Influence of inulin on plasma isoflavone concentrations in healthy postmenopausal women

Pomegranate Juice Supplemented with Inulin Modulates Gut Microbiota and Promotes the Production of Microbiota-Associated Metabolites in Overweight/Obese Individuals: A Randomized, Double-Blind, Placebo-Controlled Trial

Pomegranate juice (PJ) and inulin have been reported to ameliorate diet-induced metabolic disorders by regulating gut microbiota dysbiosis. However, there was a lack of clinical evidence for the combined effects of PJ and inulin on regulating gut microbiota in individuals with metabolic disorders. A double-blind, parallel, randomized, placebo-controlled trial was conducted, and 68 overweight/obese individuals (25 ≤ BMI ≤ 35 kg/m2) were randomly assigned to receive 200 mL/d PJ, PJ supplemented with inulin, or placebo for 3 weeks. Our results showed that PJ and PJ+inulin did not significantly alter the levels of anthropometric and blood biochemical indicators after 3 weeks of treatment. However, there was an increasingly significant impact from placebo to PJ to PJ+inulin on the composition of gut microbiota. Detailed bacterial abundance analysis further showed that PJ+inulin treatment more profoundly resulted in significant changes in the abundance of gut microbiota at each taxonomic level than PJ. Moreover, PJ+inulin treatment also promoted the production of microbiota-associated short-chain fatty acids and pomegranate polyphenol metabolites, which correlated with the abundance of the bacterial genus. Our results suggested that PJ supplemented with inulin modulates gut microbiota composition and thus promotes the production of microbiota-associated metabolites that exert potential beneficial effects in overweight/obese subjects.

Sex-specific pharmacokinetic response to phytoestrogens in Drosophila melanogaster

Drosophila melanogaster, or the fruit fly, is widely used for modeling numerous human diseases, such as neurodegeneration, tumor development, cachexia, and intestinal dysfunction. It is a suitable model organism for research targeting the physiology and pathophysiology of the intestinal epithelial barrier and has also been used as a model organism for preliminary drug and bioactive nutrient screening. However, the application of D. melanogaster in research on drug bioavailability and pharmacokinetic properties has not yet been well explored. In this study, we applied D. melanogaster to investigate the absorption and excretion of the orally administered phytoestrogens daidzein, glycitein, genistein, and their glycosides. Therefore, we established a quick, noninvasive method to quantify compound retention in D. melanogaster, suitable for the investigation of a broad variety of potentially bioactive substances. We showed that fruit fly sex plays a key role in the metabolization, transportation, and excretion of phytoestrogenic isoflavones. In particular, female fruit flies retained significantly more isoflavones than male fruit flies, which was reflected in the greater metabolic impact of isoflavones on females. Male fruit flies excreted more isoflavones than females did, which was linked to the upregulation of the xenobiotic transporter gene Mdr50. We also demonstrated that micellized isoflavones were more bioavailable than powdered isoflavones, independent of sex, age or the addition of dietary fibers.

The Influence of Soy Isoflavones and Soy Isoflavones with Inulin on Kidney Morphology, Fatty Acids, and Associated Parameters in Rats with and without Induced Diabetes Type 2

Diabetes mellitus resulting from hyperglycemia stands as the primary cause of diabetic kidney disease. Emerging evidence suggests that plasma concentrations of soy isoflavones, substances with well-established antidiabetic properties, rise following supplemental inulin administration. The investigation encompassed 36 male Sprague-Dawley (SD) rats segregated into two cohorts: non-diabetic and diabetic, induced with type 2 diabetes (high-fat diet + two intraperitoneal streptozotocin injections). Each cohort was further divided into three subgroups (n = 6): control, isoflavone-treated, and isoflavone plus inulin-treated rats. Tail blood glucose and ketone levels were gauged. Upon termination, blood samples were drawn directly from the heart for urea, creatinine, and HbA1c/HbF analyses. One kidney per rat underwent histological (H-E) and immunohistochemical assessments (anti-AQP1, anti-AQP2, anti-AVPR2, anti-SLC22A2, anti-ACC-alpha, anti-SREBP-1). The remaining kidney underwent fatty acid methyl ester analysis. Results unveiled notable alterations in water intake, body and kidney mass, kidney morphology, fatty acids, AQP2, AVPR2, AcetylCoA, SREBP-1, blood urea, creatinine, and glucose levels in control rats with induced type 2 diabetes. Isoflavone supplementation exhibited favorable effects on plasma urea, plasma urea/creatinine ratio, glycemia, water intake, and kidney mass, morphology, and function in type 2 diabetic rats. Additional inulin supplementation frequently modulated the action of soy isoflavones.

Evaluation of Olive Leaf Phenolic Compounds' Gastrointestinal Stability Based on Co-Administration and Microencapsulation with Non-Digestible Carbohydrates

The large generation of olive by-products has motivated their revalorization into high-added-value products. In this regard, olive leaves pose as an interesting source of bioactive compounds, due to their phenolic content with commonly known antioxidant, anti-inflammatory, and immunomodulatory properties, with potential application in non-communicable diseases. However, their effectiveness and applicability into functional foods is limited by their instability under gastrointestinal conditions. Thus, the development of protective formulations is essential. In this study, the spray-drying encapsulation of a phenolic-rich olive leaf extract with inulin as the encapsulating agent was optimized. Then, the behavior of the free extract under gastrointestinal conditions, its co-administration with the encapsulating agent, and the optimized microencapsulated formulation were studied through an in vitro gastrointestinal digestion process following the INFOGEST protocol. Digestion of the free extract resulted in the degradation of most compounds, whereas this was minimized in the co-administration of the non-encapsulated extract with the encapsulating agent. This protective effect, related to its interaction with inulin, was similar to the microencapsulated formulation. Thus, both approaches, co-administration and microencapsulation with inulin, could be promising strategies for the improvement of the stability of these anti-inflammatory and immunomodulatory compounds under gastrointestinal conditions, enhancing their beneficial effect.

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 Lipid-Based Encapsulation on the Bioaccessibility and Bioavailability of Phenolic Compounds

Phenolic compounds (quercetin, rutin, cyanidin, tangeretin, hesperetin, curcumin, resveratrol, etc.) are known to have health-promoting effects and they are accepted as one of the main proposed nutraceutical group. However, their application is limited owing to the problems related with their stability and water solubility as well as their low bioaccessibility and bioavailability. These limitations can be overcome by encapsulating phenolic compounds by physical, physicochemical and chemical encapsulation techniques. This review focuses on the effects of encapsulation, especially lipid-based techniques (emulsion/nanoemulsion, solid lipid nanoparticles, liposomes/nanoliposomes, etc.), on the digestibility characteristics of phenolic compounds in terms of bioaccessibility and bioavailability.

Impact of prebiotics on equol production from soymilk isoflavones by two Bifidobacterium species

The influence of commercial prebiotics (fructo-oligosaccharides and inulin) and sugars (glucose and sucrose) on enhancing equol production from soymilk isoflavones by Bifidobacterium longum BB536 and Bifidobacterium breve ATCC 15700 was evaluated in vitro. Sterilized soymilk was inoculated with each bacterial species at 37 °C for 48 h. The growth and β-glucosidase enzyme activity for the two Bifidobacterium species in soymilk throughout fermentation were assessed. The highest viable count for B. breve (8.75 log CFU/ml) was reached at 36 h and for B. longum (8.55 log CFU/ml) at 24 h. Both bacterial species displayed β-glucosidase activity. B. breve showed increased enzyme activity (4.126 U) at 36 h, while B. longum exhibited maximum activity (3.935 U) at 24 h of fermentation. Among the prebiotics screened for their effect in isoflavones transformation to equol, inulin delivered the highest effect on equol production. The co-culture of B. longum BB536 and B. breve ATCC15700 in soymilk supplemented with inulin produced the highest level (11.49 mmol/l) of equol at 48 h of fermentation process. Level of daidzin declined whereas that of daidzein increased, and then gradually decreased due to formation of equol when soymilk was fermented using bifidobacterial. This suggests that the nutritional value of soymilk may be increased by increasing bioavailability of the bioactive ingredients. Collectively these data identify probiotics and prebiotic combinations suitable for inclusion in soymilk to enhance equol production.

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.

Red clover isoflavone metabolite bioavailability is decreased after fructooligosaccharide supplementation

BACKGROUND

Red clover is an important source of isoflavones; which has been made commercially available as dietary supplements for the treatment of menopausal symptoms. Bioavailability and metabolism of these red clover isoflavones (RCI) have not been studied in detail. Fructooligosaccharides (FOS) stimulate the growth of intestinal bacteria and play an important role in the formation of certain isoflavone metabolites, such as equol and O-desmethylangolensin.

OBJECTIVE

To determine the bioavailability of RCI metabolites and analyse whether FOS supplementation could influence their bioavailability.

METHODS

Seventeen healthy adults were enrolled in the study carried out in two periods. In the first, compound bioavailability was determined after consumption of 80 mg of RCI (MF11RCE). In the second, a 6-day supplementation of 2×3000 mg/day of FOS was administered before isoflavone consumption.

RESULTS

Biochanin A and formononetin were rapidly absorbed and both reached maximum concentrations at an average of 5-7h. Demethylation was a major reaction in the metabolic pathway. Daidzein serum level peaked after about 12.6h. Supplementation with FOS led to a significant decrease in the bioavailability of daidzein, dihydroformononetin, dihydrogenistein and dihydrodaidzein. An increase in equol production was also observed which did not reach statistical significance (p>0.05).

CONCLUSION

This study is the first to provide detailed data on RCI bioavailability in humans and determine no influence of FOS yet a trend toward increased equol production. More research is warranted involving a greater sample size.

Effects of the Chinese Herbal Formulation (Liu Wei Di Huang Wan) on the Pharmacokinetics of Isoflavones in Postmenopausal Women

A combination of soy isoflavones and Liu Wei Di Huang Wan (LWDHW) is potentially effective for postmenopausal women with intolerable vasomotor episodes who are not suitable candidates for hormonal therapy. The objective of this open-label, three-phase, crossover study was to determine the influence of both single and multiple oral doses of LWDHW on isoflavone pharmacokinetics in healthy postmenopausal women. Eleven subjects were assigned to receive the following regimens in a fixed sequence with washout periods of at least one week: Phase A, a single oral dose of soy milk; Phase B, a single oral dose of soy milk coadministered with LWDHW; and Phase C, multiple oral doses of LWDHW for 14 days followed by a single oral dose of soy milk. Blood samples were collected and mixed with β-glucuronidase/sulfatase to hydrolyze isoflavone conjugates to their respective aglycones (i.e., daidzein and genistein) and were determined using high performance liquid chromatography. The pharmacokinetic parameters analyzed were maximal plasma concentration (C_max), time to reach peak concentration (T_max), area under the plasma concentration-time curve (AUC), and half-life (t_1/2). The results found no statistically significant differences in pharmacokinetic parameters of daidzein and genistein among the three regimens.

Analysis of 10 metabolites of polymethoxyflavones with high sensitivity by electrochemical detection in high-performance liquid chromatography

Polymethoxyflavones (PMFs) have been known as a type of bioactive flavones that possess various beneficial biological functions. Accumulating evidence demonstrated that the metabolites of PMFs, that is, hydroxyl PMFs (OH-PMFs), had more potent beneficial biological effects than their corresponding parent PMFs. To facilitate the further identification and quantification of OH-PMFs in biological samples, the aim of this study was to develop a methodology for the simultaneous determination of 10 OH-PMFs using high-performance liquid chromatography (HPLC) coupled with electrochemistry detection. The HPLC profiles of these 10 OH-PMFs affected by different chromatographic parameters (different organic composition in mobile phases, the concentration of trifluoroacetic acid, and the concentration of ammonium acetate) are fully discussed in this study. The optimal condition was selected for the following validation studies. The linearity of calibration curves, accuracy, and precision (intra- and interday) at three concentration levels (low, middle, and high concentration range) were verified. The regression equations were linear (r > 0.9992) over the range of 0.005-10 μM. The limit of detection for 10 OH-PMFs was in the range of 0.8-3.7 ng/mL (S/N = 3, 10 μL injection). The recovery rates ranged from 86.6 to 108.7%. The precisions of intraday and interday analyses were less than 7.37 and 8.63% for relative standard deviation, respectively. This validated method was applied for the analysis of a variety of samples containing OH-PMFs. This paper also gives an example of analyzing the metabolites of nobiletin in mouse urine using the developed method. The transformation from nobiletin to traces of 5-hydroxyl metabolites has been discovered by this effective method, and this is the first paper to report such an association.

Effect of synbiotic fermented milk on oral bioavailability of isoflavones in postmenopausal women

The purpose of this study was to investigate the effect of synbiotic fermented milk, containing Lactobacillus paracasei and inulin, on oral bioavailability and pharmacokinetics of isoflavones in healthy postmenopausal women. The study was a one-group pre-post treatment study. Twelve subjects were assigned to consume a single oral dose of 375 mL of soy beverage. Blood samples were collected immediately before and at various time points until 32 hours after the administration of the soy beverage. After a washout period, subjects were requested to consume 180 mL of synbiotic fermented milk after breakfast and dinner for 14 days, followed by a single oral dose of 375 mL of soy beverage on the next day. Collection of blood samples after the administration of the soy beverage were performed at the same time points as the former phase. Plasma isoflavone concentrations were measured by using high-performance liquid chromatography (HPLC) technique. In conclusion, this study highlighted that continuous consumption of synbiotic fermented milk followed by a single oral administration of soy beverage significantly enhanced oral bioavailability of isoflavones compared with a single oral dose of soy beverage alone.

Dietary factors affecting polyphenol bioavailability

While many epidemiological studies have associated the consumption of polyphenols within fruits and vegetables with a decreased risk of developing several chronic diseases, intervention studies have generally not confirmed these beneficial effects. The reasons for this discrepancy are not fully understood but include potential differences in dosing, interaction with the food matrix, and differences in polyphenol bioavailability. In addition to endogenous factors such as microbiota and digestive enzymes, the food matrix can also considerably affect bioaccessibility, uptake, and further metabolism of polyphenols. While dietary fiber (such as hemicellulose), divalent minerals, and viscous and protein-rich meals are likely to cause detrimental effects on polyphenol bioaccessibility, digestible carbohydrates, dietary lipids (especially for hydrophobic polyphenols, e.g., curcumin), and additional antioxidants may enhance polyphenol availability. Following epithelial uptake, polyphenols such as flavonoids may reduce phase II metabolism and excretion, enhancing polyphenol bioavailability. Furthermore, polyphenols may act synergistically due to their influence on efflux transporters such as p-glycoprotein. In order to understand polyphenol bioactivity, increased knowledge of the factors affecting polyphenol bioavailability, including dietary factors, is paramount.

Effect of a mixture of calcium, vitamin D, inulin and soy isoflavones on bone metabolism in post-menopausal women: a retrospective analysis

OBJECTIVES

Aging might affect the effectiveness of the sole supplementation of calcium and vitamin D in post-menopausal women, due to the development of vitamin D resistance in the gut, which limits calcium absorption. Thus, we wanted to test the efficacy of a mixture of calcium (500 mg), 25-hydroxyvitamin D [25(OH)D; 300 IU], inulin (3 g) and soy isoflavones (40 mg), to improve calcium absorption in this type of population.

STUDY DESIGN

It is a retrospective study on otherwise healthy post-menopausal women.

MAIN OUTCOME MEASURES

The following parameters were evaluated at baseline and after 3 months of supplementation: daily calciuria as an indirect marker of calcium absorption, serum 25(OH)D, parathormone, insulin-like growth factor 1 (IGF1) as a marker of bone anabolism, collagen telopeptide and osteocalcin as markers of bone resorption and bone turnover, respectively.

RESULTS

Twenty-eight women (median age 67 years) were included in the analysis. The supplementation markedly increased daily calciuria (+60 %; p = 0.00009), while reducing parathormone levels (-18 %; p = 0.02) and leaving 25(OH)D unaltered. An increase in IGF1 (+16 %; p = 0.01) and a reduction in collagen telopeptide (-17 %; p = 0.04) were observed, too, as well as a modest trend towards osteocalcin reduction, although not significant.

CONCLUSIONS

These results suggest that the considered mixture improved intestinal calcium absorption and bone metabolism in post-menopausal women. Since the amount of supplemented calcium was relatively low and 25(OH)D levels were unchanged, the observed effects are likely due to the combined contributions of inulin and soy isoflavones.

Isoflavones: estrogenic activity, biological effect and bioavailability

Isoflavones are phytoestrogens with potent estrogenic activity; genistein, daidzein and glycitein are the most active isoflavones found in soy beans. Phytoestrogens have similarity in structure with the human female hormone 17-β-estradiol, which can bind to both alpha and beta estrogen receptors, and mimic the action of estrogens on target organs, thereby exerting many health benefits when used in some hormone-dependent diseases. Numerous clinical studies claim benefits of genistein and daidzein in chemoprevention of breast and prostate cancer, cardiovascular disease and osteoporosis as well as in relieving postmenopausal symptoms. The ability of isoflavones to prevent cancer and other chronic diseases largely depends on pharmacokinetic properties of these compounds, in particular absorption and distribution to the target tissue. The chemical form in which isoflavones occur is important because it influences their bioavailability and, therefore, their biological activity. Glucose-conjugated isoflavones are highly polar, water-soluble compounds. They are hardly absorbed by the intestinal epithelium and have weaker biological activities than the corresponding aglycone. Different microbial families of colon can transform glycosylated isoflavones into aglycones. Clinical studies show important differences between the aglycone and conjugated forms of genistein and daidzein. The evaluation of isoflavone metabolism and bioavailability is crucial to understanding their biological effects. Lipid-based formulations such as drug incorporation into oils, emulsions and self-microemulsifying formulations have been introduced to increase bioavailability. Complexation with cyclodextrin also represent a valid method to improve the physicochemical characteristics of these substances in order to be absorbed and distributed to target tissues. We review and discuss pharmacokinetic issues that critically influence the biological activity of isoflavones.

Influence of fructooligosaccharide on pharmacokinetics of isoflavones in postmenopausal women

The objective of the present paper was to determine the influence of fructooligosaccharide (FOS) on the pharmacokinetics of isoflavones in healthy postmenopausal women. The study was a fixed-sequence, two-phase, crossover study. Twelve subjects received a single oral dose of 300 mL of a soy beverage. Blood samples were collected before the dose and at 0.5, 1, 2, 4, 6, 8, 10, 12, 24, and 32 h after the administration of the soy beverage. After a washout period of at least 1 week, subjects were assigned to receive oral doses of FOS, 5 g each time, twice a day (after breakfast and dinner) for 14 days, followed by a single oral dose of the same soy beverage on the next day. Blood samples were then collected at the same time points mentioned previously. Plasma isoflavone concentrations were determined by HPLC. Continuous oral administrations of FOS followed by a single oral administration of soy beverage caused significant increases in C_max, AUC_0–32, and AUC_0–∞ of genistein and AUC_0–32 of daidzein, comparing to those obtained following a single oral dose of soy beverage alone. Other pharmacokinetic parameters (T_max and t_1/2 of both aglycones and AUC_0–∞ of daidzein) between both regimens were not significantly different.

Prebiotic effects: metabolic and health benefits

The different compartments of the gastrointestinal tract are inhabited by populations of micro-organisms. By far the most important predominant populations are in the colon where a true symbiosis with the host exists that is a key for well-being and health. For such a microbiota, 'normobiosis' characterises a composition of the gut 'ecosystem' in which micro-organisms with potential health benefits predominate in number over potentially harmful ones, in contrast to 'dysbiosis', in which one or a few potentially harmful micro-organisms are dominant, thus creating a disease-prone situation. The present document has been written by a group of both academic and industry experts (in the ILSI Europe Prebiotic Expert Group and Prebiotic Task Force, respectively). It does not aim to propose a new definition of a prebiotic nor to identify which food products are classified as prebiotic but rather to validate and expand the original idea of the prebiotic concept (that can be translated in 'prebiotic effects'), defined as: 'The selective stimulation of growth and/or activity(ies) of one or a limited number of microbial genus(era)/species in the gut microbiota that confer(s) health benefits to the host.' Thanks to the methodological and fundamental research of microbiologists, immense progress has very recently been made in our understanding of the gut microbiota. A large number of human intervention studies have been performed that have demonstrated that dietary consumption of certain food products can result in statistically significant changes in the composition of the gut microbiota in line with the prebiotic concept. Thus the prebiotic effect is now a well-established scientific fact. The more data are accumulating, the more it will be recognised that such changes in the microbiota's composition, especially increase in bifidobacteria, can be regarded as a marker of intestinal health. The review is divided in chapters that cover the major areas of nutrition research where a prebiotic effect has tentatively been investigated for potential health benefits. The prebiotic effect has been shown to associate with modulation of biomarkers and activity(ies) of the immune system. Confirming the studies in adults, it has been demonstrated that, in infant nutrition, the prebiotic effect includes a significant change of gut microbiota composition, especially an increase of faecal concentrations of bifidobacteria. This concomitantly improves stool quality (pH, SCFA, frequency and consistency), reduces the risk of gastroenteritis and infections, improves general well-being and reduces the incidence of allergic symptoms such as atopic eczema. Changes in the gut microbiota composition are classically considered as one of the many factors involved in the pathogenesis of either inflammatory bowel disease or irritable bowel syndrome. The use of particular food products with a prebiotic effect has thus been tested in clinical trials with the objective to improve the clinical activity and well-being of patients with such disorders. Promising beneficial effects have been demonstrated in some preliminary studies, including changes in gut microbiota composition (especially increase in bifidobacteria concentration). Often associated with toxic load and/or miscellaneous risk factors, colon cancer is another pathology for which a possible role of gut microbiota composition has been hypothesised. Numerous experimental studies have reported reduction in incidence of tumours and cancers after feeding specific food products with a prebiotic effect. Some of these studies (including one human trial) have also reported that, in such conditions, gut microbiota composition was modified (especially due to increased concentration of bifidobacteria). Dietary intake of particular food products with a prebiotic effect has been shown, especially in adolescents, but also tentatively in postmenopausal women, to increase Ca absorption as well as bone Ca accretion and bone mineral density. Recent data, both from experimental models and from human studies, support the beneficial effects of particular food products with prebiotic properties on energy homaeostasis, satiety regulation and body weight gain. Together, with data in obese animals and patients, these studies support the hypothesis that gut microbiota composition (especially the number of bifidobacteria) may contribute to modulate metabolic processes associated with syndrome X, especially obesity and diabetes type 2. It is plausible, even though not exclusive, that these effects are linked to the microbiota-induced changes and it is feasible to conclude that their mechanisms fit into the prebiotic effect. However, the role of such changes in these health benefits remains to be definitively proven. As a result of the research activity that followed the publication of the prebiotic concept 15 years ago, it has become clear that products that cause a selective modification in the gut microbiota's composition and/or activity(ies) and thus strengthens normobiosis could either induce beneficial physiological effects in the colon and also in extra-intestinal compartments or contribute towards reducing the risk of dysbiosis and associated intestinal and systemic pathologies.

Simultaneous determination of four 5-hydroxy polymethoxyflavones by reversed-phase high performance liquid chromatography with electrochemical detection

Accumulating evidence has suggested the potential health-promoting effects of 5-hydroxy polymethoxyflavones (5-OH-PMFs) naturally existing in citrus genus. However, research efforts are hampered by the lack of reliable and sensitive methods for their determination in plant materials and biological samples. Using reversed-phase high performance liquid chromatography (HPLC) equipped with electrochemical (EC) detection, we have developed a fast and highly sensitive method for quantification of four 5-OH-PMFs, namely 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone, 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone, 5-hydroxy-6,7,4'-trimethoxyflavone, and 5-hydroxy-6,7,8,4'-tetramethoxyflavone. The method was fully validated in terms of linearity, accuracy and precision. The limit of detection (LOD) was determined as being between 0.65 and 1.8ng/mL (ppb), demonstrating an over 160 times higher sensitivity in comparison with the previously reported method using UV detection. The recovery rate of the method was between 96.17% and 110.82%, and the precision for the retention times and peak areas was all below 13%. The method was successfully used to quantify 5-OH-PMFs with a wide range of abundance in the citrus products and preparations, such as orange juice, citrus peel, and dried tangerine peel. The quantification method for 5-OH-PMFs developed herein could be useful for the nutritional and pharmacological studies of these compounds in future.

The pharmacokinetic behavior of the soy isoflavone metabolite S-(-)equol and its diastereoisomer R-(+)equol in healthy adults determined by using stable-isotope-labeled tracers

BACKGROUND

The nonsteroidal estrogen equol occurs as diastereoisomers, S-(-)equol and R-(+)equol, both of which have significant biological actions. S-(-)equol, the naturally occurring enantiomer produced by 20-30% of adults consuming soy foods, has selective affinity for estrogen receptor-beta, whereas both enantiomers modulate androgen action. Little is known about the pharmacokinetics of the diastereoisomers, despite current interest in developing equol as a nutraceutical or pharmaceutical agent.

OBJECTIVE

The objective was to compare the pharmacokinetics of S-(-)equol and R-(+)equol by using [13C] stable-isotope-labeled tracers to facilitate the optimization of clinical studies aimed at evaluating the potential of these diastereoisomers in the prevention and treatment of estrogen- and androgen-dependent conditions.

DESIGN

A randomized, crossover, open-label study in 12 healthy adults (6 men and 6 women) compared the plasma and urinary pharmacokinetics of orally administered enantiomeric pure forms of S-(-)[2-13C]equol, R-(+)[2-13C]equol, and the racemic mixture. Plasma and urinary [13C]R-equol and [13C]S-equol concentrations were measured by tandem mass spectrometry.

RESULTS

Plasma [13C]equol concentration appearance and disappearance curves showed that both enantiomers were rapidly absorbed, attained high circulating concentrations, and had a similar terminal elimination half-life of 7-8 h. The systemic bioavailability and fractional absorption of R-(+)[2-13C]equol were higher than those of S-(-)[2-13C]equol or the racemate. The pharmacokinetics of racemic (+/-)[2-13C]equol were different from those of the individual enantiomers: slower absorption, lower peak plasma concentrations, and lower systemic bioavailability.

CONCLUSIONS

The high bioavailability of both diastereoisomers contrasts with previous findings for the soy isoflavones daidzein and genistein, both of which have relatively poor bioavailability, and suggests that low doses of equol taken twice daily may be sufficient to achieve biological effects.

Attitudes and knowledge toward natural products safety in the pharmacy setting: an Italian study

The lack of a professional supervision may expose consumers of natural products to risks; pharmacists play an important role in giving information about these substances. A survey was designed to investigate the attitudes and knowledge of consumers and pharmacists toward the safety of natural products. Twenty-three pharmacies participated in the project. On the basis of a pre-structured 17-item questionnaire, face-to-face interviews were conducted with consumers buying a natural product over a 6-month period. A further 8 items had to be compiled by pharmacists about the purchased product. During the study period, 1420 interviews were carried out. The most frequently purchased products were echinacea, propolis, garlic, guggul, ginkgo, liquorice, ginseng, glucomannan, guarana, valerian, and passionflower; 71.8% of consumers reported to have been taking conventional medicines along with natural products. Some (3.9%) referred to adverse effects in the last year: allergic reactions after cartilage of shark, propolis and thyme; anxiety after hypericum; hypotension and tachycardia after a mix containing chamomile, valerian and melissa; pyrosis and stomach-ache after laxative-depurative herbs. Pharmacists referred to some adverse effects observed in the past in relation to the products bought by consumers involved in this study. Findings from this study demonstrate that in general consumers need information on herbal safety and pharmacists are more likely to answer correctly about the use of herbs rather than about cautions, adverse effects and interactions.