotic-supplemented milk formula after an antibiotic treatment. A randomized, double-blind, controlled clinical trial was carried out in 140 infants 1-2 y of age distributed into two groups after a 1-wk amoxicillin treatment (50 mg/kg/d) for acute bronchitis. The children received for 3 wk >500 mL/d of a formula with prebiotics (4.5 g/L) or a control without prebiotics. Fecal samples were obtained on d -7 (at the beginning of the antibiotic treatment), on d 0 (end of the treatment and before formula administration), and on d 7 and 21 (during formula administration). Counts of Bifidobacterium, Lactobacillus-Enterococcus, Clostridium lituseburiense cluster, Clostridium histolyticum cluster, Escherichia coli, and Bacteroides-Prevotella were evaluated by fluorescent in situ hybridization (FISH) and flow cytometry. Tolerance and gastrointestinal symptoms were recorded daily. Amoxicillin decreased total fecal bacteria and increased E. coli. The prebiotic significantly increased bifidobacteria from 8.17 +/- 1.46 on d 0 to 8.54 +/- 1.20 on d 7 compared with the control 8.22 +/- 1.24 on d 0 versus 7.95 +/- 1.54 on d 7. The Lactobacillus population showed a similar tendency while the other bacteria were unaffected. No gastrointestinal symptoms were detected during the prebiotic administration. Prebiotics in a milk formula increase fecal bifidobacteria early after amoxicillin treatment without inducing gastrointestinal symptoms.