Effects of short-term fructooligosaccharide intake on equol production in Japanese postmenopausal women consuming soy isoflavone supplements: a pilot study

The effects of quinoa bran dietary fiber on glucose and lipid metabolism and hepatic transcriptome in obese rats

BACKGROUND

As a complex chronic metabolic disease, obesity not only affects the quality of human life but also increases the risk of various other diseases. Therefore, it is important to investigate the molecular mechanisms and therapeutic effects of dietary interventions that counteract obesity.

RESULTS

In this study, we extracted soluble (SDF) and insoluble dietary fiber (IDF) from quinoa bran using an enzymatic method and further investigated their effects on lipid metabolism and blood lipid levels in obese rats. Quinoa bran dietary fiber showed significantly reduced body weight, blood glucose level, total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels compared to those in the model group of obese rats. Aspartate aminotransferase and alanine aminotransferase levels were significantly lower in the IDF group, demonstrating that IDF improved liver injury more significantly than SDF, which was consistent with the analysis of liver tissue sections. IDF supplementation significantly improved the oxidation resistance of obese rats by decreasing malondialdehyde and increasing superoxide dismutase and glutathione peroxidase levels compared to the high-fat diet group levels. Transcriptome analysis showed that IDF caused hepatic changes in genes (Ehhadh, PPARα, FADS, CPT1, CPT2, SCD-1, Acadm, and CYP7A1) related to fatty acid degradation, and this result coincided with that of the gene expression validation result.

CONCLUSION

Overall, our research offers crucial data for the logical development of dietary fiber from quinoa bran with nutritional purposes. © 2023 Society of Chemical Industry.

Soy isoflavone-specific biotransformation product S-equol in the colon: physiological functions, transformation mechanisms, and metabolic regulatory pathways

Epidemiological data suggest that regular intake of soy isoflavones may reduce the incidence of estrogen-dependent and aging-associated disorders. Equol is a metabolite of soy isoflavone (SI) produced by specific gut microbiota and has many beneficial effects on human health due to its higher biological activity compared to SI. However, only 1/3 to 1/2 of humans are able to produce equol in the body, which means that not many people can fully benefit from SI. This review summarizes the recent advances in equol research, focusing on the chemical properties, physiological functions, conversion mechanisms in vitro and vivo, and metabolic regulatory pathways affecting S-equol production. Advanced experimental designs and possible techniques in future research plan are also fully discussed. Furthermore, this review provides a fundamental basis for researchers in the field to understand individual differences in S-equol production, the efficiency of metabolic conversion of S-equol, and fermentation production of S-equol in vitro.

Fecal microbiota transplantation as a promising treatment option for osteoporosis

Osteoporosis is a systemic metabolic bone disease characterized by the descending bone mass and destruction of bone microstructure, which tends to result in the increased bone fragility and associated fractures, as well as high disability rate and mortality. The relation between gut microbiota and bone metabolism has gradually become a research hotspot, and it has been verified that gut microbiota is closely associated with reduction of bone mass and incidence of osteoporosis recently. As a novel "organ transplantation" technique, fecal microbiota transplantation (FMT) mainly refers to the transplantation of gut microbiota from healthy donors to recipients with gut microbiota imbalance, so that the gut microbiota in recipients can be reshaped and play a normal function, and further prevent or treat the diseases related to gut microbiota disorder. Herein, based on the gut-bone axis and proven regulatory effects of gut microbiota on osteoporosis, this review expounds relevant basic researches and clinical practice of FMT on osteoporosis, thus demonstrating the potentials of FMT as a therapeutic option for osteoporosis and further providing certain reference for the future researches.

Therapeutic Potential of Isoflavones with an Emphasis on Daidzein

Daidzein is a phytoestrogen isoflavone found in soybeans and other legumes. The chemical composition of daidzein is analogous to mammalian estrogens, and it could be useful with a dual-directional purpose by substituting/hindering with estrogen and estrogen receptor (ER) complex. Hence, daidzein puts forth shielding effects against a great number of diseases, especially those associated with the control of estrogen, such as breast cancer, diabetes, osteoporosis, and cardiovascular disease. However, daidzein also has other ER-independent biological activities, such as oxidative damage reduction acting as an antioxidant, immune regulator as an anti-inflammatory agent, and apoptosis regulation, directly linked to its potential anticancer effects. In this sense, the present review is aimed at providing a deepen analysis of daidzein pharmacodynamics and its implications in human health, from its best-known effects alleviating postmenopausal symptoms to its potential anticancer and antiaging properties.

Effects of supplementing sow diets during late gestation with Pennisetum purpureum on antioxidant indices, immune parameters and faecal microbiota

The purpose of this study was to investigate the effects of adding Pennisetum purpureum (P. purpureum, also known as Napier grass or elephant grass) to the diets of late gestation on the antioxidant indexes, immune indexes and faecal microbiota of sows. At the 90 days of gestation, 300 healthy sows were randomly divided into three groups, and they received the basic commercial diet or added 5% P. purpureum and 10% P. purpureum, respectively. The experiment started from 90 days of gestation to parturition. The results showed that the total antioxidant capacity, immunoglobulins and serum equol concentrations of sows on 100 days of gestation and at parturition increased linearly (p < .05) with the increase of the content of P. purpureum in the gestation diet. The 5% P. purpureum increased the relative abundance of Bacteroidetes (p = .027) and Actinobacteria (p < .001) at phylum level, Coriobacteriaceae (p < .001) at family level and Prevotellaceae_UCG_001 (p = .004) at genus level, and decreased the relative abundance of Escherichia_Shigella (p < .001) at genus level. In summary, this study shows that the additive of P. purpureum can increase the concentration of serum equol, improve the antioxidant capacity and immune function of sow in late gestation. In addition, the additive of 5% P. purpureum in the diet might change the composition of intestinal microbiota of sows, particularly the relative abundance of Coriobacteriaceae (p < .001) increased.

Effects of psyllium seed husk powder, methylcellulose, pregelatinised starch, and cold water swelling starch on the production of gluten free crackers

Psyllium seed husk powder and pregelatinised starch crackers had comparable textural properties and sound release to wheat crackers, while the functionality of methylcellulose was limited due to low moisture addition.

Insight into Polyphenol and Gut Microbiota Crosstalk: Are Their Metabolites the Key to Understand Protective Effects against Metabolic Disorders?

Lifestyle factors, especially diet and nutrition, are currently regarded as essential avenues to decrease modern-day cardiometabolic disorders (CMD), including obesity, metabolic syndrome, type 2 diabetes, and atherosclerosis. Many groups around the world attribute these trends, at least partially, to bioactive plant polyphenols given their anti-oxidant and anti-inflammatory actions. In fact, polyphenols can prevent or reverse the progression of disease processes through many distinct mechanisms. In particular, the crosstalk between polyphenols and gut microbiota, recently unveiled thanks to DNA-based tools and next generation sequencing, unravelled the central regulatory role of dietary polyphenols and their intestinal micro-ecology metabolites on the host energy metabolism and related illnesses. The objectives of this review are to: (1) provide an understanding of classification, structure, and bioavailability of dietary polyphenols; (2) underline their metabolism by gut microbiota; (3) highlight their prebiotic effects on microflora; (4) discuss the multifaceted roles of their metabolites in CMD while shedding light on the mechanisms of action; and (5) underscore their ability to initiate host epigenetic regulation. In sum, the review clearly documents whether dietary polyphenols and micro-ecology favorably interact to promote multiple physiological functions on human organism.

Systematic review of the effects of the intestinal microbiota on selected nutrients and non-nutrients

PURPOSE

There is considerable interest in the effects of the intestinal microbiota (IM) composition, its activities in relation with the metabolism of dietary substrates and the impact these effects may have in the development and prevention of certain non-communicable diseases. It is acknowledged that a complex interdependence exists between the IM and the mammalian host and that the IM possesses a far greater diversity of genes and repertoire of metabolic and enzymatic capabilities than their hosts. However, full knowledge of the metabolic activities and interactions of the IM and the functional redundancy that may exist are lacking. Thus, the current review aims to assess recent literature relating to the role played by the IM in the absorption and metabolism of key nutrients and non-nutrients.

METHODS

A systematic review (PROSPERO registration: CRD42015019087) was carried out focussing on energy and the following candidate dietary substrates: protein, carbohydrate, fat, fibre, resistant starch (RS), and polyphenols to further understand the effect of the IM on the dietary substrates and the resulting by-products and host impacts. Particular attention was paid to the characterisation of the IM which are predominantly implicated in each case, changes in metabolites, and indirect markers and any potential impacts on the host.

RESULTS

Studies show that the IM plays a key role in the metabolism of the substrates studied. However, with the exception of studies focusing on fibre and polyphenols, there have been relatively few recent human studies specifically evaluating microbial metabolism. In addition, comparison of the effects of the IM across studies was difficult due to lack of specific analysis/description of the bacteria involved. Considerable animal-derived data exist, but experience suggests that care must be taken when extrapolating these results to humans. Nevertheless, it appears that the IM plays a role in energy homeostasis and that protein microbial breakdown and fermentation produced ammonia, amines, phenols and branch chain fatty acids, and a greater diversity in the microbes present. Few recent studies appear to have evaluated the effect of the IM composition and metabolism per se in relation with digestible dietary carbohydrate or fat in humans. Intakes of RS and prebiotics altered levels of specific taxa that selectively metabolised specific prebiotic/carbohydrate-type substances and levels of bifidobacteria and lactobacilli were observed to increase. In controlled human studies, consistent data exist that show a correlation between the intake of fibre and an increase in bifidobacteria and short-chain fatty acids, in particular butyrate, which leads to lower intestinal pH. Dietary polyphenols rely on modification either by host digestive enzymes or those derived from the IM for absorption to occur. In the polyphenol-related studies, a large amount of inter-individual variation was observed in the microbial metabolism and absorption of certain polyphenols.

CONCLUSIONS

The systematic review demonstrates that the IM plays a major role in the breakdown and transformation of the dietary substrates examined. However, recent human data are limited with the exception of data from studies examining fibres and polyphenols. Results observed in relation with dietary substrates were not always consistent or coherent across studies and methodological limitations and differences in IM analyses made comparisons difficult. Moreover, non-digestible components likely to reach the colon are often not well defined or characterised in studies making comparisons between studies difficult if not impossible. Going forward, further rigorously controlled randomised human trials with well-defined dietary substrates and utilizing omic-based technologies to characterise and measure the IM and their functional activities will advance the field. Current evidence suggests that more detailed knowledge of the metabolic activities and interactions of the IM hold considerable promise in relation with host health.

Equol, a Dietary Daidzein Gut Metabolite Attenuates Microglial Activation and Potentiates Neuroprotection In Vitro

Estrogen deficiency has been well characterized in inflammatory disorders including neuroinflammation. Daidzein, a dietary alternative phytoestrogen found in soy (Glycine max) as primary isoflavones, possess anti-inflammatory activity, but the effect of its active metabolite Equol (7-hydroxy-3-(4′-hydroxyphenyl)-chroman) has not been well established. In this study, we investigated the anti-neuroinflammatory and neuroprotective effect of Equol in vitro. To evaluate the potential effects of Equol, three major types of central nervous system (CNS) cells, including microglia (BV-2), astrocytes (C6), and neurons (N2a), were used. Effects of Equol on the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), Mitogen activated protein kinase (MAPK) signaling proteins, and apoptosis-related proteins were measured by western blot analysis. Equol inhibited the lipopolysaccharide (LPS)-induced TLR4 activation, MAPK activation, NF-kB-mediated transcription of inflammatory mediators, production of nitric oxide (NO), release of prostaglandin E2 (PGE-2), secretion of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), in Lipopolysaccharide (LPS)-activated murine microglia cells. Additionally, Equol protects neurons from neuroinflammatory injury mediated by LPS-activated microglia through downregulation of neuronal apoptosis, increased neurite outgrowth in N2a cell and neurotrophins like nerve growth factor (NGF) production through astrocytes further supporting its neuroprotective potential. These findings provide novel insight into the anti-neuroinflammatory effects of Equol on microglial cells, which may have clinical significance in cases of neurodegeneration.

Maternal Prebiotic Ingestion Increased the Number of Fecal Bifidobacteria in Pregnant Women but Not in Their Neonates Aged One Month

Fructooligosaccharides (FOS) can selectively stimulate the growth of bifidobacteria. Here, we investigated the effect of maternal FOS ingestion on maternal and neonatal gut bifidobacteria. In a randomized, double-blind, placebo-controlled study, we administered 8 g/day of FOS or sucrose to 84 women from the 26th week of gestation to one month after delivery. The bifidobacteria count was detected using quantitative PCR in maternal (26 and 36 weeks of gestation) and neonatal (one month after delivery) stools. Maternal stool frequency was recorded from 24 to 36 weeks of gestation. The number of fecal Bifidobacterium spp. and Bifidobacterium longum in the FOS group was significantly higher than that in the placebo group at 36 weeks of gestation (2.7 × 10¹⁰/g vs. 1.1 × 10¹⁰/g and 2.3 × 10¹⁰/g vs. 9.7 × 10⁹/g). In their neonates, these numbers did not differ between the groups. Also, stool frequency in the FOS group was slightly higher than that in the placebo group two weeks after the intervention (1.0 vs. 0.8 times/day), suggesting a potential constipation alleviation effect. In conclusion, the maternal FOS ingestion showed a bifidogenic effect in pregnant women but not in their neonates.

The combined effects of soya isoflavones and resistant starch on equol production and trabecular bone loss in ovariectomised mice

Equol is a metabolite of the soya isoflavone (ISO) daidzein that is produced by intestinal microbiota. Equol has greater oestrogenic activity compared with other ISO, and it prevents bone loss in postmenopausal women. Resistant starch (RS), which has a prebiotic activity and is a dietary fibre, was reported to promote equol production. Conversely, the intestinal microbiota is reported to directly regulate bone health by reducing inflammatory cytokine levels and T-lymphocytes in bone. The present study evaluated the combined effects of diet supplemented with ISO and RS on intestinal microbiota, equol production, bone mineral density (BMD) and inflammatory gene expression in the bone marrow of ovariectomised (OVX) mice. Female ddY strain mice, aged 8 weeks, were either sham-operated (Sham, n 7) or OVX. OVX mice were randomly divided into the following four groups (seven per group): OVX control (OVX); OVX fed 0·05 % ISO diet (OVX+ISO); OVX fed 9 % RS diet (OVX+RS); and OVX fed 0·05 % ISO- and 9 % RS diet (OVX+ISO+RS). After 6 weeks, treatment with the combination of ISO and RS increased equol production, prevented the OVX-induced decline in trabecular BMD in the distal femur by modulating the enteric environment and altered OVX-induced inflammation-related gene expression in the bone marrow. However, there were no significant differences in bone parameters between the ISO+RS and ISO-alone groups in OVX mice. Our findings suggest that the combination of ISO and RS might alter intestinal microbiota and immune status in the bone marrow, resulting in attenuated bone resorption in OVX mice.

Phytoestrogen consumption and risk for cognitive decline and dementia: With consideration of thyroid status and other possible mediators

It is predicted that around 20% of the worlds population will be age 60 or above by 2050. Prevalence of cognitive decline and dementia is high in older adults and modifiable dietary factors may be able to reduce risk for these conditions. Phytoestrogens are bioactive plant chemicals found in soy, which have a similarity in structure to natural estradiol (the most abundant circulating estrogen). This structural likeness enables phytoestrogens to interact with estrogen receptors in the brain, potentially affecting cognition. However, findings in this domain are largely inconsistent, with approximately 50% of studies showing positive effects of phytoestrogens on cognition and the other half resulting in null/negative findings. This paper provides an updated review of the relationship between consumption of phytoestrogens and risk for cognitive decline and/or dementia. In particular, possible mediators were identified to explain discrepant findings and for consideration in future research. A case can be made for a link between phytoestrogen consumption, thyroid status and cognition in older age, although current findings in this area are very limited. Evidence suggests that inter-individual variants that can affect phytoestrogen bioavailability (and thus cognitive outcome) include age and ability to breakdown ingested phytoestrogens into their bioactive metabolites. Factors of the study design that must be taken into account are type of soy product, dosage, frequency of dietary intake and type of cognitive test used. Guidelines regarding optimal phytoestrogen dosage and frequency of intake are yet to be determined.

Could the gut microbiota reconcile the oral bioavailability conundrum of traditional herbs?

ETHNOPHARMACOLOGICAL RELEVANCE

A wealth of information is emerging about the impact of gut microbiota on human health and diseases such as cardiovascular diseases, obesity and diabetes. As we learn more, we find out the gut microbiota has the potential as new territory for drug targeting. Some novel therapeutic approaches could be developed through reshaping the commensal microbial structure using combinations of different agents. The gut microbiota also affects drug metabolism, directly and indirectly, particularly towards the orally administered drugs. Herbal products have become the basis of traditional medicines such as traditional Chinese medicine and also been being considered valuable materials in modern drug discovery. Of note, low oral bioavailability but high bioactivity is a conundrum not yet solved for some herbs. Since most of herbal products are orally administered, the herbs' constituents are inevitably exposed to the intestinal microbiota and the interplays between herbal constituents and gut microbiota are expected. Emerging explorations of herb-microbiota interactions have an opportunity to revolutionize the way we view herbal therapeutics. The present review aims to provide information regarding the health promotion and/or disease prevention by the interplay between traditional herbs with low bioavailability and gut microbiota through gut microbiota via two different types of mechanisms: (1) influencing the composition of gut microbiota by herbs and (2) metabolic reactions of herbal constituents by gut microbiota.

MATERIALS AND METHODS

The major data bases (PubMed and Web of Science) were searched using "gut microbiota", "intestinal microbiota", "gut flora", "intestinal flora", "gut microflora", "intestinal microflora", "herb", "Chinese medicine", "traditional medicine", or "herbal medicine" as keywords to find out studies regarding herb-microbiota interactions. The Chinese Pharmacopoeia (2010 edition, Volume I) was also used to collect the data of commonly used medicinal herbs and their quality control approaches.

RESULTS

Among the 474 monographs of herbs usually used in the Chinese Pharmacopoeia, the quality control approach of 284 monographs is recommended to use high-performance liquid chromatography approach. Notably, the major marker compounds (>60%) for quality control are polyphenols, polysaccharides and saponins, with significant oral bioavailability conundrum. Results from preclinical and clinical studies on herb-microbiota interactions showed that traditional herbs could exert heath promotion and disease prevention roles via influencing the gut microbiota structure. On the other hand, herb constituents such as ginsenoside C-K, hesperidin, baicalin, daidzin and glycyrrhizin could exert their therapeutic effects through gut microbiota-mediated bioconversion.

CONCLUSIONS

Herb-microbiota interaction studies provide novel mechanistic understanding of the traditional herbs that exhibit poor oral bioavailability. "Microbiota availability" could be taken consideration into describing biological measurements in the therapeutic assessment of herbal medicine. Our review should be of value in stimulating discussions among the scientific community on this relevant theme and prompting more efforts to complement herb-microbiota interactions studies.