Impact of polyunsaturated fatty acids on human colonic bacterial metabolism: an in vitro and in vivo study

Effect of dietary n-3 polyunsaturated fatty acids on the composition of cecal microbiome of Lohmann hens

Supplementation of n-3 fatty acids to poultry diets is widely acknowledged for its role in enhancing poultry products, however, little is known about the compositional responses of gut microbial communities to type and dosage of these supplements.  Here, we compared the effects of n-3 polyunsaturated fatty acids (PUFA), supplied as alpha-linolenic acid (ALA) or docosahexaenoic acid (DHA), on the composition of bacterial communities in ceca of laying hens.  Corn-soybean basal diets were supplemented with either flaxseed oil (FO, ALA-rich) or marine algal biomass (MA, DHA-rich), and each supplied 0.20 and 0.60% of total n-3 PUFA in the diet.  Lohmann LSL-Classic laying hens (n = 10/treatment) were randomly allocated to one of the 4 diets.  After 8 weeks of feeding, blood, liver and cecal digesta samples were obtained for plasma glucose, fatty acids, and short chain fatty acids analyses, respectively.  The gut bacterial communities were characterized using genomic DNA extracted from cecal contents, whereby the V3-V4 hypervariable region of the 16S rRNA gene was sequenced using the Illumina Miseq® platform.  Firmicutes and Bacteroidetes were the predominant phyla in both the FO- and MA-fed groups.  The relative abundance of Tenericutes, often associated with immunomodulation, was relatively higher (P<0.0001) in the FO than MA group.  Although the relative abundance of Bacteroides was greater for the FO- than the MA-fed group, this genus was negatively correlated (P<0.05) with total n-3 PUFA in the liver at higher dosages of both FO- and MA-fed hens.  Higher dose of FO (0.60%) and both dosages of MA (0.20 and 0.60%) substantially enriched several members of Firmicutes (e.g., Faecalibacterium, Clostridium and Ruminococcus) which are known to produce butyrate.  Moreover, co-occurrence network analysis revealed that, in the FO 0.60- and MA 0.20-fed hens, Ruminococcaceae was the most influential taxon accounting for about 31% of the network complexity.  These findings demonstrate that supplementation of different type and level of n-3 PUFA in hens' diets could enrich microbial communities with potential role in lipid metabolism and health.

Metabolomic Evaluation of Scenedesmus sp. as a Feed Ingredient Revealed Dose-Dependent Effects on Redox Balance, Intermediary and Microbial Metabolism in a Mouse Model

Scenedesmus is a common green algae genus with high biomass productivity, and has been widely used in biofuel production and waste water management. However, the suitability and metabolic consequences of using Scenedesmus as an animal feed ingredient have not been examined in detail. In this study, the influences of consuming Scenedesmus on the metabolic status of young mice were investigated through growth performance, blood chemistry, and liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. Compared to the control diet, feeding a diet containing 5% Scenedesmus improved growth performance while the diet containing 20% Scenedesmus suppressed it. Among common macronutrients-derived blood biochemicals, serum triacylglycerols and cholesterol levels were dramatically decreased by feeding the 20% Scenedesmus diet. Metabolomic analysis of liver, serum, feces, and urine samples indicated that Scenedesmus feeding greatly affected the metabolites associated with amino acid, lipid, purine, microbial metabolism, and the endogenous antioxidant system. The growth promotion effect of feeding the 5% Scenedesmus diet was associated with elevated concentrations of antioxidants, an expanded purine nucleotide cycle, and modified microbial metabolism, while the growth suppression effect of feeding the 20% Scenedesmus diet was correlated to oxidative stress, disrupted urea cycle, upregulated fatty acid oxidation, and an imbalanced lipidome. These correlations among Scenedesmus dietary inclusion rate, individual metabolite markers, and growth performance suggest the need to define the dietary inclusion rate threshold for using Scenedesmus and other microalgae supplements as feed ingredients, and also warrant further mechanistic investigations on the biological processes connecting specific constituents of Scenedesmus with the metabolic effects observed in this study.

Diet, the intestinal microbiota, and immune health in aging

Many countries are facing aging populations, with those over 65 years of age likely to represent the largest population over the next 10-20 years. Living longer often comes with poor health and, in particular, a decline in the immune function characterized by poor vaccine responses and increased risk of infection and certain cancers. Aging and diet represent major intrinsic and extrinsic factors that influence the makeup and activity of resident intestinal microbes, the microbiota, the efficient functioning of which is essential for sustaining overall health and the effectiveness of the immune system. The provision of elderly specific dietary recommendations appears to be lacking but is necessary since this population has an altered microbiota and immune response and may not respond in the same way as their healthy and younger counterparts. We have reviewed the evidence supporting the role of diet and, in particular, dietary carbohydrate, protein, and fat in influencing the microbiota and its generation of key metabolites that influence the efficient functioning of immune cells during aging, and how dietary intervention might be of benefit in improving the intestinal health and immune status in the elderly.

Advances in Gut Microbiome Research, Opening New Strategies to Cope with a Western Lifestyle

The "westernization" of global eating and lifestyle habits is associated with the growing rate of chronic diseases, mainly cardiovascular diseases, cancer, type 2 diabetes mellitus, and respiratory diseases. The primary prevention approach is to make nutritional and behavioral changes, however, there is another important determinant of our health that only recently has been considered and is the presence of beneficial microorganisms and their products in our gastrointestinal tract. Microorganisms living in our body can alter the fate of food, drugs, hormones, and xenobiotics, and recent studies point to the use of microorganisms that can counteract the harmful effects of certain compounds introduced or produced endogenously in our body. This review considers the effects of the western lifestyle on adiposity, glucose metabolism, oxidative markers and inflammation profile, emphasizes on the studies that have investigated bacterial strains and products of their metabolism that are beneficial under this lifestyle, and examines the screening strategies that recent studies are using to select the most promising probiotic isolates. In addition, we consider the relevance of studying the microbiota of metabolically healthy people under a western lifestyle for the understanding of the key components that delay the development of chronic diseases.

A host-microbiome interaction mediates the opposing effects of omega-6 and omega-3 fatty acids on metabolic endotoxemia

Metabolic endotoxemia, commonly derived from gut dysbiosis, is a primary cause of chronic low grade inflammation that underlies many chronic diseases. Here we show that mice fed a diet high in omega-6 fatty acids exhibit higher levels of metabolic endotoxemia and systemic low-grade inflammation, while transgenic conversion of tissue omega-6 to omega-3 fatty acids dramatically reduces endotoxemic and inflammatory status. These opposing effects of tissue omega-6 and omega-3 fatty acids can be eliminated by antibiotic treatment and animal co-housing, suggesting the involvement of the gut microbiota. Analysis of gut microbiota and fecal transfer revealed that elevated tissue omega-3 fatty acids enhance intestinal production and secretion of intestinal alkaline phosphatase (IAP), which induces changes in the gut bacteria composition resulting in decreased lipopolysaccharide production and gut permeability, and ultimately, reduced metabolic endotoxemia and inflammation. Our findings uncover an interaction between host tissue fatty acid composition and gut microbiota as a novel mechanism for the anti-inflammatory effect of omega-3 fatty acids. Given the excess of omega-6 and deficiency of omega-3 in the modern Western diet, the differential effects of tissue omega-6 and omega-3 fatty acids on gut microbiota and metabolic endotoxemia provide insight into the etiology and management of today's health epidemics.

Panacea seed "Nigella": A review focusing on regenerative effects for gastric ailments

Nigella sativa (NS) or black cumin is a dark, thin, and crescent-shaped, seeded shrub belonging to the Ranunculaceae family commonly growing on Mediterranean coasts in Saudi Arabia, northern Africa and Asia. They have amazing curative and therapeutic features that make them one of the most popular, safe, non-detrimental, and cytoprotective medicinal plant that can be used for prevention and treatment of many complicated diseases. Originally, N. sativa was used to treat migraines and allergy, and researches have shown its effectiveness in destroying cancer cells as well. The gastro protective effect of NS oil and its constituents has also been reported earlier; however, the complete perception on etiology and pathogenesis of gastric ulcer is not yet clear. Herein, we attempt to unveil some of the potential mechanisms exhibited by NS in preventing problems related to gastric ulcers. Gastric ailments like ulcers and tumors are the most common disorders of the gastro-intestinal tract in the present day life of the industrialized world. Gastric ulcer being a multifaceted problem exhibits complex etiology and is the fourth most common cause of cancer mortality. Drug interactions and toxicity are the main hindrances in chemotherapy. The existing merits and demerits of modern-day drugs make us turn toward the plant kingdom which may provide a valuable resource of novel potent natural compounds for pharmaceuticals or alternately, as dietary supplements. In this context, the revered phytotherapeutic N. sativa comes as a promising savior in today’s times. This review aims to summarize, both the functional and disease-related effects in the area of gastroenterology.

Adiposity, gut microbiota and faecal short chain fatty acids are linked in adult humans

BACKGROUND/OBJECTIVES

High dietary fibre intakes may protect against obesity by influencing colonic fermentation and the colonic microbiota. Though, recent studies suggest that increased colonic fermentation contributes to adiposity. Diet influences the composition of the gut microbiota. Previous research has not evaluated dietary intakes, body mass index (BMI), faecal microbiota and short chain fatty acid (SCFA) in the same cohort. Our objectives were to compare dietary intakes, faecal SCFA concentrations and gut microbial profiles in healthy lean (LN, BMI⩽25) and overweight or obese (OWOB, BMI>25) participants.

DESIGN

We collected demographic information, 3-day diet records, physical activity questionnaires and breath and faecal samples from 94 participants of whom 52 were LN and 42 OWOB.

RESULTS

Dietary intakes and physical activity levels did not differ significantly between groups. OWOB participants had higher faecal acetate (P=0.05), propionate (P=0.03), butyrate (P=0.05), valerate (P=0.03) and total short chain fatty acid (SCFA; P=0.02) concentrations than LN. No significant differences in Firmicutes to Bacteroides/Prevotella (F:B) ratio was observed between groups. However, in the entire cohort, Bacteroides/Prevotella counts were negatively correlated with faecal total SCFA (r=-0.32, P=0.002) and F:B ratio was positively correlated with faecal total SCFA (r=0.42, P<0.0001). Principal component analysis identified distinct gut microbiota and SCFA-F:B ratio components, which together accounted for 59% of the variation. F:B ratio loaded with the SCFA and not with the microbiota suggesting that SCFA and F:B ratio vary together and may be interrelated.

CONCLUSIONS

The results support the hypothesis that colonic fermentation patterns may be altered, leading to different faecal SCFA concentrations in OWOB compared with LN humans. More in-depth studies looking at the metabolic fate of SCFA produced in LN and OWOB participants are needed in order to determine the role of SCFA in obesity.

Clinical trial: marine lipid suppositories as laxatives

Cod-liver oil and other marine products containing polyunsaturated fatty acids have anti-inflammatory, anti-bacterial and anti-viral effects and may be useful in the treatment of various inflammatory and infectious diseases. We developed suppositories and ointment with 30% free fatty acid (FFA) extract from omega-3 fish oil. Our purpose was to evaluate the safety of marine lipid suppositories and ointment in healthy volunteers and to explore the laxative effect of the suppositories. Thirty healthy volunteers were randomized either to a study group administrating 30% FFA suppositories and applying 30% FFA ointment to the perianal region twice per day for two weeks, or to a control group using placebo suppositories and ointment in a double blinded manner. Results: No serious toxic effects or irritation were observed. In the study group 93% felt the urge to defecate after administration of the suppositories as compared to 37% in the control group (P = 0.001). Subsequently 90% in the study group defecated, compared to 33% in the control group (P = 0.001). Conclusion: The marine lipid suppositories and ointment were well tolerated with no significant toxic side effects observed during the study period. The suppositories have a distinct laxative effect and we aim to explore this effect in further clinical trials.

Gut bacteria profiles of Mus musculus at the phylum and family levels are influenced by saturation of dietary fatty acids

BACKGROUND

Mammalian gut microbiota have been implicated in a variety of functions including the breakdown of ingested nutrients, the regulation of energy intake and storage, the control of immune system development and activity, and the synthesis of novel chemicals. Previous studies have shown that feeding mammalian hosts a high-fat diet shifts gut bacteria at the phylum level to reduce the ratio of Bacteroidetes-to-Firmicutes, while feeding hosts a fat-restricted diet increases this ratio. However, few studies have investigated the differential effects of fatty acid type on gut bacterial profile.

METHODS

Over a 14-week period, Mus musculus were fed a diet rich in omega-3 polyunsaturated fatty acids (n-3 PUFAs), omega-6 polyunsaturated fatty acids (n-6 PUFAs), or saturated fatty acids (SFAs). Fecal pellets were collected before and after the treatment period from 12 randomly selected mice (4 per treatment group). Bacterial DNA was extracted from the pellets and characterized by analysis of the hypervariable V3 region of the 16S rRNA. Nominal logistic regression models were used to assess shifts in microbial profile at the phylum and family levels in response to diet.

RESULTS

A significant decrease in the proportion of phylum Bacteroidetes species was observed for mice fed any of the three diets over time. However, the SFA-rich diet group showed a significantly greater decrease in Bacteroidetes proportion (-28%) than did either the n-3 PUFA group (-10%) or the n-6 PUFA group (-12%). At the family level, a significant decrease in proportion of Porphyromonadaceae was observed for mice fed the n-6 PUFA-rich diet, and a significant decrease in proportion of Lachnospiraceae was observed for mice fed the SFA-rich diet. There was no significant effect of diet type on body mass change.

CONCLUSION

Our results indicate that SFAs have stronger effects than PUFAs in shifting gut microbiota profiles toward those typical of obese individuals, and that dietary fatty acid saturation influences shifts in gut microbiota independently of changes in body mass.

Dietary long-chain n-3 PUFA, gut microbiota and fat mass in early postnatal piglet development--exploring a potential interplay

Dietary n-3PUFA and gut bacteria, particularly Bacteroidetes, have been suggested to be related to adiposity. We investigated if n-3PUFA affected fat storage and cecal bacteria in piglets. Twenty-four 4-day-old piglets were allocated to formula rich in n-3PUFA (∼3E%) from fish oil (FO) or n-6PUFA from sunflower oil (SO) for 14 days. We assessed body weight, fat accumulation by dual-energy X-ray absorptiometry and microbial molecular fingerprints. Dietary PUFA-composition was reflected in higher erythrocyte n-3PUFA in the FO- than the SO-group (P<0.001). Principal component analysis revealed group differences in the overall microbiotic composition, which involved a larger Bacteroides community in the SO-group (P=0.02). There was no significant difference in body fat percentage and no relationship between fat accumulation and gut Bacteroides. Hence, this study does not support an impact of n-3PUFA or microbiota on fat accumulation during the postnatal maturation period. The impact of dietary PUFA on the gut Bacteroides warrants further investigation.

Molecular fingerprints of the human fecal microbiota from 9 to 18 months old and the effect of fish oil supplementation

OBJECTIVES

The aim of this study was to monitor changes in the fecal microbiota from 9 to 18 months and to investigate the effect of increasing dietary n-3 polyunsaturated fatty acids on the fecal microbiota.

PATIENTS AND METHODS

In a double-blind controlled trial with random allocation to daily supplementation with 5 mL of fish oil (FO) or sunflower oil (SO) from 9 to 18 months of age, stool samples were collected from 132 healthy Danish infants. Molecular fingerprints of the bacterial DNA were obtained by terminal restriction fragment length polymorphism (T-RFLP).

RESULTS

The T-RFLP profiles indicated that a few T-RFs became dominant with age (bp100 and 102, both presumed to be Bacteroidetes) concomitantly with an overall increase in the microbial diversity (P = 0.04). Breast-feeding influenced both the T-RFLP profiles at 9 months and the changes from 9 to 18 months, and breast-feeding cessation during the trial modified the response to the dietary oils. In the FO group, the increase in bp102 was significantly reduced among children weaned before compared with those weaned during the trial (P = 0.027), whereas the increase in bp100 was reduced in the preweaned children of the SO group relative to those weaned during the trial (P = 0.004). This was supported by intervention group differences in the changes in bp102 and bp100 among the earlier weaned children (P = 0.06 and P = 0.09, respectively).

CONCLUSIONS

Cessation of breast-feeding played a dominant role relative to developmental changes in the fecal microbiota from 9 to 18 months. FO compared with SO supplementation affected changes in large bacterial groups, but only among children who had stopped breast-feeding before 9 months of age.

Involvement of gut microbial fermentation in the metabolic alterations occurring in n-3 polyunsaturated fatty acids-depleted mice

Backround

Western diet is characterized by an insufficient n-3 polyunsaturated fatty acid (PUFA) consumption which is known to promote the pathogenesis of several diseases. We have previously observed that mice fed with a diet poor in n-3 PUFA for two generations exhibit hepatic steatosis together with a decrease in body weight. The gut microbiota contributes to the regulation of host energy metabolism, due to symbiotic relationship with fermentable nutrients provided in the diet. In this study, we have tested the hypothesis that perturbations of the gut microbiota contribute to the metabolic alterations occurring in mice fed a diet poor in n-3 PUFA for two generations (n-3/- mice).

Methods

C57Bl/6J mice fed with a control or an n-3 PUFA depleted diet for two generations were supplemented with prebiotic (inulin-type Fructooligosaccharides, FOS, 0.20 g/day/mice) during 24 days.

Results

n-3/-mice exhibited a marked drop in caecum weight, a decrease in lactobacilli and an increase in bifidobacteria in the caecal content as compared to control mice (n-3/+ mice). Dietary supplementation with FOS for 24 days was sufficient to increase caecal weight and bifidobacteria count in both n-3/+ and n-3/-mice. Moreover, FOS increased lactobacilli content in n-3/-mice, whereas it decreased their level in n-3/+ mice. Interestingly, FOS treatment promoted body weight gain in n-3/-mice by increasing energy efficiency. In addition, FOS treatment decreased fasting glycemia and lowered the higher expression of key factors involved in the fatty acid catabolism observed in the liver of n-3/-mice, without lessening steatosis.

Conclusions

the changes in the gut microbiota composition induced by FOS are different depending on the type of diet. We show that FOS may promote lactobacilli and counteract the catabolic status induced by n-3 PUFA depletion in mice, thereby contributing to restore efficient fat storage.

Duodenal administered seal oil for patients with subjective food hypersensitivity: an explorative open pilot study

Short-term duodenal administration of n-3 polyunsaturated fatty acid (PUFA)-rich seal oil may improve gastrointestinal complaints in patients with subjective food hypersensitivity, as well as joint pain in patients with inflammatory bowel disease (IBD). The aim of the present explorative pilot study was to investigate whether 10-day open treatment with seal oil, 10 mL self-administrated via a nasoduodenal tube 3 times daily, could also benefit nongastrointestinal complaints and quality of life (QoL) in patients with subjective food hypersensitivity. Twenty-six patients with subjective food hypersensitivity, of whom 25 had irritable bowel syndrome (IBS), were included in the present study. Before and after treatment and 1 month posttreatment, patients filled in the Ulcer Esophagitis Subjective Symptoms Scale (UESS) and the Gastrointestinal Symptom Rating Scale (GSRS) for gastrointestinal symptoms and subjective health complaints (SHC) inventory for nongastrointestinal symptoms in addition to short form of the Nepean dyspepsia index (SF-NDI) for evaluation of QoL. Compared with baseline, gastrointestinal, as well as nongastrointestinal, complaints and QoL improved significantly, both at end of treatment and 1 month posttreatment. The consistent improvements following seal oil administration warrant further placebo-controlled trials for confirmation of effect.

Impact of diet on the intestinal microbiota in 10-month-old infants

OBJECTIVE

To investigate whether diet influences the composition of the intestinal microbiota in 10-month-old infants.

PATIENTS AND METHODS

Fecal samples were collected from sixty-five 10-month-old infants participating in a randomized 2 x 2 intervention study comparing cow's milk (CM) with infant formula (IF) with or without fish oil (FO) supplement. Infants randomized to CM received a daily iron supplement. Bacterial DNA was extracted from the feces. Polymerase chain reaction was performed with primers targeting the V3 and V6-8 region of the 16S rRNA gene and analyzed by denaturing gradient gel electrophoresis (DGGE). Cluster analysis of the DGGE gels was performed by use of the Pearson correlation coefficient.

RESULTS

Samples from infants receiving CM clustered differently than did those from the IF group in the V3-based DGGE gels (P < 0.001) and showed a different distribution with or without FO in the CM group (P = 0.001) but not in the IF group (P = 0.39). Repeat analysis with the V6-8-based DGGE gels showed the same pattern, although the V3 gels had 2.5 times as many bands as the V6-8 gels.

CONCLUSIONS

Consumption of CM or IF has a decisive influence on the composition of the intestinal microbiota. Supplementation with FO showed an effect on the microbiota only in the CM group. We speculate that these differences could be influenced by the intake of iron and n-3 polyunsaturated fatty acids, respectively.

Major depressive disorder: probiotics may be an adjuvant therapy

Major depressive disorder (MDD) is an extremely complex and heterogeneous condition. Emerging research suggests that nutritional influences on MDD are currently underestimated. MDD patients have been shown to have elevated levels of pro-inflammatory cytokines, increased oxidative stress, altered gastrointestinal (GI) function, and lowered micronutrient and omega-3 fatty acid status. Small intestinal bacterial overgrowth (SIBO) is likely contributing to the limited nutrient absorption in MDD. Stress, a significant factor in MDD, is known to alter GI microflora, lowering levels of lactobacilli and bifidobacterium. Research suggests that bacteria in the GI tract can communicate with the central nervous system, even in the absence of an immune response. Probiotics have the potential to lower systemic inflammatory cytokines, decrease oxidative stress, improve nutritional status, and correct SIBO. The effect of probiotics on systemic inflammatory cytokines and oxidative stress may ultimately lead to increased brain derived neurotrophic factor (BDNF). It is our contention that probiotics may be an adjuvant to standard care in MDD.

The intestinal mucosa as a target for dietary polyunsaturated fatty acids

Several studies have reported beneficial effects of dietary polyunsaturated fatty acids (PUFA) on various aspects of both human and animal health, and particular reference has been made to their effects on systemic immune responses. Both immune stimulation and immune suppression have been reported, with the outcome dependent on the type of PUFA, the target cell, as well as the immune competence of the cells before exposure. The systemic and the mucosal immune systems are discrete entities, which have evolved specific approaches in the defense of the host. The latter comprises several interconnected tissues, which communicate with one another through the action of soluble mediators and the trafficking of cellular components. After the oral mucosa, the intestinal epithelium and its associated gut-associated lymphoid tissue are the primary targets of dietary components. Absorption of dietary PUFA and its incorporation into intestinal tissues has been well studied, but the consequences of these events in relation to local immune responses have received little attention. This article describes some of the immune mechanisms operating at this barrier and, where possible, pinpoints areas for which a modulatory role for PUFA has already been demonstrated. Although not an exhaustive treatise of the subject, it is hoped that this review will foster research into the specific interaction between dietary PUFA and cell populations comprising the intestinal barrier.

Review: the role of omega 3 fatty acids in intestinal inflammation

The role of polyunsaturated fatty acids (PUFAs) in inflammatory lesions of the intestines is the subject of increasing research. This review begins with a background discussion of the source, elongation, and desaturation of PUFAs, as well as the role they have played in the human diet through evolution. The available data and hypotheses as to how manipulation of PUFAs might effect the various components of the immune system are then provided. Possible mechanisms by which PUFAs result in immunomodulation include alterations in eicosanoid synthesis, membrane fluidity, signal transduction, intraluminal bacteria, and gene expression. Attention is then turned to the known effects that these polyunsaturated fatty acids have on the various individual components of the immune system including lymphocytes, neutrophils, and antigen presenting cells, as well as the immunoregulatory process of apoptosis. Finally, laboratory data on the role of PUFAs in necrotizing enterocolitis, and to a greater extent inflammatory bowel disease, first as demonstrated in animal models of the disease, and second in human studies are then summarized.