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Fruit and Vegetable Intake and Mortality: Results From 2 Prospective Cohort Studies of US Men and Women and a Meta-Analysis of 26 Cohort Studies.
Wang, DD, Li, Y, Bhupathiraju, SN, Rosner, BA, Sun, Q, Giovannucci, EL, Rimm, EB, Manson, JE, Willett, WC, Stampfer, MJ, et al
Circulation. 2021;(17):1642-1654
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BACKGROUND The optimal intake levels of fruit and vegetables for maintaining long-term health are uncertain. METHODS We followed 66 719 women from the Nurses' Health Study (1984-2014) and 42 016 men from the Health Professionals Follow-up Study (1986-2014) who were free from cardiovascular disease (CVD), cancer, and diabetes at baseline. Diet was assessed using a validated semiquantitative food frequency questionnaire at baseline and updated every 2 to 4 years. We also conducted a dose-response meta-analysis, including results from our 2 cohorts and 24 other prospective cohort studies. RESULTS We documented 33 898 deaths during the follow-up. After adjustment for known and suspected confounding variables and risk factors, we observed nonlinear inverse associations of fruit and vegetable intake with total mortality and cause-specific mortality attributable to cancer, CVD, and respiratory disease (all Pnonlinear<0.001). Intake of ≈5 servings per day of fruit and vegetables, or 2 servings of fruit and 3 servings of vegetables, was associated with the lowest mortality, and above that level, higher intake was not associated with additional risk reduction. In comparison with the reference level (2 servings/d), daily intake of 5 servings of fruit and vegetables was associated with hazard ratios (95% CI) of 0.87 (0.85-0.90) for total mortality, 0.88 (0.83-0.94) for CVD mortality, 0.90 (0.86-0.95) for cancer mortality, and 0.65 (0.59-0.72) for respiratory disease mortality. The dose-response meta-analysis that included 145 015 deaths accrued in 1 892 885 participants yielded similar results (summary risk ratio of mortality for 5 servings/d=0.87 [95% CI, 0.85-0.88]; Pnonlinear<0.001). Higher intakes of most subgroups of fruits and vegetables were associated with lower mortality, with the exception of starchy vegetables such as peas and corn. Intakes of fruit juices and potatoes were not associated with total and cause-specific mortality. CONCLUSIONS Higher intakes of fruit and vegetables were associated with lower mortality; the risk reduction plateaued at ≈5 servings of fruit and vegetables per day. These findings support current dietary recommendations to increase intake of fruits and vegetables, but not fruit juices and potatoes.
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Beneficial Effects of Time-Restricted Eating on Metabolic Diseases: A Systemic Review and Meta-Analysis.
Moon, S, Kang, J, Kim, SH, Chung, HS, Kim, YJ, Yu, JM, Cho, ST, Oh, CM, Kim, T
Nutrients. 2020;(5)
Abstract
Various behavioral and physiological pathways follow a pre-determined, 24 hour cycle known as the circadian rhythm. Metabolic homeostasis is regulated by the circadian rhythm. Time-restricted eating (TRE) is a type of intermittent fasting based on the circadian rhythm. In this study, we aim to analyze systemically the effects of TRE on body weight, body composition, and other metabolic parameters. We reviewed articles from PubMed, EMBASE, and the Cochrane Library to identify clinical trials that compared TRE to a regular diet. We included 19 studies for meta-analysis. Participants following TRE showed significantly reduced body weight (mean difference (MD), -0.90; 95% confidence interval (CI): -1.71 to -0.10) and fat mass (MD: -1.58, 95% CI: -2.64 to -0.51), while preserving fat-free mass (MD, -0.24; 95% CI: -1.15 to 0.67). TRE also showed beneficial effects on cardiometabolic parameters such as blood pressure (systolic BP, MD, -3.07; 95% CI: -5.76 to -0.37), fasting glucose concentration (MD, -2.96; 95% CI, -5.60 to -0.33), and cholesterol profiles (triglycerides, MD: -11.60, 95% CI: -23.30 to -0.27). In conclusion, TRE is a promising therapeutic strategy for controlling weight and improving metabolic dysfunctions in those who are overweight or obese. Further large-scale clinical trials are needed to confirm these findings and the usefulness of TRE.
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From probiotics to psychobiotics - the gut-brain axis in psychiatric disorders.
Zagórska, A, Marcinkowska, M, Jamrozik, M, Wiśniowska, B, Paśko, P
Beneficial microbes. 2020;(8):717-732
Abstract
This review aims to present a comprehensive state-of-the-art analysis of the bidirectional crosstalk between gut microbiota and the central nervous system (CNS). The literature concerning the potential effects of gut microbiota on psychiatric disorders through neural pathways comprising the 'gut-brain axis' were gathered. In addition, the influence of probiotics and prebiotics and dairy-rich diets combined with the intake of probiotics and prebiotics on gut microbiota and the subsequent relationship with brain function was reviewed. However, a meta-analysis on the effectiveness of probiotic supplementation in psychiatric disorders is lacking. Therefore, a systematic search of PubMed, Embase, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov databases from January 1969 to December 2019 was conducted. It led to the identification of a total of 844 research articles. Of these, a total of 23 studies met the meta-analysis criteria. Statistical analysis revealed that there was no significant difference in the symptoms of schizophrenia, stress, and anxiety between probiotic and placebo groups, post-intervention. Probiotic administration reduced depressive symptoms among patients with depression in a statistically significant manner (standardised mean difference (SMD) = -0.87; 95% confidence interval (95% confidence interval): -1.66, -0.99; P=0.03). Further evidence from larger and more rigorous studies with longer duration of probiotic administration, as well as well-defined populations, homogenous probiotic intervention and outcome measures, are needed to clarify the potential therapeutic effects of probiotics on psychiatric symptoms. Based on the current literature, it seems that not all probiotic-/prebiotic-/dairy-rich diet-based treatments exhibited a psychobiotic effect on the CNS. Among the parameters determining the success of the given treatment, the most significant were probiotic composition (multi-strain formulation), the quantity of ingested psychobiotics and the duration of the study.
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Nonpharmacologic Interventions for Reducing Blood Pressure in Adults With Prehypertension to Established Hypertension.
Fu, J, Liu, Y, Zhang, L, Zhou, L, Li, D, Quan, H, Zhu, L, Hu, F, Li, X, Meng, S, et al
Journal of the American Heart Association. 2020;(19):e016804
Abstract
Background Nonpharmacologic interventions that modify lifestyle can lower blood pressure (BP) and have been assessed in numerous randomized controlled trials and pairwise meta-analyses. It is still unclear which intervention would be most efficacious. Methods and Results Bayesian network meta-analyses were performed to estimate the comparative effectiveness of different interventions for lowering BP. From 60 166 potentially relevant articles, 120 eligible articles (14 923 participants) with a median follow-up of 12 weeks, assessing 22 nonpharmacologic interventions, were included. According to the surface under the cumulative ranking probabilities and Grading of Recommendations Assessment, Development and Evaluation (GRADE) quality of evidence, for adults with prehypertension to established hypertension, high-quality evidence indicated that the Dietary Approach to Stop Hypertension (DASH) was superior to usual care and all other nonpharmacologic interventions in lowering systolic BP (weighted mean difference, 6.97 mm Hg; 95% credible interval, 4.50-9.47) and diastolic BP (weighted mean difference, 3.54 mm Hg; 95% credible interval, 1.80-5.28). Compared with usual care, moderate- to high-quality evidence indicated that aerobic exercise, isometric training, low-sodium and high-potassium salt, comprehensive lifestyle modification, breathing-control, and meditation could lower systolic BP and diastolic BP. For patients with hypertension, moderate- to high-quality evidence suggested that the interventions listed (except comprehensive lifestyle modification) were associated with greater systolic BP and diastolic BP reduction than usual care; salt restriction was also effective in lowering both systolic BP and diastolic BP. Among overweight and obese participants, low-calorie diet and low-calorie diet plus exercise could lower more BP than exercise. Conclusions DASH might be the most effective intervention in lowering BP for adults with prehypertension to established hypertension. Aerobic exercise, isometric training, low-sodium and high-potassium salt, comprehensive lifestyle modification, salt restriction, breathing-control, meditation and low-calorie diet also have obvious effects on BP reduction.
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Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies.
Lassale, C, Batty, GD, Baghdadli, A, Jacka, F, Sánchez-Villegas, A, Kivimäki, M, Akbaraly, T
Molecular psychiatry. 2019;(7):965-986
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With depression being the psychiatric disorder incurring the largest societal costs in developed countries, there is a need to gather evidence on the role of nutrition in depression, to help develop recommendations and guide future psychiatric health care. The aim of this systematic review was to synthesize the link between diet quality, measured using a range of predefined indices, and depressive outcomes. Medline, Embase and PsychInfo were searched up to 31st May 2018 for studies that examined adherence to a healthy diet in relation to depressive symptoms or clinical depression. Where possible, estimates were pooled using random effect meta-analysis with stratification by observational study design and dietary score. A total of 20 longitudinal and 21 cross-sectional studies were included. These studies utilized an array of dietary measures, including: different measures of adherence to the Mediterranean diet, the Healthy Eating Index (HEI) and Alternative HEI (AHEI), the Dietary Approaches to Stop Hypertension, and the Dietary Inflammatory Index. The most compelling evidence was found for the Mediterranean diet and incident depression, with a combined relative risk estimate of highest vs. lowest adherence category from four longitudinal studies of 0.67 (95% CI 0.55-0.82). A lower Dietary Inflammatory Index was also associated with lower depression incidence in four longitudinal studies (relative risk 0.76; 95% CI: 0.63-0.92). There were fewer longitudinal studies using other indices, but they and cross-sectional evidence also suggest an inverse association between healthy diet and depression (e.g., relative risk 0.65; 95% CI 0.50-0.84 for HEI/AHEI). To conclude, adhering to a healthy diet, in particular a traditional Mediterranean diet, or avoiding a pro-inflammatory diet appears to confer some protection against depression in observational studies. This provides a reasonable evidence base to assess the role of dietary interventions to prevent depression. This systematic review was registered in the PROSPERO International Prospective Register of Systematic Reviews under the number CRD42017080579.
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Assessing the impact of diet, exercise and the combination of the two as a treatment for OSA: A systematic review and meta-analysis.
Edwards, BA, Bristow, C, O'Driscoll, DM, Wong, AM, Ghazi, L, Davidson, ZE, Young, A, Truby, H, Haines, TP, Hamilton, GS
Respirology (Carlton, Vic.). 2019;(8):740-751
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This study aimed to provide an updated systematic review and meta-analysis of randomized controlled trials (RCT) investigating the effectiveness of lifestyle interventions on weight loss and the impact on the severity of obstructive sleep apnoea (OSA). A systematic search of five databases between 1980 and May 2018 was used to identify all RCT which employed a lifestyle intervention (i.e. diet-only, exercise-only or combination of the two) aiming to reduce the severity of OSA (assessed using the apnoea-hypopnoea index (AHI)). Random-effects meta-analyses followed by meta-regression were conducted. Ten RCT involving 702 participants (Intervention group: n = 354; Control group: n = 348) were assessed in two meta-analyses. The weighted mean difference in AHI (-8.09 events/h, 95% CI: -11.94 to -4.25) and body mass index (BMI, -2.41 kg/m2 , 95% CI: -4.09 to -0.73) both significantly favoured lifestyle interventions over control arms. Subgroup analyses demonstrated that all interventions were associated with reductions in the AHI, but only the diet-only interventions were associated with a significant reduction in BMI. No association was found between the reduction in AHI or BMI and the length of the intervention, or with baseline AHI and BMI levels. All lifestyle interventions investigated appear effective for improving OSA severity and should be an essential component of treatment for OSA. Future research should be directed towards identifying subgroups likely to reap greater treatment benefits as well as other therapeutic benefits provided by these interventions.
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Impact of different dietary approaches on blood lipid control in patients with type 2 diabetes mellitus: a systematic review and network meta-analysis.
Neuenschwander, M, Hoffmann, G, Schwingshackl, L, Schlesinger, S
European journal of epidemiology. 2019;(9):837-852
Abstract
The aim of this study was to assess the effects of different dietary approaches on low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride (TG) levels in patients with type 2 diabetes (T2D) by applying network meta-analysis (NMA). Systematic electronic and hand searches were conducted until January 2018. Randomized controlled trials (RCTs) with an intervention period of ≥ 12 weeks, focussing on adults with T2D, and comparing dietary approaches regarding LDL, HDL or TGs, were included. For each outcome measure, random effects NMA was performed in order to determine the effect of each dietary approach compared to every other dietary intervention. Mean differences (MDs) and 95% confidence intervals (95% CIs) were calculated, and for the ranking, the surface under the cumulative ranking curves (SUCRA) was determined. Additionally, the credibility of evidence was evaluated. 52 RCTs (44 for LDL, 48 for HDL and 52 for TGs) comparing nine dietary approaches (low fat, vegetarian, Mediterranean, high protein, moderate carbohydrate, low carbohydrate, control, low glycaemic index/glycaemic load and Palaeolithic diet) enrolling 5360 T2D patients were included. The vegetarian diet most effectively reduced LDL levels [MD (95% CI): - 0.33 (- 0.55, - 0.12) mmol/L; compared to the control diet]. The Mediterranean diet beneficially raised HDL [MD (95% CI): 0.09 (0.04, 0.15) mmol/L] and decreased TG levels [MD (95% CI): - 0.41 (- 0.72, - 0.10) mmol/L] compared to the control diet. The Mediterranean diet was the most effective dietary approach to manage diabetic dyslipidaemia altogether (SUCRA 79%). The overall findings are mainly limited by low credibility of evidence.
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Dietary interventions to prevent and manage diabetes in worksite settings: a meta-analysis.
Shrestha, A, Karmacharya, BM, Khudyakov, P, Weber, MB, Spiegelman, D
Journal of occupational health. 2018;(1):31-45
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OBJECTIVES The translation of lifestyle intervention to improve glucose tolerance into the workplace has been rare. The objective of this meta-analysis is to summarize the evidence for the effectiveness of dietary interventions in worksite settings on lowering blood sugar levels. METHODS We searched for studies in PubMed, Embase, Econlit, Ovid, Cochrane, Web of Science, and Cumulative Index to Nursing and Allied Health Literature. Search terms were as follows: (1) Exposure-based: nutrition/diet/dietary intervention/health promotion/primary prevention/health behavior/health education/food /program evaluation; (2) Outcome-based: diabetes/hyperglycemia/glucose/HbA1c/glycated hemoglobin; and (3) Setting-based: workplace/worksite/occupational/industry/job/employee. We manually searched review articles and reference lists of articles identified from 1969 to December 2016. We tested for between-studies heterogeneity and calculated the pooled effect sizes for changes in HbA1c (%) and fasting glucose (mg/dl) using random effect models for meta-analysis in 2016. RESULTS A total of 17 articles out of 1663 initially selected articles were included in the meta-analysis. With a random-effects model, worksite dietary interventions led to a pooled -0.18% (95% CI, -0.29 to -0.06; P<0.001) difference in HbA1c. With the random-effects model, the interventions resulted in 2.60 mg/dl lower fasting glucose with borderline significance (95% CI: -5.27 to 0.08, P=0.06). In the multivariate meta-regression model, the interventions with high percent of female participants and that used the intervention directly delivered to individuals, rather the environment changes, were associated with more effective interventions. CONCLUSION Workplace dietary interventions can improve HbA1c. The effects were larger for the interventions with greater number of female participants and with individual-level interventions.
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Effects of lower versus higher phosphate diets on fibroblast growth factor-23 levels in patients with chronic kidney disease: a systematic review and meta-analysis.
Tsai, WC, Wu, HY, Peng, YS, Hsu, SP, Chiu, YL, Chen, HY, Yang, JY, Ko, MJ, Pai, MF, Tu, YK, et al
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2018;(11):1977-1983
Abstract
BACKGROUND Elevated fibroblast growth factor-23 (FGF23) levels increase the risk of cardiovascular diseases in patients with chronic kidney disease (CKD). We aimed to compare the effects of different dietary interventions, lower versus higher phosphate levels, on FGF23 in patients with CKD. METHODS We conducted electronic literature searches of Medline, PubMed, Embase and the Cochrane Library for publications up to 29 October 2016 for randomized clinical trials that compared lower versus higher phosphate dietary interventions in adults with CKD. The primary outcome was the difference in change-from-baseline FGF23 levels between intervention groups. Considering the difference in measurement units between intact FGF23 and C-terminal FGF23 assays, the treatment effect was analysed as the standardized mean difference (SMD) with the 95% confidence interval (CI). RESULTS We identified five trials enrolling a total of 94 normophosphataemic patients with Stage 3B CKD. The study duration ranged from 1 to 12 weeks. Compared with higher phosphate diets, lower phosphate diets tended to reduce FGF23 levels (SMD -0.74, 95% CI -1.54 to 0.07, P = 0.07). Subgroup analyses showed a trend (P for interaction = 0.09) towards a better FGF23-lowering effect by lower phosphate diets in studies using the intact FGF23 assay (SMD -1.14, 95% CI -2.24 to -0.04) than those using the C-terminal FGF23 assay (SMD -0.05, 95% CI -0.67 to 0.57). CONCLUSIONS Short-term dietary phosphate restriction tends to reduce FGF23 levels in patients with moderately decreased kidney function, and the FGF23-lowering effects tend to be more prominent when measured with the intact FGF23 assay.
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A network meta-analysis on the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus.
Schwingshackl, L, Chaimani, A, Hoffmann, G, Schwedhelm, C, Boeing, H
European journal of epidemiology. 2018;(2):157-170
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The aim of the present study is to assess the comparative efficacy of different dietary approaches on glycaemic control in patients with type 2 diabetes mellitus using a systematic review of the literature. Electronic and hand searches were performed until July 2017. The inclusion criteria were defined as follows: (1) randomized trial with a dietary approach; (2) adults with type 2 diabetes mellitus; (3) outcome either HbA1c (%) and/or fasting glucose (mmol/l); (4) minimum intervention period of 12 weeks. For each outcome measure, random effects network meta-analysis was performed in order to determine the pooled effect of each intervention relative to each of the other interventions. A total of 56 trials comparing nine dietary approaches (low-fat, Vegetarian, Mediterranean, high-protein, moderate-carbohydrate, low-carbohydrate, control, low GI/GL, Palaeolithic) enrolling 4937 participants were included. For reducing HbA1c, the low-carbohydrate diet was ranked as the best dietary approach (SUCRA 84%), followed by the Mediterranean diet (80%) and Palaeolithic diet (76%) compared to a control diet. For reducing fasting glucose, the Mediterranean diet (88%) was ranked as the best approach, followed by Palaeolithic diet (71%) and Vegetarian diet (63%). The network analysis also revealed that all dietary approaches significantly reduce HbA1c (- 0.82 to - 0.47% reduction) and fasting glucose (- 1.61 to - 1.00 mmol/l reduction) compared to a control diet. According to the network meta-analysis the Mediterranean diet is the most effective and efficacious dietary approach to improve glycaemic control in type 2 diabetes patients.