Flaxseed gum reduces body weight by regulating gut microbiota

Seed mucilage-based advanced carrier systems for food and nutraceuticals: fabrication, formulation efficiency, recent advancement, challenges, and perspectives

Seed mucilages are potential sources of natural polysaccharides. They are biodegradable, biocompatible, sustainable, renewable, and safe for human consumption. Due to the desirable physicochemical and functional properties (e.g. gelling, thickening, stabilizing, and emulsifying), seed mucilages have attracted extensive attention from researchers for utilization as a promising material for the development of advanced carrier systems. Seed mucilages have been utilized as natural polymers to improve the properties of various carrier systems (e.g. complex coacervates, beads, nanofibers, and gels) and for the delivery of diverse hydrophilic and lipophilic compounds (e.g. vitamins, essential oils, antioxidants, probiotics, and antimicrobial agents) to achieve enhanced stability, bioavailability, bioactivity of the encapsulated molecules, and improved quality attributes of food products. This review highlights the recent progress in seed mucilage-based carrier systems for food and nutraceutical applications. The main contents include (1) sources, extraction methods, and physicochemical and functional characteristics of seed mucilages, (2) application of seed mucilages for the development of advanced carrier systems, (3) major issues associated with carrier fabrication, and (4) mechanisms of carrier development, latest improvements in carrier formulation, carrier efficiency in the delivery of bioactive agents, and application in food and nutraceuticals. Furthermore, major challenges and future perspectives of seed mucilage-based carriers for a commercial application are discussed.

Metabolites of Clostridium leptum fermenting flaxseed polysaccharide alleviate obesity in rats

Obesity is a chronic metabolic disease. Our previous research found flaxseed polysaccharide (FP) has an anti-obesity effect, and its anti-obesity effect possibly depends on Clostridium leptum (C. leptum). However, whether the strain takes the role and how it works is still being determined. Here, FP was fermented in vitro by C. leptum and its metabolites were analyzed. Subsequently, the FP fermentation broth of C. leptum (FPF) was given to the obese pseudo sterile rats. The results showed FPF was rich in various metabolites, among which the top ten in relative expression abundance were 3 beta-hydroxy-5-cholestenoate, 7,8-dihydro-3b,6a-dihydroxy-alpha-ionol 9-glucoside, Valyl-Serine, 2-amino-4-[(2-hydroxy-1-oxopropyl)amino]butanoic acid, Agavoside B, glycylproline, lycopersiconolide, armillaritin, Isoleucyl-Hydroxyproline and norethindrone acetate. After intervention with FPF, the weight, abdominal fat ratio, and total fat ratio of rats were significantly reduced and the lipid metabolism of them has been improved. This effect may be achieved by up regulating glucagon-like peptide-1 and adiponectin and further activating the AMP-activated protein kinase signaling pathway. This is the first experimental proof that FP exerts its anti-obesity effects through metabolites from C. leptum fermenting FP, not FP itself and the bacterial cells (debris) of C. leptum. It is also the first demonstration that FPF has a significant anti-obesity effect.

Unveiling the potential of linseed mucilage, its health benefits, and applications in food packaging

Industrial waste products derived from the oil industry often contain valuable substances and elements with great potential. These by-products can be used for various purposes, including as nutrients, bioactive compounds, fuels, and polymers. Linseed mucilage (LM) is one such example of a beneficial by-product obtained from linseed. It possesses favorable chemical and functional properties, depending on its method of extraction. Different pretreatments, such as enzymatic extraction, microwave-assisted extraction, pulse electric field, and ultrasound-assisted extraction, have been explored by various researchers to enhance both the yield and quality of mucilage. Furthermore, LM has exhibited therapeutic effects in the treatment of obesity, diabetes, constipation, hyperlipidemia, cancer, and other lifestyle diseases. Additionally, it demonstrates favorable functional characteristics that make it suitable to be used in bioplastic production. These properties preserve food quality, prolong shelf life, and confer antimicrobial activity. It also has the potential to be used as a packaging material, especially considering the increasing demand for sustainable and biodegradable alternatives to plastics because of their detrimental impact on environmental health. This review primarily focuses on different extraction techniques used for linseed mucilage, its mechanism of action in terms of health benefits, and potential applications in food packaging.

New horizon to the world of gut microbiome: seeds germination

The second brain of humans has been known as the microbiome. The microbiome is a dynamic network composed of commensal bacteria, archaea, viruses, and fungi colonized in the human gastrointestinal tract. They play a vital role in human health by metabolizing components, maturation of the immune system, and taking part in the treatment of various diseases. Two important factors that can affect the gut microbiome's composition and/or function are the food matrix and methods of food processing. Based on scientific research, the consumption of whole grains can make positive changes in the gut microbiota. Seeds contain different microbiota-accessible substrates that can resist digestion in the upper gastrointestinal tract. Seed germination is one of the simplest and newest food processing approaches to improve seeds' bioavailability and overall nutritional value. During germination, the dormant hydrolytic seed's enzymes have been activated and then metabolize the macromolecules. The quality and quantity of bioactive compounds like prebiotics, fiber, phenolic compounds (PC), total free amino acids, and γ-aminobutyric acid (GABA) can increase even up to 4-10 folds in some cases. These components stimulate the survival and growth of healthful bacteria like probiotics and boost their activity. This effect depends on several parameters, e.g., germination environmental conditions. This review aims to provide up-to-date and latest research about promoting bioactive components during seed germination and investigating their impacts on gut microbiota to understand the possible direct and indirect effects of seed germination on the microbiome and human health.

Effect of Flaxseed Gum on the Textural, Rheological, and Tribological Properties of Acid-Induced Soy Protein Isolate Gels

This study aimed to investigate the effects of incorporating different concentrations of flaxseed gum (FG) into acid-induced soy protein isolate (SPI) gels. The investigation focused on assessing the effects of FG on the textural, rheological, and tribological properties of the resultant SPI gels. The results showed that adding a small amount of FG (0.05%) to the SPI gel system increased the storage modulus (G') and enhanced gelation while improving textural properties including hardness, viscosity, elasticity, and adhesion. Moreover, these gels exhibited strong water-holding capacity, a desirable property in various food products. However, when the concentration was increased to 0.3%, the WHC of the gel decreased, as did the hardness and cohesiveness. The particle size of the gel also increased with increasing concentration. Tribological investigations revealed that at 0.05-0.2% FG addition, the coefficient of friction (μ) of the composite gel was decreased compared to the pure SPI gel. In the sliding speed range of 1-100 mm/s, the coefficient of friction gradually increased with increasing concentration. When the FG concentration was 0.05%, the μ of the gel system was the lowest. In summary, low concentration of FG (0.05%) was found to play an important role in improving the properties of SPI gel, including enhancing textural, rheological, and lubricating properties.

Endocrine Disruptors in Food, Estrobolome and Breast Cancer

The microbiota is now recognized as one of the major players in human health and diseases, including cancer. Regarding breast cancer (BC), a clear link between microbiota and oncogenesis still needs to be confirmed. Yet, part of the bacterial gene mass inside the gut, constituting the so called "estrobolome", influences sexual hormonal balance and, since the increased exposure to estrogens is associated with an increased risk, may impact on the onset, progression, and treatment of hormonal dependent cancers (which account for more than 70% of all BCs). The hormonal dependent BCs are also affected by environmental and dietary endocrine disruptors and phytoestrogens which interact with microbiota in a bidirectional way: on the one side disruptors can alter the composition and functions of the estrobolome, ad on the other the gut microbiota influences the metabolism of endocrine active food components. This review highlights the current evidence about the complex interplay between endocrine disruptors, phytoestrogens, microbiome, and BC, within the frames of a new "oncobiotic" perspective.

Protein Fractions from Flaxseed: The Effect of Subsequent Extractions on Composition and Antioxidant Capacity

Flaxseed proteins exhibit functionalities interesting for the food industry, including antioxidant capacity. Antioxidant activity depends on the protein composition and the presence of phenolic compounds extracted with them from the matrix. The research focused on the effect of subsequent protein extractions (water, salt and alkaline) of flaxseed meals (of three cultivars) on the protein fraction composition and its relations to antioxidant capacity. The protein and phenolic profiles and antioxidant functionalities (in antiradical ORAC and emulsion assays) were analysed. Spectroscopic characteristics of the fractions (fluorometric and FT-IR analysis) were also included. Our study has shown the effect of fractionation on the share of proteins at MW from 56-38 kDa (globulin-like) and <15 kDa (albumin-like) in the protein profiles. The highest globulin share was in the alkaline-extracted fractions (AEF) and albumin in the salt-extracted (SEF) ones. SDG (secoisolariciresinol diglucosides) and phenolic acids (p-coumaric and ferulic) were extracted with flaxseed proteins. Their contents were fraction-dependent and the highest in AEF. The concentration of phenolics in AEF corresponded with the highest antiradical capacity (ORAC) compared with the other fractions. However, the SEF showed a higher ability to inhibit oxidation in emulsions than AEF, which could be associated with the higher content of the low MW proteins.

Study of Varietal Differences in the Composition of Heteropolysaccharides of Oil Flax and Fiber Flax

Flaxseed mucilage and its derivatives have been extensively investigated over the last decade, mainly due to their inherent techno-functional (thickening, gelling, interface-stabilizing, and film-forming) properties that are relevant in the food industry. Hydrocolloids are used to modify food properties, such as for stabilization and emulsion, and are also used to control the microstructure of the food. Increasing research attention has been paid to the application of hydrocolloid materials in gel particles for encapsulation or texture control in food, pharmaceutical, cosmetic, and probiotic products. Thus, it is important to investigate the properties of hydrocolloids manufactured from various sources and explore their possible applications in the food industry. The applied nature of the study of plant mucus substances is associated with the ever-increasing demand for their use in the food, cosmetic, and pharmacological industries, determining the related research priorities, including the development of the most effective methods for the extraction of glycans and the search for highly productive raw materials for the production of polysaccharides. The aim of this work was to study varietal differences in the compositions of heteropolysaccharides in the mucus samples of oilseed and fiber flax varieties using a modern methodological approach for obtaining glycans based on the ultrasonic extraction of polysaccharides. The seeds of 10 flax varieties were studied, differing in their morphotype, place, and time of creation. The obtained results indicated significant differences in the quantitative and qualitative compositions of the heteropolysaccharides of flax seeds of various varieties. The contents of reducing sugars in the studied varieties ranged from 5.61 ± 0.01 to 18.81 ± 0.01 mg/g, indicating significant differences in the structural organization of glycans in different flax varieties. Additionally, the results obtained here allowed us to conclude that the range of reducing sugars for flax heteropolysaccharides is significantly less than this range for oilseed flax varieties. The obtained results of the study of the composition of flax seed heteropolysaccharides allowed us to consider them as selection trait and genetic markers.

Fabrication and Characterization of Botanical-Based Double-Layered Emulsion: Protection of DHA and Astaxanthin Based on Interface Remodeling

Both DHA and astaxanthin, with multiple conjugated double bonds, are considered as health-promoting molecules. However, their utilizations into food systems are restricted due to their poor water solubility and high oxidizability, plus their certain off-smell. In this study, the interactions between perilla protein isolate (PPI) and flaxseed gum (FG) were firstly investigated using multiple spectroscopies, suggesting that hydrophobic, electrostatic force and hydrogen bonds played important roles. Additionally, double-layer emulsion was constructed by layer-by-layer deposition technology and exhibited preferable effects on masking the fishy smell of algae oil. Calcium ions also showed an improving effect on the elasticity modulus of O/W emulsions and was managed to significantly protect the stability of co-delivered astaxanthin and DHA, without additional antioxidants during storage for 21 days. The vegan system produced in this study may, therefore, be suitable for effective delivery of both ω-3 fatty acid and carotenoids for their further incorporation into food systems, such as plant-based yoghourt, etc.

Flaxseed Bioactive Compounds: Chemical Composition, Functional Properties, Food Applications and Health Benefits-Related Gut Microbes

Flaxseed (Linum usitatissimum L.) has gained worldwide recognition as a health food because of its abundance in diverse nutrients and bioactive compounds such as oil, fatty acids, proteins, peptides, fiber, lignans, carbohydrates, mucilage, and micronutrients. These constituents attribute a multitude of beneficial properties to flaxseed that makes its use possible in various applications, such as nutraceuticals, food products, cosmetics, and biomaterials. The importance of these flaxseed components has also increased in modern times because of the newer trend among consumers of greater reliance on a plant-based diet for fulfilling their nutritional requirements, which is perceived to be hypoallergenic, more environmentally friendly, sustainable, and humane. The role of flaxseed substances in the maintenance of a healthy composition of the gut microbiome, prevention, and management of multiple diseases has recently been elucidated in various studies, which have highlighted its importance further as a powerful nutritional remedy. Many articles previously reported the nutritive and health benefits of flaxseed, but no review paper has been published reporting the use of individual flaxseed components in a manner to improve the techno-functional properties of foods. This review summarizes almost all possible applications of flaxseed ingredients in food products from an extensive online literature survey; moreover, it also outlines the way forward to make this utilization even better.

The effect of flaxseed intake on appetite reduction: A systematic review of randomized clinical trials

Appetite control has attracted many scientists' attention recently since it can lead to weight management and the prevention of further metabolic disorders. Many studies have been carried out to assess the effect of flaxseed on satiety perception but the results are controversial. This study aims to review these results comprehensively. PubMed/Medline, Web of Science, Scopus, and Cochrane databases were searched for related papers on June 2021. The searched keywords for appetite were: visual analog scale, appetite, desire to eat, satiation, satiety, hunger, fullness, and for Flaxseed they were: flax, flax*, linseed*, lignin*, Linseed Oil, flaxseed, ground flaxseed, flaxseed oil, and Linum usitatissimum. The 13 included studies were inconsistent in results and some of them found no significant effect of flaxseed on the considered outcomes. However, three studies revealed a significant reduction in hunger perception as well as appetite. Moreover, two studies found a decreasing effect on prospective consumption. Three studies observed a positive significant effect on fullness and satiety. Although there are a limited number of documents related to the effect of flaxseed on appetite perception, or its equivalent terms, the available studies suggest the potential role of flaxseed in decreasing appetite and hunger.

Structural Characterization and Functional Properties of Flaxseed Hydrocolloids and Their Application

Flaxseed is an excellent source of valuable nutrients and is also considered a functional food. There are two types of hydrocolloids in flaxseed: flaxseed gum and proteins. Flaxseed gum exhibits emulsifying and foaming activities or can be used as a thickening and gelling agent. Due to its form of soluble fiber, flaxseed gum is related to many health benefits. Flaxseed proteins have various functional properties based on their physicochemical properties. While albumins possess the emulsion-forming ability, globulins better serve as foaming agents. Flaxseed proteins may also serve as a source of functional peptides with interesting biological and health-related activities. Functional properties and health-related benefits predetermine the application of these hydrocolloids, mainly in the food industry or medicine. Although these properties of flaxseed hydrocolloids have been recently and extensively studied, they are still not widely used on the industrial scale compared to other popular plant gums and proteins. The aim of this review was to present, discuss and highlight the recent discoveries in the structural characteristics and functional and biological properties of these versatile hydrocolloids with respect to factors affecting their characteristics and offer new insights into their potential applications as comparable alternatives to the other natural hydrocolloids or as the sources of novel functional products.

Flaxseed Polysaccharide Alters Colonic Gene Expression of Lipid Metabolism and Energy Metabolism in Obese Rats

Obesity is one of the most serious public health challenges. Recently, we found that flaxseed polysaccharides (FPs) had an anti-obesity effect through promoting lipid metabolism, but the obesity-inhibiting pathway of FP is still unclear. In this study, after FP intervention in an obese rat model, a transcriptome study was performed to further investigate how FP intervention alters the gene expression of colonic epithelial tissues (CETs). The results showed that there were 3785 genes differentially expressed due to the FP intervention, namely 374 downregulated and 3411 upregulated genes. After analyzing all the differentially expressed genes, two classical KEGG pathways were found to be related to obesity, namely the PPAR-signaling pathway and energy metabolism, involving genes Fabp1–5, Lpl, Gyk, Qqp7, Pparg, Rxrg, Acsl1, Acsl4, Acsl6, Cpt1c, Car1–4, Ca5b, Car8, Car12–14, Cps1, Ndufa4l2, Cox6b2, Atp6v1g2, Ndufa4l2 and Cox4i2. QRT-PCR results showed a consistent expression trend. Our results indicate that FP promotes lipid metabolism by changing the expression of some key genes of CETs, thus inhibiting obesity.

Dietary regulations for microbiota dysbiosis among post-menopausal women with type 2 diabetes

Type 2 diabetes (T2D) and T2D-associated comorbidities, such as obesity, are serious universally prevalent health issues among post-menopausal women. Menopause is an unavoidable condition characterized by the depletion of estrogen, a gonadotropic hormone responsible for secondary sexual characteristics in women. In addition to sexual dimorphism, estrogen also participates in glucose-lipid homeostasis, and estrogen depletion is associated with insulin resistance in the female body. Estrogen level in the gut also regulates the microbiota composition, and even conjugated estrogen is actively metabolized by the estrobolome to maintain insulin levels. Moreover, post-menopausal gut microbiota is different from the pre-menopausal gut microbiota, as it is less diverse and lacks the mucolytic Akkermansia and short-chain fatty acid (SCFA) producers such as Faecalibacterium and Roseburia. Through various metabolites (SCFAs, secondary bile acid, and serotonin), the gut microbiota plays a significant role in regulating glucose homeostasis, oxidative stress, and T2D-associated pro-inflammatory cytokines (IL-1, IL-6). While gut dysbiosis is common among post-menopausal women, dietary interventions such as probiotics, prebiotics, and synbiotics can ease post-menopausal gut dysbiosis. The objective of this review is to understand the relationship between post-menopausal gut dysbiosis and T2D-associated factors. Additionally, the study also provided dietary recommendations to avoid T2D progression among post-menopausal women.

Chemical Composition and Rheological Properties of Seed Mucilages of Various Yellow- and Brown-Seeded Flax (Linum usitatissimum L.) Cultivars

When seeds sown in the soil become wet, their hulls secrete viscous matter that can retain water and thus support germination. Flaxseed mucilage (FSM) is an example of such a material and is attractive for food, cosmetic, and pharmaceutical applications due to its suitable rheological properties. FSM consists mainly of two polysaccharides, namely, arabinoxylan and rhamnogalacturonan I, and it also contains some proteins, minerals, and phenolic compounds. The genotype and the year of the flax harvest can significantly affect the composition and functional properties of FSM. In this work, FSM samples were isolated from flax seeds of different cultivars and harvest years, and their structural and rheological properties were compared using statistical methods. The samples showed significant variability in composition and rheological properties depending on the cultivar and storage time. It was found that the ratio of two polysaccharide fractions and the contribution of less-prevalent proteins are important factors determining the rheological parameters of FSM, characterizing the shear-thinning, thixotropic, and dynamic viscoelastic behavior of this material in aqueous solutions. The yield strength and the hysteresis loop were found to be associated with the contribution of the pectin fraction, which included homogalacturonan and rhamnogalacturonan I. In contrast, the shear-thinning and especially the dynamic viscoelastic properties depended on the arabinoxylan content. Proteins also affected the viscoelastic properties and maintained the elastic component of FSM in the solution. The above structural and rheological characteristics should be taken into account when considering effective applications for this material.

Oleanolic acid reshapes the gut microbiota and alters immune-related gene expression of intestinal epithelial cells

BACKGROUND

Oleanolic acid (OA) is a pentacyclic triterpenoid compound that is present at high levels in olive oil and has several promising pharmacological effects, such as liver protection and anti-inflammatory, antioxidant, and anticancer effects. The purpose of the present study was to assess whether OA treatment affects gut health compared to a control condition, including gut microbiota and intestinal epithelial immunity.

RESULTS

Illumina MiSeq sequencing (16S rRNA gene) was used to investigate the effect of OA on the microbial community of the intestinal tract, while Illumina HiSeq (RNA-seq) technology was used to investigate the regulatory effect of OA on gene expression in intestinal epithelial cells, which allowed for a comprehensive analysis of the effects of OA on intestinal health. The results showed that the consumption of OA initially controlled weight gain in mice and altered the composition of the gut microbiota. At the phylum level, OA significantly increased the relative abundances of cecum Firmicutes but decreased the abundance of Actinobacteria, and at the genus level it increased the relative abundance of potentially beneficial bacteria such as Oscillibacter and Ruminiclostridium 9. Oleanolic acid treatment also altered the expression of 12 genes involved in the Kyoto Encyclopedia of Genes and Genomes（KEGG）pathways of complement and coagulation cascades, hematopoietic cell lineage, and leukocyte transendothelial migration in intestinal epithelial cells to improve gut immunity.

CONCLUSION

Intake of OA can contribute beneficial effects by optimizing gut microbiota and altering the immune function of intestinal epithelial cells, potentially to improve intestinal health status. © 2021 Society of Chemical Industry.

Structure conformation, physicochemical and rheological properties of flaxseed gums extracted under alkaline and acidic conditions

The present work aimed at investigating an extraction protocol based on consecutive steps of isoelectric point (pH ~ 4.25) mediated gum swelling and deproteinisation as an alternative method to produce flaxseed gum extracts of enhanced techno-functional characteristics. The osidic and proximate composition, structure conformation, flow behaviour, dynamic rheological and thermal properties of gums isolated from brown and golden flaxseeds were assessed. Gum extraction under near-to-isoelectric point conditions did not impair the extraction yield, residual protein and ash content, whilst it resulted in minor changes in the sugar composition of the flaxseed gum extracts. The deconvolution of the GPC/SEC chromatographs revealed the presence of four major polysaccharidic populations corresponding to arabinoxylans, rhamnogalacturonan-I and two AX-RG-I composite fractions. The latter appeared to minimise the intra- and interchain polymer non-covalent interactions (hydrogen bonding) leading to a better solvation affinity in water and lyotropic solvents. Golden flaxseed gums exerted higher molecular weight (M_w = 1.34-1.15 × 10⁶ Da) and intrinsic viscosities (6.63-5.13 dL g^-1) as well as better thickening and viscoelastic performance than the brown flaxseed gum exemplars. Golden flaxseed gums exhibited a better thermal stability compared to the brown flaxseed counterparts and therefore, they are suitable for product applications involving severe heat treatments.

Variations in the structural and functional properties of flaxseed gum from six different flaxseed cultivars

Although flaxseed gum (FG) has been widely studied, the differences in its structure and function with respect to various flaxseed cultivars remain unclear. In this study, our objective was to examine the differences between FG samples obtained from different flaxseed cultivars based on their structural and functional properties. Specifically, FG samples from the different cultivars were extracted via hot water extraction followed by ethanol precipitation. Thereafter, they were analyzed via zeta potential measurements, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). The results demonstrated that the different cultivars showed significantly different FG yields (p < .05; range, 5.83%-7.36%). Further, the FTIR spectra of the FG samples were slightly different but showed typical polysaccharide absorption peaks. Furthermore, the XRD patterns obtained predominantly showed an amorphous region and a small crystalline region, while the SEM images obtained at 1,000× magnification revealed that the samples had smooth and irregular surfaces, with a scaly structure. However, at 20,000× magnification, the FG samples showed slight structural differences. Additionally, the zeta potentials of the FG samples (range, -19.4 to -30.6 mV; p < .05) were cultivar-dependent and indicated the presence of negatively charged macromolecules. This implies that the FG samples from the different cultivars show diverse structural properties. Our findings not only provide useful information regarding FG samples extracted from different cultivars but also serve as a theoretical basis for the application of FG in food processing.

Comparisons of the effects of different flaxseed products consumption on lipid profiles, inflammatory cytokines and anthropometric indices in patients with dyslipidemia related diseases: systematic review and a dose-response meta-analysis of randomized controlled trials

BACKGROUND

Flaxseed is widely used as a functional food for its rich sources of linolenic acid, lignans and dietary fibers in the world. This systematic review and dose-response meta-analysis on randomized controlled trials (RCTs) is first to evaluate effects of different flaxseed products (whole flaxseed, oil and lignans) on lipid profiles, inflammatory and anthropometric parameters in patients with dyslipidemia related diseases.

METHODS

Literature search was performed in PubMed, Embase, Cochrane Central, Scopus, and Web of Science from the inception dates to January, 2020. Weighted mean differences with the 95% confidence interval (CI) were pooled using fix or random-effects models.

RESULTS

Thirty-one RCTs involving 1,698 participants were included. The present meta-analysis revealed that flaxseed consumption had an overall beneficial effect on serum TC, LDL-C, TG, apo B and IL-6 in patients with dyslipidemia related diseases, but not on apo A, HDL-C, hs-CRP, CRP and anthropometric indices. However, different flaxseed products showed obviously different effects. Whole flaxseed supplementation significantly reduced TC (- 11.85 mg/dl, 95% CI - 20.12 to - 3.57, P = 0.005), LDL-C (- 10.51 mg/dl, 95% CI - 14.96 to - 6.06, P < 0.001), TG (- 19.77 mg/dl, 95% CI - 33.61 to - 5.94, P = 0.005), apolipoprotein B (- 5.73 mg/dl, 95% CI - 7.53 to - 3.93, P < 0.001), TC/HDL-C (- 0.10, 95% CI - 0.19 to - 0.003, P = 0.044) and weight (- 0.40 kg, 95% CI - 0.76 to - 0.05, P = 0.027); Lignans supplementation significantly reduced TC (- 17.86 mg/dl, P = 0.004), LDL-C (- 15.47 mg/dl, P < 0.001) and TC/HDL-C (- 0.45, P = 0.04). Although flaxseed oil supplementation had no such lowering-effect on lipid, meta-analysis revealed its lowering-effect on IL-6 (- 0.35 pg/ml, P = 0.033) and hs-CRP (- 1.54 mg/l, P = 0.004). Subgroup analysis revealed that whole flaxseed decreased TC, LDL-C and TG levels irrespective of country and the intervention time prescribed, but was more pronounced when the dose of whole flaxseed was ≤ 30 g/day (TC: WMD - 13.61 mg/mL; LDL-C: WMD - 10.52 mg/mL; TG: WMD - 23.52 mg/mL), rather not a dose > 30 g/day. Moreover, a linear relationship between dose of whole flaxseed and absolute changes in C-reactive protein (P = 0.036) and a nonlinear relationship between with IL-6 (P < 0.001) were detected.

CONCLUSIONS

Flaxseed intervention suggested the positive effects on lipid profiles, inflammatory cytokines and anthropometric indices in patients with dyslipidemia related diseases. Of these, whole flaxseed and lignans play an important role in reducing blood lipid, while flaxseed oil mainly plays in anti-inflammatory. Lipid- and weight-lowering was significant when whole flaxseed was consumed at doses < 30 mg/d, for lipid status with mixed dyslipidemia and patients with BMI > 25.

Flaxseed Powder Attenuates Non-Alcoholic Steatohepatitis via Modulation of Gut Microbiota and Bile Acid Metabolism through Gut-Liver Axis

Non-alcoholic steatohepatitis (NASH) is gradually becoming one of the most common and health-endangering diseases; therefore, it is very important to prevent the occurrence of NASH and prevent simple non-alcoholic fatty liver (NAFL) from further developing into NASH. We fed mice a high-fat diet (HFD, 60% fat) for 14 weeks to induce NAFL and then fed different doses of flaxseed powder (low (10%), middle (20%), and high (30%)) to the mice for 28 weeks. After the animal experiment, we analyzed fecal bile acid (BA) profiles of the HFD mice, flaxseed-fed (FLA-fed) mice, and control mice with a normal diet (10% fat) using a targeted metabolomics approach, and we analyzed the gut microbiota at the same time. We also investigated the mechanistic role of BAs in NASH and identified whether the altered BAs strongly bind to colonic FXR or TGR5. In the present study, we found that 28-week FLA treatment notably alleviated NASH development in NAFL model mice fed with an HFD, and the beneficial effects may be attributed to the regulation of and improvement in the gut flora- and microbiota-related BAs, which then activate the intestinal FXR-FGF15 and TGR5-NF-κB pathways. Our data indicate that FLA might be a promising functional food for preventing NASH through regulating microbiomes and BAs.

Could partial nonstarch polysaccharides ameliorate cancer by altering m6A RNA methylation in hosts through intestinal microbiota?

There is a growing scientific view that the improvement of cancer by nonstarch polysaccharides (NSPs) is mediated by intestinal microbiota. Intestinal bacteria affect the supply of methyl donor substances and influence N⁶-methyladenosine (m⁶A) RNA methylation. As one of the epigenetic/epitranscriptomic modifications, m⁶A RNA methylation is closely related to the initiation and progression of cancers. This review summarizes the cancer-improving effects of NSPs through modulation of intestinal microbiota. It also summarizes the relationship between intestinal bacteria and the supply of methyl donor substances. Moreover, it also provides a summary of the effects of m⁶A RNA methylation on various types of cancer. The proposed mechanism is that, dietary consumed NSPs are utilized by specific intestinal bacteria and further reshape the microbial structure. Methyl donor substances will be directly or indirectly generated by the reshaped-microbiota, and affect the m⁶A RNA methylation of cancer-related and pro-carcinogenic inflammatory cytokine genes. Therefore, NSPs may change the m⁶A RNA methylation by affecting the methyl donor supply produced by intestinal microbiota and ameliorate cancer. This review discussed the possibility of cancer improvement of bioactive NSPs achieved by impacting RNA methylation via the intestinal microbiota, and it will offer new insights for the application of NSPs toward specific cancer prevention.

Seed coat mucilages: Structural, functional/bioactive properties, and genetic information

Seed coat mucilages are mainly polysaccharides covering the outer layer of the seeds to facilitate seed hydration and germination, thereby improving seedling emergence and reducing seedling mortality. Four types of polysaccharides are found in mucilages including xylan, pectin, glucomannan, and cellulose. Recently, mucilages from flaxseed, yellow mustard seed, chia seed, and so on, have been used extensively in the areas of food, pharmaceutical, and cosmetics contributing to stability, texture, and appearance. This review, for the first time, addresses the similarities and differences in physicochemical properties, molecular structure, and functional/bioactive properties of mucilages among different sources; highlights their structure and function relationships; and systematically summarizes the related genetic information, aiming with the intent to explore the potential functions thereby extending their future industrial applications.

In vitro fermentation of flaxseed polysaccharide by fecal bacteria inhibits energy intake and adipogenesis at physiological concentration

Obesity and its related metabolic disorders have been a global pandemic. Recently, we found an anti-obesity effect of flaxseed polysaccharide (FP) that could be achieved by regulating intestinal microbiota. The anti-obesity effect of FP is mainly attributed to the metabolites produced by the interaction with FP, which remains to be elucidated. In this research, the in vitro effects of metabolites of FP fermented by fecal bacteria on energy metabolism and adipogenesis were investigated. The effect of energy metabolism was analyzed by mRNA and protein expression of the intestinal glucose transporters, including sodium dependent glucose transporter (SGLT1) and glucose transporter 2 (GLUT2), and glucose uptake in intestinal Caco-2 cells. The lipogenic effect were evaluated by Oil red O staining of intracellular lipid droplets and the mRNA and protein expression of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT-enhancer-binding proteins (C/EBP) α and β in 3T3-L1 cells. The results showed the metabolites significantly inhibited glucose intake through downregulating the mRNA and protein expression of GLUT2 and SGLT1 in Caco-2 cells. Besides, they also led to the decrease of lipid accumulation through downregulating the mRNA and protein expression of PPARγ, C/EBPα, and C/EBPβ in differentiating adipocytes. The inhibitory effects on energy intake and adipogenesis were concentration dependent, and metabolites at physiological concentration showed the most significant effect. Metabolites of fecal bacteria fermenting FP inhibited energy intake and adipogenesis at physiological concentration, which might be one of the weight-loss mechanisms of FP-diet.

Coleus forskohlii and Garcinia indica extracts attenuated lipid accumulation by regulating energy metabolism and modulating gut microbiota in obese mice

Obesity is related to energy imbalance and energy metabolism. In this study, we investigated the anti-obesity effects of Garcinia indica extract (GIE), Coleus forskohlii extract (CFE), and the combinations of these two extracts in a 3T3-L1 cells and high-fat diet (HFD)-induced obese mice. In vitro, GIE showed better effect on TG content than CFE, CFE showed better effect on glycerol released than GIE, and the combinations of GIE and CFE showed both effects compared with GIE and CFE alone. In vivo, GIE, LMIX (0.005% GIE + 0.025% CFE), and HMIX (0.01% GIE + 0.025% CFE) down-regulated adipogenesis-related transcription factors PPARγ and C/EBPα protein expression, CFE promoted lipolysis by up-regulated p-HSL and p-PKA protein expression, and four supplementations promoted fatty acid β-oxidation by up-regulating CPT-1A and PPARα protein expression to decrease lipid accumulation in adipose tissue. Moreover, we found that CFE, LMIX and HMIX, except GIE exert increasing the abundance of Bacteroides caccae compared with HFD group. Overall, GIE, CFE, and the combinations of GIE and CFE were able to decrease body weight and adipocyte size by promoting fatty acid β-oxidation and modulating gut microbiota in HFD-induced obese mice.

Guar gum different from Ganoderma lucidum polysaccharide in alleviating colorectal cancer based on omics analysis

It is unclear if guar gum can alleviate colorectal cancer (CRC). We evaluated the effect of guar gum (unmodified) on the mortality, colon status, serous tumor necrosis factor-alpha (TNF-α) concentration, and gut microbial and colonic epithelial cell gene expression profiles in CRC mice and performed omics analyses to compare these with those of Ganoderma lucidum polysaccharide (GLP), whose main component is β-glucan (>90%). We found that guar gum had a CRC alleviating effect. However, it showed a 20% higher mortality rate, shorter colon length, worse colon status, larger number and size of tumors, higher concentration of serous TNF-α and upregulation of epithelial cell genes (Il10, Cytl1, Igkv7-33, Ighv1-14, Igfbp6 and Foxd3) compared to that of GLP. The higher relative abundance of Akkermansia, the alteration of microbial metabolic pathways, especially those involving chaperones and folding catalysts, fatty acid biosynthesis, glycerophospholipid metabolism, glycolysis/gluconeogenesis, lipid biosynthesis and pyruvate metabolism, and the upregulation of specific genes (Mcpt2, Mcpt9, Des and Sostdc1) were also determined in animals fed a guar gum diet. The results suggested that the alleviating effect of guar gum (an inexpensive polysaccharide) on CRC was inferior to that of GLP (a more expensive polysaccharide). This could potentially be attributed to the increased presence of Akkermansia, the alteration of 10 microbial metabolic pathways and the upregulation of 4 epithelial cell genes.

In Vitro Digestion and Fermentation by Human Fecal Microbiota of Polysaccharides from Flaxseed

The digestion of flaxseed polysaccharides (FSP) in simulated saliva, gastric and small intestine conditions was assessed, as well as in vitro fermentation of FSP by human gut microbiota. FSP was not degraded in the simulated digestive systems (there was no change in molecular weight or content of reducing sugars), indicating that ingested FSP would reach the large intestine intact. Changes in carbohydrate content, reducing sugars and culture pH suggested that FSP could be broken down and used by gut microbiota. FSP modulated the composition and structure of the gut microbiota by altering the Firmicutes/Bacteroidetes ratio and increasing the relative abundances of Prevotella, Phascolarctobacterium, Clostridium and Megamonas, which can degrade polysaccharides. Meanwhile, FSP fermentation increased the concentration of short-chain fatty acids, especially propionic and butyric acids. Our results indicate that FSP might be developed as a functional food that benefits gut health.

Dietary Methionine Restriction Ameliorated Fat Accumulation, Systemic Inflammation, and Increased Energy Metabolism by Altering Gut Microbiota in Middle-Aged Mice Administered Different Fat Diets

Diet greatly influences gut microbiota. Dietary methionine restriction (MR) prevents and ameliorates age-related or high-fat-induced diseases and prolongs life span. This study aimed to reveal the impact of MR on gut microbiota in middle-aged mice with low-, medium-, high-fat diets. C57BL/6J mice were randomly divided into six groups with different MR and fat-content diets. Multiple indicators of intestinal function, fat accumulation, energy consumption, and inflammation were measured. 16S rRNA gene sequencing was used to analyze cecal microbiota. Our results indicated that MR considerably reduced the concentrations of lipopolysaccharide (LPS) and increased short-chain fatty acids (SCFAs) by upregulating the abundance of Corynebacterium and SCFA-producing bacteria Bacteroides, Faecalibaculum, and Roseburia and downregulating the LPS-producing or proinflammatory bacteria Desulfovibrio and Escherichia-Shigella. The effect of MR on LPS and SCFAs further reduced fat accumulation and systemic inflammation, enhanced heat production, and mediated the LPS/LBP/CD14/ TLR4 pathway to strength the intestinal mucosal immunity barrier in middle-aged mice.

Biotransformation of dietary phytoestrogens by gut microbes: A review on bidirectional interaction between phytoestrogen metabolism and gut microbiota

Phytoestrogens are a class of plant produced polyphenolic compounds with diphenolic structure, which is similar to 17β-estradiol. These phytoestrogens preferentially bind to estrogen receptors, however, with weak affinity. Recently, many studies have found that these phytoestrogens can be transformed by gut microbiota through novel enzymatic reactions into metabolites with altered bioactivity. Recent studies have also implied that these metabolites could possibly modulate the host gut ecosystem, gene expression, metabolism and the immune system. Thus, isolating gut microbes capable of biotransforming phytoestrogens and characterizing the novel enzymatic reactions involved are principal to understand the mechanisms of beneficial effects brought by gut microbiota and their metabolism on phytoestrogens, and to provide the theoretical knowledge for the development of functional probiotics. In the present review, we summarized works on gut microbial biotransformation of phytoestrogens, including daidzin (isoflavone), phenylnaringenin (prenylflavonoid), lignans, resveratrol (stilbene) and ellagitannins. We mainly focus on gut bacterial isolation, metabolic pathway characterization, and the bidirectional interaction of phytoestrogens with gut microbes to illustrate the novel metabolic capability of gut microbiota and the methods used in these studies.

Pectin and inulin stimulated the mucus formation at a similar level: An omics-based comparative analysis

Mucin 2 (MUC2) is the skeleton of colonic mucus that comprises the physical intestinal barrier. Different dietary polysaccharides may affect colonic mucus at different extents. The effect of pectin on MUC2 production is contradictory. To investigate whether and how pectin affected hosts' colonic mucus, the amount of MUC2 in colon, the cecal, mucosal microbiota, and metabolites profiles were analyzed and compared with inulin. The results showed pectin stimulated the production of MUC2 at a similar level to inulin. Both interventions increased the abundance of cecal Lachnospira and Christensenellaceae_R-7_group, and enhanced the production of specific metabolites including soyasapogenol B 24-O-b-d-glucoside, lucyoside Q, trans-EKODE-(E)-Ib, and 1,26-dicaffeoylhexacosanediol. Additionally, pectin increased the relative abundance (RA) of cecal Lactobacillus, and induced less RA of potentially harmful bacteria such as Helicobacter in mucosal microbiota than inulin. In conclusion, we first reported that pectin and inulin stimulated the mucus formation at a similar level. Two genera of cecal bacteria and four metabolites may play an important role in enhancing the production of MUC2. Moreover, the MUC2 production may be unrelated to several traditional health-beneficial bacteria; pectin possibly performed as good as or better than the inulin in rats' gut.

Effect of embryo-remaining oat rice on the lipid profile and intestinal microbiota in high-fat diet fed rats

Embryo-remaining oat rice (EROR), as a newly developed oat product, is popular in China for its good taste, but little is known about its healthy functions. In this study, the effects of EROR on lipid metabolism regulation were investigated in in vitro and in vivo models. The results showed that the oat ethanol extracts significantly alleviated lipid accumulation, total cholesterol and triglyceride levels in HepG2 cells. EROR supplementation dramatically improved the lipid profile in the serum and liver and downregulated the expression levels of HMGCR, SREBP-1C and FAS, which are related to lipid metabolic disorder in high-fat diet (HFD) fed rats. A HFD decreases the production of short-chain fatty acids (SCFAs) in the cecum, which are related to intestinal microbiota dysbiosis. The intake of EROR significantly increased the total SCFAs, acetate and propionate and promoted the abundance of SCFA-producing bacteria. Furthermore, the intake of EROR led to abundant increases in Bifidobacterium and Akkermansia and decreases of Rombutsia, Fusicatenibacter, Holdemanella and Turicibacter, which were negatively and positively correlated with the lipid metabolism-related indices. These results provide evidence that EROR is a good functional food candidate to ameliorate lipid metabolic disorder and hyperlipidemia.

Alternating consumption of β-glucan and quercetin reduces mortality in mice with colorectal cancer

The current dietary recommendations for disease prevention and management are scarce and are not well supported. Beta-glucan or quercetin in a diet can alleviate colorectal cancer (CRC) by regulating the gut microbiota and related genes, but the effects of alternating their consumption for routine ingestion during CRC occurrence remain unknown. This study investigated the effects of alternating the consumption of β-glucan and quercetin for routine ingestion on CRC development in mice. The mortality rate, colonic length, inflammatory cytokines, gut microbiota, and colonic epithelial gene expression in healthy and CRC mice that consumed normal and alternate diets were compared and studied. The results showed that alternating the consumption of β-glucan and quercetin (alternating among a β-glucan diet, a normal diet and a normal diet that was supplemented with quercetin) alleviated colon damage and reduced the mortality rate in CRC mice, with a reduction in mortality of 12.5%. Alternating the consumption of β-glucan and quercetin significantly decreased the TNF-α level, increased the relative abundance of Parabacteroides, and downregulated three genes (Hmgcs2, Fabp2, and Gpt) that are associated with inflammation and cancer. Alternating the consumption of some bioactive compounds, such as β-glucan and quercetin, in food can contribute to human health. This experiment provided some experimental evidence for the dietary recommendations for disease prevention and management.

Antiobesity Effect of Flaxseed Polysaccharide via Inducing Satiety due to Leptin Resistance Removal and Promoting Lipid Metabolism through the AMP-Activated Protein Kinase (AMPK) Signaling Pathway

Obesity is a metabolic syndrome worldwide that causes many chronic diseases. Recently, we found an antiobesity effect of flaxseed polysaccharide (FP), but the mechanism remains to be elucidated. In this study, rats were first induced to develop obesity by being fed a high-fat diet. The obese rats were then fed a control diet, AIN-93M (group HFD), or a 10% FP diet (group FPD). The body weight, body fat, adipose tissue and liver sections, serous total triglycerides, levels of fasting blood glucose in serum, serous insulin, inflammatory cytokines in serum, and serous proteins within the leptin-neuropeptide Y (NPY) and AMP-activated protein kinase (AMPK) signaling pathway were determined and analyzed. FP intervention significantly reduced body weight and abdominal fat from 530 ± 16 g and 2.15% ± 0.30% in group HFD to 478 ± 10 g and 1.38% ± 0.48% in group FPD, respectively. This effect was achieved by removing leptin resistance possibly by inhibiting inflammation and recovering satiety through the significant downregulation of NPY and the upregulation of glucagon-like peptide 1. Adiponectin was then significantly upregulated probably via the gut-brain axis and further activated the AMPK signaling pathway to improve lipid metabolism including the improvement of lipolysis and fatty acid oxidation and the suppression of lipogenesis. This is the first report of the proposed antiobesity mechanism of FP, thereby providing a comprehensive understanding of nonstarch polysaccharides and obesity.

The Alternate Consumption of Quercetin and Alliin in the Traditional Asian Diet Reshaped Microbiota and Altered Gene Expression of Colonic Epithelial Cells in Rats

The diet of traditional Asian is similar to the Mediterranean that was considered as a healthy dietary pattern. The report was scarce on whether different plant-derived components with similar anti-oxidative and anti-inflammatory function such as quercetin and alliin in traditional Asian diet consumed in an alternate style cooperatively affect health including the growth of host and the status of the gut microbiota and colonic epithelial immunity. In the present study, the effects of alternate consumption of quercetin and alliin on host health judging by the profile of gut microbiota and gene expression of colonic epithelial cells were investigated with the Illumina MiSeq sequencing (16S rRNA genes) and Illumina HiSeq (RNA-seq) technique, respectively. The results showed that the alternate consumption significantly increased the rat body weight and reshaped the gut microbiota composition. At the phylum level, it significantly increased the relative abundance of fecal Firmicutes and Cyanobacteria but decreased that of Bacteroidetes (P < 0.05) and increased the relative abundance of Candidatus Arthromitus, Lactococcus, Geobacillus, and Ruminococcus at the genus level that benefits the host's health. The alternate consumption of quercetin and alliin also altered 13 genes expression involved in the KEGG pathways of complement and coagulation cascades and hematopoietic cell lineage to improve the gut immunity. Therefore, the alternate consumption of quercetin and alliin in traditional Asian diet can contribute beneficial metabolic effects by optimizing gut microbiota and altering the immunologic function of colonic epithelial cells, resulting in its potential to improve the sub-health status.

Ganoderma lucidum polysaccharide improves rat DSS-induced colitis by altering cecal microbiota and gene expression of colonic epithelial cells

Background

The effects of β-glucan on colitis mice are contradictory in previous reports. As a result, it is still unclear whether there is an anti-colitis effect in Ganoderma lucidum polysaccharide (GLP), which is mainly composed of β-glucan. Moreover, the association between GLP function and gut microbiota remains to be elucidated.

Objective

This study aimed to investigate whether GLP consumption improved rat dextran sodium sulfate (DSS)-induced colitis by regulating gut microbiota and altering colonic epithelial expression.

Design

The disease activity index (DAI) scores and the cecal short chain fatty acid (SCFA) levels of DSS-induced colitis rats fed with a GLP diet (Group GLP, n = 6) and a control diet (Group Con, n = 6) were investigated and analyzed. Moreover, the profiles of gut microbiota and colonic epithelial expression were analyzed using metagenomics and transcriptomics.

Results

GLP consumption significantly lowered animal DAI scores by producing more SCFAs by increasing SCFA-producing bacteria such as Ruminococcus_1 and reducing pathogens such as Escherichia-Shigella in both the small intestine and cecum of rat. Moreover, GLP consumption regulated 11 genes, including six upregulated (Ccl5, Cd3e, Cd8a, Il21r, Lck, and Trbv) and five downregulated (Ccl3, Gro, Il11, Mhc2, and Ptgs) genes enriched in six inflammation-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, resulting in enhancement of immunity and reduction of inflammatory response and colonic cancer risk.

Conclusions

GLP consumption alleviated DSS-induced colitis and may have potential for ulcerative colitis relief.

Bioprocessing of Functional Ingredients from Flaxseed

Flaxseeds (Linum usitatissimum L.) are oilseeds endowed with nutritional constituents such as lignans, lipids, proteins, fibre, carbohydrates, and micronutrients. Owing to their established high nutritional profile, flaxseeds have gained an established reputation as a dietary source of high value functional ingredients. Through the application of varied bioprocessing techniques, these essential constituents in flaxseeds can be made bioavailable for different applications such as nutraceuticals, cosmetics, and food industry. However, despite their food and health applications, flaxseeds contain high levels of phytotoxic compounds such as linatine, phytic acids, protease inhibitors, and cyanogenic glycosides. Epidemiological studies have shown that the consumption of these compounds can lead to poor bioavailability of essential nutrients and/or health complications. As such, these components must be removed or inactivated to physiologically undetectable limits to render flaxseeds safe for consumption. Herein, critical description of the types, characteristics, and bioprocessing of functional ingredients in flaxseed is presented.