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The American Journal of Clinical... Jul 2018Type 2 diabetes is characterized by impaired glucose metabolism. Bioactive compounds in fruits and vegetables such as polyphenols have been suggested to influence... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Type 2 diabetes is characterized by impaired glucose metabolism. Bioactive compounds in fruits and vegetables such as polyphenols have been suggested to influence glucose metabolism.
OBJECTIVE
The aim of the current study was to systematically review the literature and conduct dose-response meta-analyses to summarize evidence of polyphenol exposure in association with incident type 2 diabetes.
DESIGN
Prospective epidemiologic studies published before January 2018 were searched through 2 databases. Log-transformed multivariable adjusted hazard and odds ratios were combined in a random-effects model. Meta-analyses comparing extreme quantiles of polyphenol exposure were further explored with the use of linear and nonlinear dose-response meta-analyses.
RESULTS
Eighteen studies investigated the association between polyphenols (51 different compounds in total) and type 2 diabetes. A comparison of extreme quantiles revealed inverse associations for intakes of polyphenols (HR: 0.56; 95% CI: 0.34, 0.93), flavonoids (HR: 0.88; 95% CI: 0.81, 0.96), flavonols (HR: 0.92; 95% CI: 0.85, 0.98), flavan-3-ols (HR: 0.89; 95% CI: 0.81, 0.99), catechins (HR: 0.86; 95% CI: 0.75, 0.97), anthocyanidins (HR: 0.86; 95% CI: 0.81, 0.91), isoflavones (HR: 0.92; 0.86, 0.97), daidzein (HR: 0.89; 95% CI: 0.83, 0.95), genistein (HR: 0.92; 95% CI: 0.86, 0.99), and stilbenes (HR: 0.44; 95% CI: 0.26, 0.72), and biomarkers of daidzein (HR: 0.81; 95% CI: 0.66, 0.99) and genistein (HR: 0.79; 95% CI: 0.62, 0.99). In the dose-response meta-analysis, nonlinear associations were observed for intakes of polyphenols, flavonoids, flavanones, anthocyanidins, anthocyanins, and biomarkers of genistein. A linear dose-response association was observed for phenolic acids.
CONCLUSIONS
This study adds to the evidence showing that diets rich in polyphenols, and particularly flavonoids, play a role in the prevention of type 2 diabetes. For most associations evidence for nonlinearity was found, suggesting a recommendable amount of intake associated with the lowest risk of type 2 diabetes. Therefore, future studies are warranted in which nonlinear associations are further explored.
Topics: Cohort Studies; Diabetes Mellitus, Type 2; Diet; Dose-Response Relationship, Drug; Food Analysis; Humans; Polyphenols
PubMed: 29931039
DOI: 10.1093/ajcn/nqy083 -
Nutrients Jan 2018Prostate cancer (PCa) is the second most commonly diagnosed cancer in men, accounting for 15% of all cancers in men worldwide. Asian populations consume soy foods as... (Meta-Analysis)
Meta-Analysis Review
Prostate cancer (PCa) is the second most commonly diagnosed cancer in men, accounting for 15% of all cancers in men worldwide. Asian populations consume soy foods as part of a regular diet, which may contribute to the lower PCa incidence observed in these countries. This meta-analysis provides a comprehensive updated analysis that builds on previously published meta-analyses, demonstrating that soy foods and their isoflavones (genistein and daidzein) are associated with a lower risk of prostate carcinogenesis. Thirty articles were included for analysis of the potential impacts of soy food intake, isoflavone intake, and circulating isoflavone levels, on both primary and advanced PCa. Total soy food ( < 0.001), genistein ( = 0.008), daidzein ( = 0.018), and unfermented soy food ( < 0.001) intakes were significantly associated with a reduced risk of PCa. Fermented soy food intake, total isoflavone intake, and circulating isoflavones were not associated with PCa risk. Neither soy food intake nor circulating isoflavones were associated with advanced PCa risk, although very few studies currently exist to examine potential associations. Combined, this evidence from observational studies shows a statistically significant association between soy consumption and decreased PCa risk. Further studies are required to support soy consumption as a prophylactic dietary approach to reduce PCa carcinogenesis.
Topics: Adult; Aged; Aged, 80 and over; Anticarcinogenic Agents; Asian People; Diet; Humans; Male; Middle Aged; Nutritive Value; Odds Ratio; Prostatic Neoplasms; Protective Factors; Risk Factors; Risk Reduction Behavior; Soy Foods
PubMed: 29300347
DOI: 10.3390/nu10010040 -
Nutrition Reviews Aug 2017Isoflavones have been suggested to play a role in disease prevention. The accuracy of assessing exposure to isoflavones might be improved by using them as biomarkers. (Meta-Analysis)
Meta-Analysis Review
CONTEXT
Isoflavones have been suggested to play a role in disease prevention. The accuracy of assessing exposure to isoflavones might be improved by using them as biomarkers.
OBJECTIVE
A systematic review of observational studies on the association of isoflavone biomarkers with the risk of chronic disease and mortality was conducted. Meta-analyses of specific biomarker and disease combinations were performed.
DATA SOURCES
PubMed and Web of Science databases were searched.
DATA EXTRACTION
Two authors screened the titles and abstracts of candidate publications. The third author was consulted to resolve discrepancies. Forty studies were included and their quality assessed. PRISMA-P guidelines were followed.
DATA ANALYSIS
Eight different isoflavone biomarkers were investigated in association with cancer (26 studies), mortality (2 studies), cardiovascular disease (3 studies), metabolic syndrome risk factors (7 studies), and other outcomes (2 studies). Meta-analyses of studies on individual isoflavonic compounds were conducted for breast and prostate cancer and type 2 diabetes. Higher daidzein and genistein concentrations were associated with lower risk of breast cancer and diabetes. Only daidzein concentrations were inversely associated with risk of prostate cancer. For the remaining endpoints, evidence for associations was inconsistent and scarce, perhaps owing to heterogeneity in study exposures and outcomes.
CONCLUSIONS
Further research using biomarker information is warranted.
Topics: Biomarkers; Breast Neoplasms; Cardiovascular Diseases; Chronic Disease; Databases, Factual; Diabetes Mellitus, Type 2; Female; Genistein; Humans; Isoflavones; Male; Metabolic Syndrome; Neoplasms; Prostatic Neoplasms; Risk Factors
PubMed: 28969363
DOI: 10.1093/nutrit/nux021 -
Food Chemistry Jan 2018Translating food intake data into phytochemical outcomes is a crucial step in investigating potential health benefits. The aim of this review was to examine the tools... (Review)
Review
Translating food intake data into phytochemical outcomes is a crucial step in investigating potential health benefits. The aim of this review was to examine the tools for determining dietary-derived polyphenol intakes for estimated intake studies. Published studies from 2004 to 2014 reporting polyphenol food composition information were sourced with 157 studies included. Six polyphenol subclasses were identified. One quarter of studies (n=39) reported total flavonoids intake with 27% reporting individual flavonoid compounds. Assessing multiple compounds was common with approximately 10% of studies assessing seven (n=13), six (n=12) and five (n=14) subclasses of polyphenol. There was no pattern between reported flavonoids compounds and subclass studied. Approximately 60% of studies relied on publicly accessible food composition data to estimate dietary polyphenols intake with 33% using two or more tools. This review highlights the importance of publicly accessible composition databases for estimating polyphenol intake and provides a reference for tools available globally.
Topics: Databases, Factual; Diet; Flavonoids; Food; Humans; Polyphenols
PubMed: 28867085
DOI: 10.1016/j.foodchem.2016.11.010 -
Current Drug Targets 2017The evolution of the Green movement in western society has changed attitudes in the general population who now perceive natural compounds as being inherently harmless... (Review)
Review
BACKGROUND
The evolution of the Green movement in western society has changed attitudes in the general population who now perceive natural compounds as being inherently harmless and more desirable than artificial chemical products.
OBJECTIVE
Considering the growing interest towards introducing naturally emerged medicines, the purpose of this review was to overview the ongoing research into prevention and treatment of multiple sclerosis (MS) lesions.
METHOD
This review was carried out by searching bibliographic databases such as PubMed and Scopus for studies reported between 1st January 2008 to 30th January 2016 on MS patients or animal models of MS, investigating the beneficial effects of natural compounds in MS treatment. In this updated systematic review, the search terms were "multiple sclerosis" or "neurodegeneration" and ("natural compounds" or "medicinal plants", "traditional medicine" or "native medicine").
RESULTS
Studies with vitamins (A, B12, D, H), minerals (selenium and lithium), n-3 PUFAs, lipoic acid, statins, resveratrol, marijuana, EGCG and some probiotics have shown significant helpful effects in MS by preventing or delaying the onset of disease. Other natural compounds such as xanthines, anthocyanins, glucosinolates, isoflavones, organosulfurs, steroid glycosides, and alkaloids have also shown protective effects in the treatment of MS in animal models. Adverse effects were also reported in some of the experiments.
CONCLUSION
Further studies with a focus on the molecular mechanisms of the protective natural compounds are needed to decrease possible side effects and to develop new medicines for MS. Apigenin, chrysin, baicalein, cyanidin, flavone glycoside, daidzein, coumestrol, sulforaphane, bee venom and huperzine A are the candidates for more prospective investigations.
Topics: Animals; Biological Products; Humans; Medicine, Traditional; Multiple Sclerosis; Phytochemicals; Prospective Studies
PubMed: 27829351
DOI: 10.2174/1389450118666161108124414 -
Climacteric : the Journal of the... Dec 2016Menopause is associated with increased bone resorption and decreased bone mineral density (BMD). Phytoestrogens are believed to prevent bone loss. This study reviewed... (Review)
Review
INTRODUCTION
Menopause is associated with increased bone resorption and decreased bone mineral density (BMD). Phytoestrogens are believed to prevent bone loss. This study reviewed relevant randomized, controlled trials to determine the effects of phytoestrogens on BMD in postmenopausal women.
METHODS
In order to perform this systematic review, PubMed, Science Direct, Scopus, Cochrane Library, ISI Web of Knowledge, and ProQuest databases were searched for articles published during 2005-2016. The main keywords used during the searches were "phytoestrogen" and "bone mineral density" and "menopause". The Cochrane Risk of Bias Assessment Tool was used to evaluate the quality of the selected studies and to assess the risk of bias.
RESULTS
A total of 23 eligible studies were included in this systematic review. Most selected studies used a double-blind, placebo-controlled design. In total, 3494 participants were enrolled in the selected trials. Different types of soy isoflavone extracts, including genistein extracts (either alone or in combination with daidzein), dietary products containing different amounts of phytoestrogens, and red clover extracts were used in the designed interventions. The duration of the interventions ranged from 7 weeks to 3 years. In most studies, the primary outcome was the efficacy of the designed intervention which was assessed through measuring whole body or regional BMD or bone mineral content, T-scores, and biomarkers of bone metabolism.
CONCLUSIONS
Isoflavones probably have beneficial effects on bone health in menopausal women. Nevertheless, there were controversial reports about changes in BMD. Supplementation with a phytoestrogen can probably prevent the reduction in BMD and maintain a healthy bone structure during menopause.
Topics: Bone Density; Diet; Double-Blind Method; Female; Genistein; Humans; Isoflavones; Menopause; Phytoestrogens; Phytotherapy; Placebos; Plant Extracts; Randomized Controlled Trials as Topic; Glycine max
PubMed: 27710141
DOI: 10.1080/13697137.2016.1238451 -
Journal of Nutritional Science 2016Recent studies suggest that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial to coronary health. Equol, generated by bacterial... (Review)
Review
Recent studies suggest that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial to coronary health. Equol, generated by bacterial action on isoflavones in the human gut, is biologically more potent than dietary sources of isoflavones. Not all humans are equol producers. We investigated whether equol-producing status is favourably associated with risk factors for CHD following an intervention by dietary soya isoflavones. We systematically reviewed randomised controlled trials (RCT) that evaluated the effect of soya isoflavones on risk factors for CHD and that reported equol-producing status. We searched PubMed, EMBASE, Ovid Medline and the Cochrane Central Register for Controlled Trials published up to April 2015 and hand-searched bibliographies to identify the RCT. Characteristics of participants and outcomes measurements were extracted and qualitatively analysed. From a total of 1671 studies, we identified forty-two articles that satisfied our search criteria. The effects of equol on risk factors for CHD were mainly based on secondary analyses in these studies, thus with inadequate statistical power. Although fourteen out of the forty-two studies found that equol production after a soya isoflavone intervention significantly improved a range of risk factors including cholesterol and other lipids, inflammation and blood pressure variables, these results need further verification by sufficiently powered studies. The other twenty-eight studies primarily reported null results. RCT of equol, which has recently become available as a dietary supplement, on CHD and its risk factors are awaited.
PubMed: 27547393
DOI: 10.1017/jns.2016.18 -
Andrology Jul 2016This study uses current epidemiological data to evaluate whether phytoestrogen intake is associated with a reduced risk of prostate cancer. We performed a random-effect... (Review)
Review
This study uses current epidemiological data to evaluate whether phytoestrogen intake is associated with a reduced risk of prostate cancer. We performed a random-effect meta-analysis of published data retrieved from PubMed, Web of Science, ProQuest, and CNKI, which was supplemented by a manual search of relevant references. Study quality was assessed using the Newcastle-Ottawa Scale (NOS). Subgroup analysis and meta-regression were performed to explore the source of heterogeneity. Sensitivity analysis was evaluated to assess the stability of the results. Egger's test and funnel plots were used to detect the existence of publication bias. We retrieved 507 papers, and 29 studies were ultimately confirmed as eligible. The meta-analysis showed that phytoestrogen intake was significantly associated with a reduced risk of prostate cancer, with an odds ratio (OR) of 0.77 (95% CI 0.66-0.88; I(2) = 77.6%). The food/nutritional sources that were significantly associated with a reduced risk of prostate cancer included soy and soy products, tofu, legumes, daidzein, and genistein. Subgroup analysis indicated that the associations were significant among Asians and Caucasians, but not among Africans. Meta-regression revealed that the pooled OR increased with the number of cases in the studies. The results might be affected by publication bias based on the Eggers' test (p = 0.011) and the asymmetry of the funnel plot. Phytoestrogen intake may reduce the risk of prostate cancer in Asians and Caucasians. Regular intake of food that is rich in phytoestrogens, such as soy/soy products or legumes, should be recommended.
Topics: Humans; Incidence; Male; Phytoestrogens; Prostatic Neoplasms; Risk; Risk Reduction Behavior
PubMed: 27260185
DOI: 10.1111/andr.12196 -
Maturitas Jun 2013Dietary supplements are popular among patients with prostate cancer (PC). The objective of this systematic review was to critically examine double-blind,... (Review)
Review
Dietary supplements are popular among patients with prostate cancer (PC). The objective of this systematic review was to critically examine double-blind, placebo-controlled randomised clinical trials (RCTs) of non-herbal dietary supplements and vitamins (NHDS) for evidence that prostate specific antigen (PSA) levels were reduced in PC patients. Five databases were searched from their inception through December 2012 to identify studies that met our inclusion criteria. Methodological quality was independently assessed by two reviewers using the Cochrane tool. Eight RCTs met the eligibility criteria and were of high methodological quality. The following supplements were tested: isoflavones (genistein, daidzein, and glycitein), minerals (Se) or vitamins (vitamin D) or a combination of antioxidants, bioflavonoids, carotenoids, lycopenes, minerals (Se, Zn, Cu, and Mg), phytoestrogens, phytosterols, vitamins (B2, B6, B9, B12, C, and E), and other substances (CoQ10 and n-acetyl-l cysteine). Five RCTs reported no significant effects compared with placebo. Two RCTs reported that a combination of antioxidants, isoflavones, lycopenes, minerals, plant oestrogens and vitamins significantly decreased PSA levels compared with placebo. One RCT did not report differences in PSA levels between the groups. In conclusion, the hypothesis that dietary supplements are effective treatments for PC patients is not supported by sound clinical evidence. There are promising data for only two specific remedies, which contained a mixture of ingredients, but even for these supplements, additional high quality evidence is necessary before firm recommendations would be justified.
Topics: Acetylcysteine; Antioxidants; Dietary Supplements; Humans; Male; Minerals; Plant Extracts; Prostate-Specific Antigen; Prostatic Neoplasms; Trace Elements; Vitamins
PubMed: 23567264
DOI: 10.1016/j.maturitas.2013.03.006 -
The American Journal of Clinical... Oct 2010To identify associations between polyphenol intake and health and disease outcomes in cohort studies, it is important to identify biomarkers of intake for the various... (Review)
Review
BACKGROUND
To identify associations between polyphenol intake and health and disease outcomes in cohort studies, it is important to identify biomarkers of intake for the various compounds commonly consumed as part of the diet.
OBJECTIVE
The objective of this systematic review was to assess the usefulness of polyphenol metabolites excreted in urine as biomarkers of polyphenol intake in humans.
DESIGN
The method included a structured search strategy for polyphenol intervention studies on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases; formal inclusion and exclusion criteria; data extraction into an Access database; validity assessment; and meta-analysis.
RESULTS
One hundred sixty-two controlled intervention studies with polyphenols were included, and mean recovery yield and correlations with the dose ingested were determined for 40 polyphenols. Polyphenols such as daidzein, genistein, glycitein, enterolactone, and hydroxytyrosol showed both a high recovery yield (12-37%) and a high correlation with the dose (Pearson's correlation coefficients: 0.67-0.87), which showed good sensitivity and robustness as biomarkers of intake throughout the different studies. Weaker recovery for anthocyanins (0.06-0.2%) and weaker correlations with dose [Pearson's correlation coefficients: 0.21-0.52 for hesperidin, naringenin, (-)-epicatechin, (-)-epigallocatechin, quercetin, and 3 microbial metabolites of isoflavones (dihydrodaidzein, equol, and O-desmethylangolensin)] suggest that they are currently less suitable as biomarkers of intake.
CONCLUSIONS
These data confirm the value of certain urinary polyphenols as biomarkers of intake. A validation in populations is now needed to evaluate their specificity, sensitivity, and responsiveness to dose under free-living conditions.
Topics: Anthocyanins; Biomarkers; Eating; Flavanones; Flavonoids; Humans; Phenols; Polyphenols; Review Literature as Topic; Stilbenes
PubMed: 20810980
DOI: 10.3945/ajcn.2010.29924