RESUMO
PURPOSE: (Poly)phenols have been reported to confer protective effects against type 2 diabetes but the precise association remains elusive. This meta-analysis aimed to assess the effects of (poly)phenol intake on well-established biomarkers in people with type 2 diabetes or at risk of developing diabetes. METHODS: A systematic search was conducted using the following selection criteria: (1) human randomized controlled trials involving individuals with prediabetes and type 2 diabetes; (2) one or more of the following biomarkers: glucose, glycated haemoglobin (HbA1c), insulin, pro-insulin, homeostatic model assessment of insulin resistance (HOMA-IR), islet amyloid polypeptide (IAPP)/amylin, pro-IAPP/pro-amylin, glucagon, C-peptide; (3) chronic intervention with pure or enriched mixtures of (poly)phenols. From 488 references, 88 were assessed for eligibility; data were extracted from 27 studies and 20 were used for meta-analysis. The groups included in the meta-analysis were: (poly)phenol mixtures, isoflavones, flavanols, anthocyanins and resveratrol. RESULTS: Estimated intervention/control mean differences evidenced that, overall, the consumption of (poly)phenols contributed to reduced fasting glucose levels (- 3.32 mg/dL; 95% CI - 5.86, - 0.77; P = 0.011). Hb1Ac was only slightly reduced (- 0.24%; 95% CI - 0.43, - 0.044; P = 0.016) whereas the levels of insulin and HOMA-IR were not altered. Subgroup comparative analyses indicated a stronger effect on blood glucose in individuals with diabetes (- 5.86 mg/dL, 95% CI - 11.34, - 0.39; P = 0.036) and this effect was even stronger in individuals taking anti-diabetic medication (- 10.17 mg/dL, 95% CI - 16.59, - 3.75; P = 0.002). CONCLUSIONS: Our results support that the consumption of (poly)phenols may contribute to lower glucose levels in individuals with type 2 diabetes or at risk of diabetes and that these compounds may also act in combination with anti-diabetic drugs.
Assuntos
Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/sangue , Hipoglicemiantes/uso terapêutico , Fenóis/sangue , Fenóis/uso terapêutico , Biomarcadores/sangue , Terapia Combinada/métodos , Humanos , Polifenóis/sangue , Polifenóis/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Wholegrain oats are known to modulate the human gut microbiota and have prebiotic properties (increase the growth of some health-promoting bacterial genera within the colon). Research to date mainly attributes these effects to the fibre content; however, oat is also a rich dietary source of polyphenols, which may contribute to the positive modulation of gut microbiota. In vitro anaerobic batch-culture experiments were performed over 24 h to evaluate the impact of two different doses (1 and 3 % (w/v)) of oat bran, matched concentrations of ß-glucan extract or polyphenol mix, on the human faecal microbiota composition using 16S RNA gene sequencing and SCFA analysis. Supplementation with oats increased the abundance of Proteobacteria (P <0·01) at 10 h, Bacteroidetes (P <0·05) at 24 h and concentrations of acetic and propionic acid increased at 10 and 24 h compared with the NC. Fermentation of the 1 % (w/v) oat bran resulted in significant increase in SCFA production at 24 h (86 (sd 27) v. 28 (sd 5) mm; P <0·05) and a bifidogenic effect, increasing the relative abundance of Bifidobacterium unassigned at 10 h and Bifidobacterium adolescentis (P <0·05) at 10 and 24 h compared with NC. Considering the ß-glucan treatment induced an increase in the phylum Bacteroidetes at 24 h, it explains the Bacteriodetes effects of oats as a food matrix. The polyphenol mix induced an increase in Enterobacteriaceae family at 24 h. In conclusion, in this study, we found that oats increased bifidobacteria, acetic acid and propionic acid, and this is mediated by the synergy of all oat compounds within the complex food matrix, rather than its main bioactive ß-glucan or polyphenols. Thus, oats as a whole food led to the greatest impact on the microbiota.
Assuntos
Avena/química , Bacteroidetes/efeitos dos fármacos , Bifidobacterium/efeitos dos fármacos , Microbioma Gastrointestinal/efeitos dos fármacos , Grãos Integrais , Ácido Acético/metabolismo , Fezes/microbiologia , Fermentação/efeitos dos fármacos , Humanos , Polifenóis/farmacologia , Prebióticos , Propionatos/metabolismo , Proteobactérias/efeitos dos fármacos , beta-Glucanas/farmacologiaRESUMO
Oats contain a range of phenolic acids and avenanthramides which may have health benefits. Analysis of 22 commercial oat products (oat bran concentrate, oat bran, flaked oats, rolled oats and oatcakes) using HPLC-DAD detected eleven bound and thirteen freeâ¯+â¯conjugated phenolic acids and avenanthramides. The oat products (excluding concentrate) provided between 15.79 and 25.05â¯mg total phenolic acids (9.9-19.33â¯mg bound, 4.96-5.72â¯mg freeâ¯+â¯conjugated) and between 1.1 and 2â¯mg of avenanthramides in a 40â¯g portion while an 11â¯g portion of oat concentrate provided 16.7â¯mg of total phenolic acids (15.17â¯mg bound, 1.53â¯mg freeâ¯+â¯conjugated) and 1.2â¯mg of avenanthramides. The compositions and concentrations of the components in the different products were broadly similar, with the major component being ferulic acid (58-78.1%). The results show that commercial oat products are a source of phenolic acids and avenanthramides for consumers.
RESUMO
SCOPE: Wholegrain has been associated with reduced chronic disease mortality, with oat intake particularly notable for lowering blood cholesterol and glycemia. To better understand the complex nutrient profile of oats, we studied urinary excretion of phenolic acids and avenanthramides after ingestion of oat bran in humans. METHODS AND RESULTS: After a 2-d (poly)phenol-low diet, seven healthy men provided urine 12 h before and 48 h after consuming 60 g oat bran (7.8 µmol avenanthramides, 139.2 µmol phenolic acids) or a phenolic-low (traces of phenolics) control in a crossover design. Analysis by ultra-high performance liquid chromatography (UPLC)-MS/MS showed that oat bran intake resulted in an elevation in urinary excretion of 30 phenolics relative to the control, suggesting that they are oat bran-derived. Mean excretion levels were elevated between 0-2 and 4-8 h, following oat bran intake, and amounted to a total of 33.7 ± 7.3 µmol total excretion (mean recovery: 22.9 ± 5.0%), relative to control. The predominant metabolites included: vanillic acid, 4- and 3-hydroxyhippuric acids, and sulfate-conjugates of benzoic and ferulic acids, which accounted collectively for two thirds of total excretion. CONCLUSION: Oat bran phenolics follow a relatively rapid urinary excretion, with 30 metabolites excreted within 8 h of intake. These levels of excretion suggest that bound phenolics are, in part, rapidly released by the microbiota.
Assuntos
Avena , Hidroxibenzoatos/urina , ortoaminobenzoatos/urina , Adulto , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Hidroxibenzoatos/administração & dosagem , Hidroxibenzoatos/farmacocinética , Masculino , Pessoa de Meia-Idade , Espectrometria de Massas em Tandem/métodos , ortoaminobenzoatos/administração & dosagem , ortoaminobenzoatos/farmacocinéticaRESUMO
Several epidemiological studies have linked flavonols with decreased risk of cardiovascular disease (CVD). However, some heterogeneity in the individual physiological responses to the consumption of these compounds has been identified. This meta-analysis aimed to study the effect of flavonol supplementation on biomarkers of CVD risk such as, blood lipids, blood pressure and plasma glucose, as well as factors affecting their inter-individual variability. Data from 18 human randomized controlled trials were pooled and the effect was estimated using fixed or random effects meta-analysis model and reported as difference in means (DM). Variability in the response of blood lipids to supplementation with flavonols was assessed by stratifying various population subgroups: age, sex, country, and health status. Results showed significant reductions in total cholesterol (DM = -0.10 mmol/L; 95% CI: -0.20, -0.01), LDL cholesterol (DM = -0.14 mmol/L; Nutrients 2017, 9, 117 2 of 21 95% CI: -0.21, 0.07), and triacylglycerol (DM = -0.10 mmol/L; 95% CI: -0.18, 0.03), and a significant increase in HDL cholesterol (DM = 0.05 mmol/L; 95% CI: 0.02, 0.07). A significant reduction was also observed in fasting plasma glucose (DM = -0.18 mmol/L; 95%CI: -0.29, -0.08), and in blood pressure (SBP: DM = -4.84 mmHg; 95% CI: -5.64, -4.04; DBP: DM = -3.32 mmHg; 95% CI: -4.09, -2.55). Subgroup analysis showed a more pronounced effect of flavonol intake in participants from Asian countries and in participants with diagnosed disease or dyslipidemia, compared to healthy and normal baseline values. In conclusion, flavonol consumption improved biomarkers of CVD risk, however, country of origin and health status may influence the effect of flavonol intake on blood lipid levels.
Assuntos
Doenças Cardiovasculares/prevenção & controle , Suplementos Nutricionais , Flavonóis/administração & dosagem , Adulto , Ásia , Biomarcadores/sangue , Pressão Sanguínea , Doenças Cardiovasculares/etiologia , Colesterol/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Feminino , Humanos , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Ensaios Clínicos Controlados Aleatórios como Assunto , Fatores de RiscoRESUMO
BACKGROUND: There is much speculation with regard to the potential cardioprotective benefits of equol, a microbial-derived metabolite of the isoflavone daidzein, which is produced in the large intestine after soy intake in 30% of Western populations. Although cross-sectional and retrospective data support favorable associations between the equol producer (EP) phenotype and cardiometabolic health, few studies have prospectively recruited EPs to confirm this association. OBJECTIVE: The aim was to determine whether the acute vascular benefits of isoflavones differ according to EP phenotype and subsequently investigate the effect of providing commercially produced S-(-)equol to non-EPs. DESIGN: We prospectively recruited male EPs and non-EPs (n = 14/group) at moderate cardiovascular risk into a double-blind, placebo-controlled crossover study to examine the acute effects of soy isoflavones (80-mg aglycone equivalents) on arterial stiffness [carotid-femoral pulse-wave velocity (cfPWV)], blood pressure, endothelial function (measured by using the EndoPAT 2000; Itamar Medical), and nitric oxide at baseline (0 h) and 6 and 24 h after intake. In a separate assessment, non-EPs consumed 40 mg S-(-)equol with identical vascular measurements performed 2 h after intake. RESULTS: After soy intake, cfPWV significantly improved in EPs at 24 h (cfPWV change from 0 h: isoflavone, -0.2 ± 0.2 m/s; placebo, 0.6 ± 0.2 m/s; P < 0.01), which was significantly associated with plasma equol concentrations (R = -0.36, P = 0.01). No vascular effects were observed in EPs at 6 h or in non-EPs at any time point. Similarly, no benefit of commercially produced S-(-)equol was observed in non-EPs despite mean plasma equol concentrations reaching 3.2 µmol/L. CONCLUSIONS: Acute soy intake improved cfPWV in EPs, equating to an 11-12% reduced risk of cardiovascular disease if sustained. However, a single dose of commercially produced equol had no cardiovascular benefits in non-EPs. These data suggest that the EP phenotype is critical in unlocking the vascular benefits of equol in men, and long-term trials should focus on confirming the implications of EP phenotype on cardiovascular health. This trial was registered at clinicaltrials.gov as NCT01530893.
Assuntos
Bactérias/metabolismo , Doenças Cardiovasculares , Equol , Glycine max/química , Isoflavonas/farmacologia , Fenótipo , Rigidez Vascular/efeitos dos fármacos , Idoso , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/fisiopatologia , Doenças Cardiovasculares/prevenção & controle , Estudos Cross-Over , Estudos Transversais , Suplementos Nutricionais , Método Duplo-Cego , Equol/biossíntese , Equol/sangue , Equol/farmacologia , Microbioma Gastrointestinal , Humanos , Isoflavonas/metabolismo , Isoflavonas/uso terapêutico , Masculino , Pessoa de Meia-Idade , Fitoestrógenos/metabolismo , Fitoestrógenos/farmacologia , Fitoestrógenos/uso terapêutico , Fitoterapia , Extratos Vegetais/metabolismo , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Estudos Prospectivos , Análise de Onda de Pulso , Rigidez Vascular/fisiologiaRESUMO
BACKGROUND: Epidemiologic data suggest inverse associations between citrus flavanone intake and cardiovascular disease (CVD) risk. However, insufficient randomized controlled trial data limit our understanding of the mechanisms by which flavanones and their metabolites potentially reduce cardiovascular risk factors. OBJECTIVE: We examined the effects of orange juice or a dose-matched hesperidin supplement on plasma concentrations of established and novel flavanone metabolites and their effects on cardiovascular risk biomarkers in men at moderate CVD risk. DESIGN: In an acute, randomized, placebo-controlled crossover trial, 16 fasted participants (aged 51-69 y) received orange juice or a hesperidin supplement (both providing 320 mg hesperidin) or control (all matched for sugar and vitamin C content). At baseline and 5 h postintake, endothelial function (primary outcome), blood pressure, arterial stiffness, cardiac autonomic function, platelet activation, and NADPH oxidase gene expression and plasma flavanone metabolites were assessed. Before each intervention, a diet low in flavonoids, nitrate/nitrite, alcohol, and caffeine was followed, and a standardized low-flavonoid evening meal was consumed. RESULTS: Orange juice intake significantly elevated mean ± SEM plasma concentrations of 8 flavanone (1.75 ± 0.35 µmol/L, P < 0.0001) and 15 phenolic (13.27 ± 2.22 µmol/L, P < 0.0001) metabolites compared with control at 5 h postconsumption. Despite increased plasma flavanone and phenolic metabolite concentrations, cardiovascular risk biomarkers were unaltered. After hesperidin supplement intake, flavanone metabolites were not different from the control, suggesting altered absorption/metabolism compared with the orange juice matrix. CONCLUSIONS: After single-dose flavanone intake within orange juice, circulating flavanone and phenolic metabolites collectively reached a concentration of 15.20 ± 2.15 µmol/L, but no effects were observed on cardiovascular risk biomarkers. Longer-duration randomized controlled trials are required to examine previous associations between higher flavanone intakes and improved cardiovascular health and to ascertain the relative importance of food matrix and flavanone-derived phenolic metabolites. This trial was registered at clinicaltrials.gov as NCT01530893.