Perspective: NutriGrade: A Scoring System to Assess and Judge the Meta-Evidence of Randomized Controlled Trials and Cohort Studies in Nutrition Research

Egg Consumption and Stroke Risk: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies

Background: The present study was performed to systematically quantify the association between egg consumption and stroke risk as inconsistent results have been produced.

Methods: Three electronic databases (PubMed, Embase, and Cochrane Library), previous reviews, meta-analyses, and bibliographies of relevant articles were retrieved from prospective cohort studies published before July 1, 2020. The random-effects model was employed to estimate summary relative risks (RRs) and 95% confidence intervals (CIs). A dose-response analysis was also performed when data were available.

Results: Sixteen publications involving 24 prospective cohort studies were included in our final meta-analysis. No significant association between egg consumption and stroke risk was identified (RR = 0.92, 95% CI: 0.84–1.01) for the highest vs. the lowest quintiles of egg intake. Subgroup analysis indicated that geographic location significantly modified the effect of egg consumption on stroke risk. Higher egg consumption was attributed to a reduced probability of stroke in Asia (RR = 0.83, 95% CI: 0.73–0.94), but not in North America (RR = 0.95, 95% CI: 0.77–1.16) or Europe (RR = 1.02, 95% CI: 0.91–1.16). Dose-response analysis demonstrated a nearly J-shaped curve between egg consumption and risk of stroke. A decreased risk was observed for the intake of one to four eggs weekly and an increased risk for the intake of more than six eggs weekly. The results were significant at an intake of 10 eggs weekly.

Conclusions: The evidence from this meta-analysis showed that a J-shaped association exists between egg consumption and stroke risk.

Association of Consumption of Sugar-Sweetened Beverages or Artificially Sweetened Beverages with Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

Sugar-sweetened beverage (SSB) and artificially sweetened beverage (ASB) intakes have been reported to be associated with mortality; however, conclusions have been inconsistent. This review synthesized the evidence on the associations of SSB and ASB intakes with mortality from all causes, cardiovascular disease (CVD), and cancer among all populations (including general, diseased, or occupational populations, etc.). PubMed, EMBASE, Web of Science, Cochrane Library, ProQuest, ClinicalTrials.gov, and the International Clinical Trials Registry Platform were searched up to March 2020. Fifteen studies including 17 cohorts were included in meta-analyses. Each serving (12 fluid ounces or 355 mL) increase in daily SSB consumption was associated with higher risks of all-cause (HR: 1.08; 95% CI: 1.04, 1.12; 11 cohorts with 965,851 participants) and CVD (HR: 1.08; 95% CI: 1.04, 1.12; 13 cohorts with 898,005 participants) mortality. The associations of ASB intakes with all-cause and CVD mortality were J-shaped, and HRs (95% CI) across different doses (0, 1, 1.5, 2, and 2.5 servings/d) were 1.00, 1.01 (0.99, 1.03), 1.04 (1.02, 1.07), 1.08 (1.05, 1.11), and 1.13 (1.09, 1.18) for all-cause mortality and 1.00, 1.01 (0.96, 1.07), 1.07 (1.01, 1.13), 1.15 (1.08, 1.23), and 1.25 (1.14, 1.37) for CVD mortality. No significant association was found for cancer mortality. According to the NutriGrade scoring system, the quality of evidence on the associations of SSB intakes with all-cause and CVD mortality was high, and the quality of evidence on other associations was low to moderate. In summary, higher SSB and ASB intakes were associated with higher risks of all-cause mortality and CVD mortality. Given the limited evidence, future studies should further investigate the association between ASB intakes and cause-specific mortality.

Dietary Fiber and Survival in Women with Breast Cancer: A Dose-Response Meta-Analysis of Prospective Cohort Studies

We aimed to investigate the association of dietary fiber consumption with mortality risk in women with breast cancer. A systematic search was undertaken in PubMed, Scopus, and ISI Web of Science till March 2020 to find cohort studies investigating the association of dietary fiber consumption with mortality risk in women with breast cancer. A random-effects model was used to combine study-specific results. The quality of evidence was rated by NutriGrade score. Seven prospective cohort studies with 1,426 cases of all-cause mortality and 679 cases of breast cancer-specific mortality among 11,295 patients with breast cancer were included. The relative risks for the highest compared to the lowest category of dietary fiber consumption were 0.63 (95%CI: 0.52, 0.77; I² = 0%, n = 5) for all-cause mortality, and 0.72 (95%CI: 0.54, 0.96; I² = 0%, n = 5) for breast cancer-specific mortality. There was a strong linear association between fiber intake and all-cause mortality risk. The quality of evidence was rated moderate for all-cause mortality, and low for breast cancer-specific mortality. Higher dietary fiber consumption may improve survival in patients with breast cancer. More research is needed to confirm the present results, considering types of fiber consumed and tumor estrogen receptor status.

An updated systematic review and meta-analysis on adherence to mediterranean diet and risk of cancer

Purpose

The aim of current systematic review was to update the body of evidence on associations between adherence to the Mediterranean diet (MedDiet) and risk of cancer mortality, site-specific cancer in the general population; all-cause, and cancer mortality as well as cancer reoccurrence among cancer survivors.

Methods

A literature search for randomized controlled trials (RCTs), case–control and cohort studies published up to April 2020 was performed using PubMed and Scopus. Study-specific risk estimates for the highest versus lowest adherence to the MedDiet category were pooled using random-effects meta-analyses. Certainty of evidence from cohort studies and RCTs was evaluated using the NutriGrade scoring system.

Results

The updated search revealed 44 studies not identified in the previous review. Altogether, 117 studies including 3,202,496 participants were enclosed for meta-analysis. The highest adherence to MedDiet was inversely associated with cancer mortality (RR_cohort: 0.87, 95% CI 0.82, 0.92; N = 18 studies), all-cause mortality among cancer survivors (RR_cohort: 0.75, 95% CI 0.66, 0.86; N = 8), breast (RR_{observational}: 0.94, 95% CI 0.90, 0.97; N = 23), colorectal (RR_{observational}: 0.83, 95% CI 0.76, 0.90; N = 17), head and neck (RR_{observational}: 0.56, 95% CI 0.44, 0.72; N = 9), respiratory (RR_cohort: 0.84, 95% CI 0.76, 0.94; N = 5), gastric (RR_{observational}: 0.70, 95% CI 0.61, 0.80; N = 7), bladder (RR_{observational}: 0.87, 95% CI 0.76, 0.98; N = 4), and liver cancer (RR_{observational}: 0.64, 95% CI 0.54, 0.75; N = 4). Adhering to MedDiet did not modify risk of blood, esophageal, pancreatic and prostate cancer risk.

Conclusion

In conclusion, our results suggest that highest adherence to the MedDiet was related to lower risk of cancer mortality in the general population, and all-cause mortality among cancer survivors as well as colorectal, head and neck, respiratory, gastric, liver and bladder cancer risks. Moderate certainty of evidence from cohort studies suggest an inverse association for cancer mortality and colorectal cancer, but most of the comparisons were rated as low or very low certainty of evidence.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02346-6) contains supplementary material, which is available to authorized users.

Healthy and unhealthy dietary patterns and the risk of chronic disease: an umbrella review of meta-analyses of prospective cohort studies

We aimed to fully review the association of empirical dietary patterns with the risk of non-communicable chronic diseases and to rate the quality of the evidence. Published meta-analyses of observational studies investigating the association of empirically derived dietary patterns with the risk of chronic diseases were identified by searching PubMed and Scopus till September 2019. Two independent reviewers extracted the information and rated the quality of the evidence by NutriGrade score. For each meta-analysis, cross-sectional and case–control studies were excluded and then summary relative risk was recalculated by using a random-effects model. Sixteen meta-analyses of prospective cohort studies, reporting eighteen SRR for healthy dietary patterns and sixteen SRR for unhealthy patterns obtained from 116 primary prospective cohort studies with 4·8 million participants, were included. There was moderate quality of evidence for the inverse association of healthy dietary patterns with the risk of type 2 diabetes (T2D), fracture and colorectal and breast cancers. There was also low-quality evidence for the inverse relation between healthy dietary patterns and the risk of all-cause and cardiovascular mortality, depression, CHD and respiratory diseases. There was moderate quality of evidence for a positive association between unhealthy dietary patterns and the risk of T2D, fracture and the metabolic syndrome. Adopting a healthy dietary pattern may reduce the risk of T2D, CHD and premature death. More research is needed for outcomes for which the quality of the evidence was rated low, such as respiratory disease, mental illness and site-specific cancers.

The Nordic Nutrition Recommendations 2022 - structure and rationale of qualified systematic reviews

BACKGROUND

Qualified systematic reviews (SRs) will form the main basis for evaluating causal effects of nutrients or food groups on health outcomes in the sixth edition of Nordic Nutrition Recommendations to be published in 2022 (NNR2022).

OBJECTIVE

To describe rationale and structure of SRs used in NNR2022.

DESIGN

The SR methodologies of the previous edition of NNR were used as a starting point. Methodologies of recent SRs commissioned by leading national food and health authorities or international food and health organizations were examined and scrutinized. Methodologies for developing SRs were agreed by the NNR2022 Committee in a consensus-driven process.

RESULTS

Qualified SRs will be developed by a cross-disciplinary group of experts and reported according to the requirements of the EQUATOR network. A number of additional requirements must also be fulfilled, including 1) a clearly stated set of objectives and research questions with pre-defined eligibility criteria for the studies, 2) an explicit, reproducible methodology, 3) a systematic search that attempts to identify all studies that would meet the eligibility criteria, 4) an assessment of the validity of the findings of the included studies through an assessment of 'risk of bias' of the studies, 5) a systematic presentation and synthesis of the characteristics and findings of the included studies, and 6) a grading of the overall evidence. The complete definition and requirements of a qualified SR are described.

DISCUSSION

Most SRs published in scientific journals do not fulfill all criteria of the qualified SRs in the NNR2022 project. This article discusses the structure and rationale for requirements of qualified SRs in NNR2022. National food and health authorities have only recently begun to use qualified SRs as a basis for nutrition recommendations.

CONCLUSION

Qualified SRs will be used to inform dietary reference values (DRVs) and food-based dietary guidelines (FBDGs) in the NNR2022 project.

Effect of dietary anthocyanins on biomarkers of glycemic control and glucose metabolism: A systematic review and meta-analysis of randomized clinical trials

Anthocyanins, as natural food colorants, are bioactive substances with several health advantages. In this research, the effects of dietary anthocyanins on biomarkers of glycemic control and glucose metabolism was evaluated through a meta-analysis. The results revealed a significant reduction in levels of fasting blood sugar (FBS; -2.70 mg/dl, 95% CI: -4.70 to -1.31; P < 0.001), 2-h postprandial glucose (2-h PPG; -11.1 mg/dl, 95% CI: -18.7 to -3.48; P = 0.004), glycated hemoglobin (HbA1c; -11.1 mg/dl, 95% CI: -18.7 to -3.48; P = 0.004), homeostasis model assessment of insulin resistance (HOMA-IR; -0.54, 95% CI: -0.94 to -0.14; P = 0.008), resistin (-1.23 µg/l, 95% CI: -2.40 to -0.05; P = 0.041), and plasminogen activator inhibitor-1 (PAI-1; -5.09 µg/l, 95% CI: -9.45 to -0.73; P = 0.022) following administration of anthocyanins, whilst changes in the levels of fasting insulin (0.33 mU/l, 95% CI: -0.18 to 0.85; P = 0.207) and C-peptide (-0.02 µg/l, 95 %CI: -0.20 to 0.16; P = 0.816) was not statistically significant. Consumption of anthocyanins for >8 weeks and at doses >300 mg/day significantly reduced levels of FBS, 2-h PPG, HbA1c, and HOMA-IR. Moreover, anthocyanins administration reduced the levels of FBS, 2-h PPG, HbA1c, and HOMA-IR in type 2 diabetic subjects and HOMA-IR in overweight/obese individuals. Overall, dietary anthocyanins can be used as an adjuvant therapy to improve biomarkers of glycemic control and glucose metabolism specially in diabetic subjects.

Use of the GRADE approach in health policymaking and evaluation: a scoping review of nutrition and physical activity policies

BACKGROUND

Nutrition and physical activity policies have the potential to influence lifestyle patterns and reduce the burden of non-communicable diseases. In the world of health-related guidelines, GRADE (Grading of Recommendations, Assessment, Development and Evaluation) is the most widely used approach for assessing the certainty of evidence and determining the strength of recommendations. Thus, it is relevant to explore its usefulness also in the process of nutrition and physical activity policymaking and evaluation. The purpose of this scoping review was (i) to generate an exemplary overview of documents using the GRADE approach in the process of nutrition and physical activity policymaking and evaluation, (ii) to find out how the GRADE approach has been applied, and (iii) to explore which facilitators of and barriers to the use of GRADE have been described on the basis of the identified documents. The overarching aim of this work is to work towards improving the process of evidence-informed policymaking in the areas of dietary behavior, physical activity, and sedentary behavior.

METHODS

A scoping review was conducted according to current reporting standards. MEDLINE via Ovid, the Cochrane Library, and Web of Science were systematically searched up until 4 July 2019. Documents describing a body of evidence which was assessed for the development or evaluation of a policy, including documents labeled as "guidelines," or systematic reviews used to inform policymaking were included.

RESULTS

Thirty-six documents were included. Overall, 313 GRADE certainty of evidence ratings were identified in systematic reviews and guidelines; the strength of recommendations/policies was assessed in four documents, and six documents mentioned facilitators or barriers for the use of GRADE. The major reported barrier was the initial low starting level of a body of evidence from non-randomized studies when assessing the certainty of evidence.

CONCLUSION

This scoping review found that the GRADE approach has been used for policy evaluations, in the evaluation of the effectiveness of policy-relevant interventions (policymaking), as well as in the development of guidelines intended to guide policymaking. Several areas for future research were identified to explore the use of GRADE in health policymaking and evaluation.

The effect of vitamin D supplementation on insulin-like growth factor-1: A systematic review and meta-analysis of randomized controlled trials

PURPOSE

There is equivocality regarding the interaction between vitamin D and insulin-like growth factor-1 (IGF-1). Thus, the aim of this study was to elucidate the effect of vitamin D supplementation on serum levels of IGF-1 by conducting a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

PubMed, Scopus, and ISI Web of Science databases were searched up to May 2019 for RCTs that evaluated the effect of vitamin D supplementation on IGF-1 levels. Mean and standard deviation changes of IGF-1 in each treatment group were considered for analysis and pooled using random-effect model. Risk of bias for included studies was assessed by the Cochrane scale and the NutriGrade approach was applied to evaluate the quality of evidence.

RESULTS

Six trials (n = 773 participants) were included in the meta-analysis. Compared with control group, vitamin D supplementation yielded no significant effect on serum level of IGF-1 (weighted mean difference [WMD] =4.66 ng/ml, 95 % CIs: -6.72 to 16.03, P = 0.42, I² = 74.8, P_{-heterogeneity} = 0.001). Additionally, no meaningful changes were observed in subgroup analyses.

CONCLUSION

The evidence from the limited number of published trials does not convincingly show that vitamin D supplementation elicits any clinically relevant effects on IGF-1 levels. More high-quality studies are needed to reach a consensual conclusion in this area.

Dietary Factors and Neurodegenerative Disorders: An Umbrella Review of Meta-Analyses of Prospective Studies

Diet has been hypothesized to be associated with neurodegenerative disorders. The aim was to conduct an umbrella review to summarize and evaluate the current evidence of prospective associations between any dietary factors and the incidence of neurodegenerative disorders. We conducted a systematic search in PubMed, Embase, and the Cochrane library up to November 2019 to identify systematic reviews with meta-analyses of prospective studies investigating the association between dietary factors (dietary patterns, foods and beverages, nutrients, and phytochemicals) and neurodegenerative disorders (cognitive decline, cognitive impairment, Alzheimer disease, all-cause dementia, and Parkinson disease). Summary risk ratios (SRRs) and 95% CIs were recalculated using a random effects model. We evaluated the risk of bias of identified meta-analyses and the quality of evidence for all associations. In total, 20 meta-analyses including 98 SRRs were identified. All original meta-analyses were rated as being at high risk of bias. Methodological concerns related mainly to the inappropriate synthesis, assessment, and discussion of the risk of bias of primary studies. For the recalculated meta-analyses, quality of evidence was moderate for inverse associations between higher adherence to the Mediterranean diet (SRR: 0.63; 95% CI: 0.48, 0.82; n = 4 primary studies) and higher fish intake (SRR: 0.72; 95% CI: 0.59, 0.89; n = 6) and Alzheimer disease, as well as for tea consumption and all-cause dementia (SRR: 0.74; 95% CI: 0.63, 0.88; n = 2) and Parkinson disease (SRR per 2 cups/d: 0.69; 95% CI: 0.54, 0.87; n = 5). This umbrella review provides a comprehensive overview of the available evidence on dietary factors and neurodegenerative disorders. The results indicate that the Mediterranean diet, fish, and tea could be inversely associated with neurodegenerative disorders. However, the quality of evidence was generally low, suggesting that further studies are likely to change the overall estimates. Thus, more well-conducted research, also investigating other dietary factors in association with neurodegenerative disorders, is warranted.

Fish consumption and the risk of cardiovascular disease and mortality in patients with type 2 diabetes: a dose-response meta-analysis of prospective cohort studies

We aimed to investigate the association of fish consumption with the risk of coronary heart disease (CHD), stroke and all-cause mortality in patients with type 2 diabetes (T2D). We systematically searched PubMed and Scopus from inception till June 2019. We included prospective cohort studies assessing the relation of fish intake with the risk of CHD, stroke and mortality in patients with T2D. Study-specific results were pooled with the use of a random-effects model. Nine prospective cohort studies with 57,394 diabetic patients were identified. The relative risks for the highest compared with the lowest category of fish consumption were 0.86 (95% CI 0.76, 0.96; I² = 50%, n = 8) for all-cause mortality, and 0.61 (95% CI 0.29, 0.93; I² = 68%, n = 3) for CHD. There was a monotonic inverse association, with a nadir at fish consumption of approximately 2-3 servings/week, in both analyses. A nonsignificant inverse association was found for stroke. In the analysis of all-cause mortality, a nonsignificant inverse association was found in studies that controlled for energy intake, suggesting that the observed inverse association was not an addition effect, but may be due to substituting other foods such as red and processed meat with fish.

A systematic review and meta-analysis of the association between fish consumption and risk of metabolic syndrome

AIMS

Results regarding the association between fish intake and risk of metabolic syndrome (MetS) are ambiguous. Therefore, this study aims to evaluate whether there is an association between fish consumption and risk of MetS.

DATA SYNTHESIS

A comprehensive literature search was conducted of PubMed, Embase, ScienceDirect and Google Scholar up to August 2019. A random-effects model was used to pool the risk of MetS in the highest category of fish consumption compared with the lowest one. Subgroup analysis was conducted based on country of region, gender, dietary tool, MetS definition, energy adjustment and sample size. A dose-response of analysis of fish intake and risk of MetS was also conducted. Twelve studies with a total of 16 effect sizes (10 cross-sectional and six cohort) were included. An inverse association was observed between fish intake and risk of MetS in cohort (OR = 0.80, 95% CI: 0.66, 0.96; P = 0.017, I² = 62.9%) but not cross-sectional studies (OR = 0.80, 95% CI: 0.70, 1.02; P = 0.085, I² = 50.1%). Subgroup analysis suggested that the results were influenced by all the included variables but sample size. A significant non-linear association was observed between fish intake levels and risk of MetS (P-value for non-linearity = 0.010).

CONCLUSION

An inverse association existed between fish intake and risk of MetS when combining data from prospective cohort studies. Further studies are needed to confirm such an effect.

Adherence to the dietary approaches to stop hypertension (DASH) diet in relation to all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective cohort studies

Background

Although previous investigations have proposed an association between Dietary Approaches to Stop Hypertension (DASH)-style diet and lower mortality from chronic diseases, the exposure-response relationship is not clear. The present systematic review and meta-analysis aimed to explore the linear and non-linear dose-response association between adherence to the DASH diet and all-cause and cause-specific mortality.

Methods

Database search was performed in PubMed, Scopus, and EMBASE for prospective cohort studies investigating the association between adherence to the Dietary Approaches to Stop Hypertension (DASH) diet and risk of mortality. Summary hazard ratios (HRs) and 95% confidence intervals (CI) were estimated with the use of a random-effects model for the linear and nonlinear relationships. The two-stage hierarchical regression model was applied to test the potential non-linear dose-response associations.

Results

The inclusion criteria were met by 17 studies (13 publications). The scores reported for adherence to the DASH diet in different studies were converted to a conventional scoring method in which the adherence score might range between 8 to 40. The linear analysis revealed that summary HRs were 0.95 (95% CI: 0.94–0.96, I² = 91.6%, n = 14) for all-cause, 0.96 (95% CI: 0.95–0.98, I² = 82.4%, n = 12) for CVD, 0.97 (95% CI: 0.96–0.98, I² = 0.00%, n = 2) for stroke, and 0.97 (95% CI: 0.95–0.98, I² = 63.7%, n = 12) for cancer mortality per each 5-point increment of adherence to the DASH diet. There was also evidence of non-linear associations between the DASH diet and all-cause and cause-specific mortality as the associations became even more evident when the adherence scores were more than 20 points (P < 0.005).

Conclusion

Even the modest adherence to the DASH diet is associated with a lower risk of all-cause and cause-specific mortality. The higher adherence to the diet also strengthens the risk-reducing association.

Registration

This review was registered in the international prospective register of systematic reviews (PROSPERO) database (registration ID: CRD42018086500).

Fish Consumption and the Risk of Chronic Disease: An Umbrella Review of Meta-Analyses of Prospective Cohort Studies

We aimed to present a comprehensive review of published meta-analyses of prospective cohort studies on the association of fish consumption and the risk of chronic disease. A systematic search was undertaken in Pubmed and Scopus to October 2019 to find meta-analyses of observational studies evaluating the association of fish consumption and the risk of chronic disease. Retrospective and cross-sectional studies and studies with unadjusted risk estimates were excluded. The summary relative risk (SRR) for each meta-analysis was recalculated by using a random-effects model. The methodological quality of included meta-analyses and the quality of the evidence were assessed by the AMSTAR and NutriGrade tools, respectively. A total of 34 meta-analyses of prospective observational studies, reporting SRRs for 40 different outcomes obtained from 298 primary prospective cohort studies, were included. Moderate-quality evidence suggested that each 100-g/d increment in fish consumption was associated with a lower risk of all-cause mortality (SRR: 0.92; 95% CI: 0.87, 0.97), cardiovascular mortality (SRR: 0.75; 95% CI: 0.65, 0.87), coronary heart disease (SRR: 0.88; 95% CI: 0.79, 0.99), myocardial infarction (SRR: 0.75; 95% CI: 0.65, 0.93), stroke (SRR: 0.86; 95% CI: 0.75, 0.99), heart failure (SRR: 0.80; 95% CI: 0.67, 0.95), depression (SRR: 0.88; 95% CI: 0.79, 0.98), and liver cancer (SRR: 0.65; 95% CI: 0.48, 0.87). For cancers of most sites, there was no significant association and the quality of the evidence was rated low and very low. In conclusion, evidence of moderate quality suggests that fish consumption is associated with a lower risk of cardiovascular disease, depression, and mortality and, therefore, can be considered as a healthy animal-based dietary source of protein. Further research is needed for outcomes for which the quality of the evidence was rated low and very low, considering types of fish consumed, different methods of cooking fish, and all potential confounding variables.

Adherence to healthy dietary pattern and risk of kidney disease: a systematic review and meta-analysis of observational studies

Epidemiological studies show that adherence to healthy dietary patterns may be associated with a lower risk of decline in kidney function. However, existing evidence has not been quantitatively gathered. Pertinent observational studies investigating the association of adherence to a healthy dietary pattern, either priori-defined dietary pattern/indices or data-driven dietary patterns, with risk of kidney disease in the general population were identified by searching Medline and Scopus databases to May 28, 2018. A random-effects meta-analysis was applied. The analysis included eight prospective cohorts (5734 cases among 569,688 participants) and five cross-sectional studies (1955 cases among 16,614 participants). Higher adherence to a healthy dietary pattern (either priori-defined or data-driven dietary patterns) was associated with a 28% lower risk of kidney disease in the analysis of prospective cohort studies (RR = 0.72, 95 % CI = 0.58, 0.86; I² = %71, n = 8). A subgroup analysis based on definition of healthy dietary pattern resulted in significant inverse association only in the subgroup of Dietary Approaches to Stop Hypertension dietary pattern (RR: 0.74, 95 % CI: 0.54, 0.93; I² = 73%, n = 5). A dose-response analysis indicated a monotonic inverse association between adherence to the Dietary Approaches to Stop Hypertension dietary pattern with risk of kidney disease. A 32% lower risk was observed in the analysis of cross-sectional studies (OR: 0.68, 95 %CI: 0.53, 0.83, I² = 0%, n = 5). The findings suggest that higher adherence to a healthy dietary pattern is associated with a lower risk of kidney disease.

Effect of Egg Consumption on Blood Pressure: a Systematic Review and Meta-analysis of Randomized Clinical Trials

PURPOSE OF REVIEW

We identified and quantified the results of randomized controlled trials (RCTs) that have assessed the impact of egg consumption on blood pressure in adults.

RECENT FINDINGS

We conducted a comprehensive search of medical bibliographic databases up to February 2019 for RCTs investigating the effect of egg consumption on blood pressure in adults. Fifteen RCTs were included with a total of 748 participants. Overall, egg consumption had no significant effect on systolic blood pressure (weighted mean difference (WMD) = 0.046 mmHg; 95% CI - 0.792, 0.884) and diastolic blood pressure (WMD = - 0.603 mmHg; 95% CI - 1.521, 0.315). Subgroup analyses had no effect on pooled results and no heterogeneity was found among included studies. Egg consumption has no significant effects on systolic and diastolic blood pressure in adults. Due to several limitations among existing studies, general conclusions cannot be drawn regarding the beneficial or neutral impact of egg consumption on blood pressure in adults.

Alpha-lipoic acid effect on leptin and adiponectin concentrations: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

New evidence suggests that dysregulation of adipocytokines caused by excess adiposity plays an important role in the pathogenesis of various obesity comorbidities. Our aim in this meta-analysis was to determine the effect of alpha-lipoic acid (ALA) supplementation on serum levels of leptin and adiponectin.

METHODS

We searched Scopus, PubMed, Google Scholar, and ISI Web of Science from inception up to July 2019. Mean difference for leptin and adiponectin were calculated by subtracting the change from baseline in each study group. Summary estimates for the overall effect of ALA on serum leptin and adiponectin concentrations were calculated using random effects model. Results were presented as weighted mean difference (WMD) and their 95% confidence intervals (CI). Between-study heterogeneity was examined using the I² statistics.

RESULT

Eight studies were included in systematic review and seven studies in meta-analysis. The overall effect suggested a significant decrement in serum leptin concentrations (WMD = - 3.63; 95% CI, - 5.63, - 1.64 μg/ml; I² = 80.7%) and a significant increase in serum levels of adiponectin (WMD = 1.98 μg/ml; 95% CI, 0.92, 3.04; I² = 95.7%). Subgroup analyses based on age showed a significant reduction in leptin levels only in younger adults, and subgroup analysis based on duration indicated in studies with a duration of more than 8 weeks adiponectin levels increased significantly and leptin levels decreased significantly.

CONCLUSION

Our results revealed ALA decreased leptin and increased adiponectin especially in studies lasted more than 8 weeks. We still need more studies with different ALA dose, intervention duration, and separately on male and female.

Effects of respiratory muscle therapy on obstructive sleep apnea: a systematic review and meta-analysis

STUDY OBJECTIVES

The purpose of this study is to conduct a systematic review and meta-analysis evaluating the effects of respiratory muscle therapy (ie, oropharyngeal exercises, speech therapy, breathing exercises, wind musical instruments) compared with control therapy or no treatment in improving apnea-hypopnea index ([AHI] primary outcome), sleepiness, and other polysomnographic outcomes for patients diagnosed with obstructive sleep apnea (OSA).

METHODS

Only randomized controlled trials with a placebo therapy or no treatment searched using PubMed, EMBASE, Cochrane, and Web of Science up to November 2018 were included, and assessment of risk of bias was completed using the Cochrane Handbook.

RESULTS

Nine studies with 394 adults and children diagnosed with mild to severe OSA were included, all assessed at high risk of bias. Eight of the 9 studies measured AHI and showed a weighted average overall AHI improvement of 39.5% versus baselines after respiratory muscle therapy. Based on our meta-analyses in adult studies, respiratory muscle therapy yielded an improvement in AHI of -7.6 events/h (95% confidence interval [CI] = -11.7 to -3.5; P ≤ .001), apnea index of -4.2 events/h (95% CI = -7.7 to -0.8; P ≤ .016), Epworth Sleepiness Scale of -2.5 of 24 (95% CI= -5.1 to -0.1; P ≤ .066), Pittsburgh Sleep Quality Index of -1.3 of 21 (95% CI= -2.4 to -0.2; P ≤ .026), snoring frequency (P = .044) in intervention groups compared with controls.

CONCLUSIONS

This systematic review highlights respiratory muscle therapy as an adjunct management for OSA but further studies are needed due to limitations including the nature and small number of studies, heterogeneity of the interventions, and high risk of bias with low quality of evidence.

Red and Processed Meats and Health Risks: How Strong Is the Evidence?

Prevailing dietary guidelines have widely recommended diets relatively low in red and processed meats and high in minimally processed plant foods for the prevention of chronic diseases. However, an ad hoc research group called the Nutritional Recommendations (NutriRECS) consortium recently issued "new dietary guidelines" encouraging individuals to continue their current meat consumption habits due to "low certainty" of the evidence, difficulty of altering meat eaters' habits and preferences, and the lack of need to consider environmental impacts of red meat consumption. These recommendations are not justified, in large part because of the flawed methodologies used to review and grade nutritional evidence. The evidence evaluation was largely based on the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) criteria, which are primarily designed to grade the strength of evidence for clinical interventions especially pharmacotherapy. However, the infeasibility for conducting large, long-term randomized clinical trials on most dietary, lifestyle, and environmental exposures makes the criteria inappropriate in these areas. A separate research group proposed a modified and validated system for rating the meta-evidence on nutritional studies (NutriGRADE) to address several limitations of the GRADE criteria. Applying NutriGRADE, the evidence on the positive association between red and processed meats and type 2 diabetes was rated to be of "high quality," while the evidence on the association between red and processed meats and mortality was rated to be of "moderate quality." Another important limitation is that inadequate attention was paid to what might be replacing red meat, be it plant-based proteins, refined carbohydrates, or other foods. In summary, the red/processed meat recommendations by NutriRECS suffer from important methodological limitations and involve misinterpretations of nutritional evidence. To improve human and planetary health, dietary guidelines should continue to emphasize dietary patterns low in red and processed meats and high in minimally processed plant foods such as fruits and vegetables, whole grains, nuts, and legumes.

Use of platelet-rich plasma, platelet-rich growth factor with arthrocentesis or arthroscopy to treat temporomandibular joint osteoarthritis: Systematic review with meta-analyses

BACKGROUND

The authors conducted a systematic review and meta-analysis to determine whether arthrocentesis or arthroscopy combined with platelet-rich plasma (PRP) or platelet-rich growth factor (PRGF) injection compared with no injection or saline injection (control group) or hyaluronic acid (HA) injection reduced pain and increased maximum mouth opening (MMO) in patients with temporomandibular joint (TMJ) osteoarthritis (OA).

TYPES OF STUDIES REVIEWED

The authors used the Cochrane Library, Embase, PubMed, Web of Science, Google Scholar databases and hand searched reference lists through May 4, 2018, to identify randomized controlled trials and controlled trials including patients with TMJ OA receiving injections (PRP or PRGF versus other). The authors assessed the risk of bias according to the Cochrane guidelines.

RESULTS

The authors screened 36 abstracts. They included 5 studies (3 randomized controlled trials and 2 controlled trials) with a total of 285 patients with TMJ OA in this review. The authors assessed all 5 studies as being at high risk of bias. The quality of evidence was very low owing to statistical heterogeneity, small sample size, or high risk of bias. Meta-analyses with 2 studies showed a visual analog scale pain improvement from baseline of -2.778 units (0-10 scale, 0 = no pain, 10 = worst pain) favorable to PRP or PRGF compared with findings in control groups (95% confidence interval [CI], -3.504 to -2.052; P < .001) and an improvement of -0.968 favorable to PRP or PRGF compared with findings in HA groups (95% CI, -1.854 to -0.082; P = .032). The authors found no significant increase in MMO in those receiving PRP or PRGF compared with that in the control or HA groups.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Although the results of the included studies showed that arthrocentesis or arthroscopy with PRP or PRGF, saline, or HA injections all reduced pain and increased mouth opening, the evidence was of very low quality. Further studies are needed to confirm these preliminary results showing that PRP or PRGF with arthrocentesis or arthroscopy significantly improved pain but did not increase MMO compared with findings in the control or HA groups.

Impact of dietary anthocyanins on systemic and vascular inflammation: Systematic review and meta-analysis on randomised clinical trials

Anthocyanins are natural bioactive compounds that have several health benefits. This systematic review and meta-analysis assessed the impact of dietary anthocyanins on markers of systemic and vascular inflammation. Meta-analysis of 32 randomised controlled trials indicated that dietary anthocyanins significantly decreased levels of C-reactive protein (CRP; -0.33 mg/l, 95% CI: -0.55 to -0.11, P = 0.003), interleukin-6 (IL-6; -0.41 ρg/ml, 95% CI: -0.70 to -0.13, P = 0.004), tumor necrosis factor-alpha (TNF-α; -0.64 ρg/ml, 95% CI: -1.18 to -0.09, P = 0.023), intercellular adhesion molecule-1 (-52.4 ng/ml, 95% CI: -85.7 to -19.1, P = 0.002), and vascular adhesion molecule-1 (VCAM-1; -49.6 ng/ml, 95% CI: -72.7 to -26.5, P < 0.001) while adiponectin level was significantly increased (0.75 μg/ml, 95% CI: 0.23 to 1.26, P = 0.004). The levels of interleukin-1β (IL-1β; -0.45 ρg/ml, 95% CI: -3.77 to 2.88, P = 0.793) and P-selectin (-6.98 ng/ml, 95% CI: -18.1 to 4.15, P = 0.219) did not significantly change. Subgroup analyses showed that administration of higher doses of anthocyanins (>300 mg/day) significantly decreased levels of CRP, IL-6, TNF-α, and VCAM-1. The results indicate that dietary anthocyanins reduce the levels of systemic and vascular inflammation in the subjects.

Effects of pycnogenol on cardiometabolic health: A systematic review and meta-analysis of randomized controlled trials

AIM

Clinical trials on the effect of pycnogenol supplementation on cardiometabolic health have been controversial. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the potential effect of pycnogenol supplementation on cardiometabolic profile.

METHODS

PubMed, Scopus, and ISI Web of Science databases were searched until October 2018. RCTs that evaluated the effects of pycnogenol on cardiometabolic parameters were included. DerSimonian and Laird random-effect models were used to compute the weighted mean differences (WMDs) and 95% confidence intervals (CIs).

RESULTS

Twenty-four RCTs including 1594 participants were included in the meta-analysis. Pycnogenol significantly reduced fasting blood glucose (WMD: -5.86 mg/dl; 95% CI: -9.56, -2.15), glycated hemoglobin (WMD = -0.29%, 95%CI: -0.56, -0.01), systolic blood pressure (WMD: -2.54 mmhg; 95% CI: -4.08, -0.99), diastolic blood pressure (WMD: -1.76 mmhg; 95% CI: -3.12, -0.41), body mass index (WMD: -0.47 kg/m²; 95% CI: -0.90, -0.03), LDL cholesterol (WMD: -7.12 mg/dl; 95% CI: -13.66, -0.58) and increased HDL cholesterol (WMD: 3.27 mg/dl; 95% CI: 0.87, 5.66).

CONCLUSION

This meta-analysis suggests that pycnogenol may have a role in preventing cardiometabolic disease. However, further well-designed RCTs are recommended to evaluate its long-term effects and explore the optimal duration of use and dosage.

Perspective: Network Meta-analysis Reaches Nutrition Research: Current Status, Scientific Concepts, and Future Directions

Traditional pairwise meta-analysis (PMA) is a very useful method that pools evidence from one study design type if appropriate; its widespread use in nutrition research is an important phenomenon. Recently, a promising method for more advanced evidence-synthesis, called network meta-analysis (NMA), was introduced. NMA is an extension of PMA that enables simultaneous comparison of multiple interventions. NMA combines direct evidence (i.e., trials comparing 2 interventions directly) and indirect evidence (i.e., from a connected route via ≥1 comparators, e.g. placebo) in a network of studies. NMAs have the potential to advance knowledge in the field of nutrition as they provide insights that cannot be obtained by individual 2-arm randomized controlled trials or PMA. Thus, in this perspective paper, we aim to summarize the current (methodologic) status of published NMAs in nutrition research and emphasize advances and strengths in comparison with traditional PMA through specific examples, and highlight potential pitfalls and limitations. NMA is an emerging methodology in the field of nutrition research. A PubMed search identified only 23 nutrition research-related NMAs published since the inception of journals up to January 8, 2019 (61% of them published since 2017), compared with >5000 published PMAs. Moreover, we aim to highlight the scientific concepts and standards through the use of the following NMA example: "Which type of oils/solid fats offers the greatest impact on blood lipids?" In this regard, we discuss intervention definitions, transitivity/similarity, statistical methods, description and visualization of results, inconsistency, ranking, dissemination bias, assessing the certainty of evidence by Grading of Recommendations Assessment, Development and Evaluation, and reporting guidelines. We expect that rigorously conducted NMAs based on high-quality systematic reviews will become the new evidence synthesis benchmark in nutrition research. However, caution is warranted because abuse and misinterpretations of PMA and NMA findings could hamper the scientific field and possibly decision-making regarding public policy.

Evidence Collection and Evaluation for the Development of Dietary Guidelines and Public Policy on Nutrition

Dietary guidelines and recommendations, usually developed by government bodies or large authoritative organizations, have major downstream effects on public policy. A growing body of evidence supports the notion that there are serious deficiencies in the methods used to develop dietary guidelines. Such deficiencies include the failure to access or conduct comprehensive systematic reviews, a lack of systematic or rigorous evaluation of the quality of the evidence, a failure to acknowledge the limitations of the evidence base underlying recommendations, and insufficiently stringent management of conflicts of interest. These issues may be addressed by adhering to international standards for guideline development, including adopting systematic review methodology and using rigorous systems to evaluate the certainty of the evidence and to move from evidence to recommendations, of which the GRADE approach (Grading of Recommendations Assessment,Development and Evaluation) is the most rigorous and fully developed. Improving the methods by which dietary guidelines are produced has considerable potential to substantially improve public policy decision-making.

Does L-carnitine supplementation affect serum levels of enzymes mainly produced by liver? A systematic review and meta-analysis of randomized controlled clinical trials

BACKGROUND AND AIMS

L-carnitine supplementation is proposed to reduce liver enzymes levels; however, previous findings were equivocal. The current systematic review and meta-analysis of randomized controlled clinical trials (RCTs) were performed to assess the effect of L-carnitine supplementation on serum levels of enzymes mainly produced by liver [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGTP)].

METHODS

Online databases as well as the reference lists of relevant studies were searched from inception up to June 2019. The risk of bias in individual studies was assessed using Cochrane Collaboration's tool. Data were pooled using the random-effects model and expressed as mean differences (MDs) with 95% confidence intervals (CIs).

RESULTS

In total, 18 RCTs (1161 participants) met the eligibility criteria. L-carnitine supplementation dose ranged from 500 to 4000 mg/day. L-carnitine supplementation significantly reduced serum ALT (MD = - 8.65 IU/L, 95% CI - 13.40, - 3.90), AST (MD = - 8.52 IU/L, 95% CI - 12.16, - 4.89), and GGTP (MD = - 8.80 IU/L, 95% CI - 13.67, - 3.92) levels. The subgroup analysis showed that L-carnitine might be more effective in reducing the enzymes when supplemented in higher doses (≥ 2000 mg/day), for longer durations (> 12 weeks), and among patients with liver diseases. The meta-evidence was graded as "moderate" for ALT and AST, and "low" for GGTP according to NutriGrade scoring system.

CONCLUSION

L-carnitine supplementation significantly improves circulating ALT, AST and GGTP levels; therefore, it might positively affect liver function, especially among patients with liver diseases. Further high-quality RCTs are recommended to confirm our results.

The effect of vitamin D supplementation on the androgenic profile in men: A systematic review and meta-analysis of clinical trials

The aim of this systematic review and meta-analysis was to evaluate the effect of vitamin D supplementation on total testosterone (TT) and sex hormone-binding globulin (SHBG) in men. We searched PubMed, Scopus and Web of Science for randomized, controlled trials of vitamin D supplementation in men ≥18 years old up to September 2018, without language restrictions. Meta-analysis was based on a random effects model. The systematic review was registered as CRD42018094498. We identified 3,402 articles, of which eight studies with 10 effect sizes met the inclusion criteria. Vitamin D daily dose equivalents ranged from 600 to 4,000 per day to 60,000 IU per week; duration was 6 weeks to 36 months. In general, vitamin D supplementation had no significant effect on TT (MD = 0.20, 95% CI: -0.20, 0.60, p = 0.336) and SHBG (MD = 1.56, 95% CI: -0.85, 3.97, p = 0.204). Subgroup analysis conducted with duration of prescription, type (daily or weekly), dosing frequency and baseline vitamin D and TT concentration showed that vitamin D did not significantly affect TT. The present study did not find any evidence to support beneficial effect of vitamin D supplementation on TT and SHBG in men. Thus, further large-scale randomised controlled trials are required to evaluate the effects of vitamin D supplementation on androgen in men.

Role of diet in type 2 diabetes incidence: umbrella review of meta-analyses of prospective observational studies

OBJECTIVE

To summarise the evidence of associations between dietary factors and incidence of type 2 diabetes and to evaluate the strength and validity of these associations.

DESIGN

Umbrella review of systematic reviews with meta-analyses of prospective observational studies.

DATA SOURCES

PubMed, Web of Science, and Embase, searched up to August 2018.

ELIGIBILITY CRITERIA

Systematic reviews with meta-analyses reporting summary risk estimates for the associations between incidence of type 2 diabetes and dietary behaviours or diet quality indices, food groups, foods, beverages, alcoholic beverages, macronutrients, and micronutrients.

RESULTS

53 publications were included, with 153 adjusted summary hazard ratios on dietary behaviours or diet quality indices (n=12), food groups and foods (n=56), beverages (n=10), alcoholic beverages (n=12), macronutrients (n=32), and micronutrients (n=31), regarding incidence of type 2 diabetes. Methodological quality was high for 75% (n=115) of meta-analyses, moderate for 23% (n=35), and low for 2% (n=3). Quality of evidence was rated high for an inverse association for type 2 diabetes incidence with increased intake of whole grains (for an increment of 30 g/day, adjusted summary hazard ratio 0.87 (95% confidence interval 0.82 to 0.93)) and cereal fibre (for an increment of 10 g/day, 0.75 (0.65 to 0.86)), as well as for moderate intake of total alcohol (for an intake of 12-24 g/day v no consumption, 0.75 (0.67 to 0.83)). Quality of evidence was also high for the association for increased incidence of type 2 diabetes with higher intake of red meat (for an increment of 100 g/day, 1.17 (1.08 to 1.26)), processed meat (for an increment of 50 g/day, 1.37 (1.22 to 1.54)), bacon (per two slices/day, 2.07 (1.40 to 3.05)), and sugar sweetened beverages (for an increase of one serving/day, 1.26 (1.11 to 1.43)).

CONCLUSIONS

Overall, the association between dietary factors and type 2 diabetes has been extensively studied, but few of the associations were graded as high quality of evidence. Further factors are likely to be important in type 2 diabetes prevention; thus, more well conducted research, with more detailed assessment of diet, is needed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018088106.

Adherence to Dietary Approaches to Stop Hypertension (DASH)-Style Diet and the Risk of Cancer: A Systematic Review and Meta-Analysis of Cohort Studies

Objective: Several investigators have proposed a protective association between dietary approaches to stop hypertension (DASH) style diet and risk of cancers; however, they have had inconsistent results. The present study aimed to systematically review the prospective cohort studies and if possible quantify the overall effect using meta-analysis. Methods: PubMed, Scopus, and Google Scholar were searched for cohort studies published up to July 2018. Relative risks (RRs) that were reported for fully adjusted models and their confidence intervals were extracted for meta-analysis. The random effects model was used to combine the RRs. Results: Seventeen studies were eligible to be included in the systematic review, from which nine reports assessed the association between the DASH diet and risk of mortality from all cancer types, four assessed incidence of colorectal cancer, and two studies assessed the risk of colon and rectal cancer separately. Four studies examined the association with the incidence of other cancers (breast, hepatic, endometrial, and lung cancer). Meta-analysis showed that high adherence to DASH is associated with a decreased mortality from all cancer types (RR = 0.84, 95% confidence interval [95%CI]: 0.81-0.86). Participants with the highest adherence to the DASH diet had a lower risk of developing colorectal (RR = 0.79, 95%CI: 0.75-0.83), colon (RR = 0.80, 95%CI: 0.74-0.87), and rectal (RR = 0.84, 95%CI: 0.74-0.96) cancers compared to those with the lowest adherence. Conclusion: DASH-style diet should be suggested as a healthy approach associated with decreased risk of cancer in the community. Prospective studies exploring the association for other cancer types and from regions other than the United States are highly recommended.

The Philosophy of Evidence-Based Principles and Practice in Nutrition

The practice of evidence-based nutrition involves using the best available nutrition evidence, together with clinical experience, to conscientiously work with patients’ values and preferences to help them prevent (sometimes), resolve (sometimes), or cope with (often) problems related to their physical, mental, and social health. This article outlines the 3 fundamental principles of evidence-based practice as applied to the field of clinical nutrition. First, optimal clinical decision making requires awareness of the best available evidence, which ideally will come from unbiased systematic summaries of that evidence. Second, evidence-based nutrition provides guidance on how to decide which evidence is more or less trustworthy—that is, how certain can we be of our patients’ prognosis, diagnosis, or of our therapeutic options? Third, evidence alone is never sufficient to make a clinical decision. Decision makers must always trade off the benefits with the risks, burden, and costs associated with alternative management strategies, and, in so doing, consider their patients’ unique predicament, including their values and preferences.

Alpha-lipoic acid (ALA) supplementation effect on glycemic and inflammatory biomarkers: A Systematic Review and meta- analysis

BACKGROUND & AIMS

Several randomized clinical trials (RCTs) have investigated the effect of Alpha - Lipoic Acid (ALA) supplementation on metabolic parameters, with conflicting results. Therefore, the present study assessed the effect of ALA on some glycemic and inflammatory parameters.

METHODS

A comprehensive literature search was conducted up from inception to July 2018 on PubMed, Scopus, Cochrane databases, Google Scholar, ProQuest, Web of Science, and Embase. From among eligible trials, 41 articles were selected for the meta-analysis. Two reviewers independently assessed the risk of bias and extracted data from the included studies. Meta-analyses using the random-effects model were performed to analyze the data.

RESULTS

Based on the Cochrane risk of bias tool, 19 articles had a good quality, 16 trials had a poor quality and 6 trials had a fair quality. The results demonstrated the significant effect of ALA on Fasting Blood Sugar (FBS) (weighted mean difference (WMD)) = -6.57, 95% confidence interval (CI: -11.91 to -1.23, P = 0.016), Hemoglobin A1c (HbA1c) (WMD = -0.35, 95% CI: -0.55 to -0.15, P = 0.004), Tumor Necrosis Factor Alpha (TNF-α) (WMD = -1.57, 95% CI: -2.29 to -0.85, P < 0.05), Interleukin 6 levels (IL-6) (WMD = -1.15, 95% CI: -1.58 to -0.72, P < 0.001), and C-reactive protein (CRP) (WMD = -0.31, 95% CI: -0.47 to -0.16, P > 0.001). No effect was detected for ALA on insulin and the homeostatic model assessment of insulin resistance (HOMA-IR).

CONCLUSIONS

These findings suggest that ALA is a viable supplement to improve some of the glycemic and inflammatory biomarkers.

Food Groups and Risk of Overweight, Obesity, and Weight Gain: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies

This meta-analysis summarizes the evidence of a prospective association between the intake of foods [whole grains, refined grains, vegetables, fruit, nuts, legumes, eggs, dairy, fish, red meat, processed meat, and sugar-sweetened beverages (SSBs)] and risk of general overweight/obesity, abdominal obesity, and weight gain. PubMed and Web of Science were searched for prospective observational studies until August 2018. Summary RRs and 95% CIs were estimated from 43 reports for the highest compared with the lowest intake categories, as well as for linear and nonlinear relations focusing on each outcome separately: overweight/obesity, abdominal obesity, and weight gain. The quality of evidence was evaluated with use of the NutriGrade tool. In the dose-response meta-analysis, inverse associations were found for whole-grain (RRoverweight/obesity: 0.93; 95% CI: 0.89, 0.96), fruit (RRoverweight/obesity: 0.93; 95% CI: 0.86, 1.00; RRweight gain: 0.91; 95% CI: 0.86, 0.97), nut (RRabdominal obesity: 0.42; 95% CI: 0.31, 0.57), legume (RRoverweight/obesity: 0.88; 95% CI: 0.84, 0.93), and fish (RRabdominal obesity: 0.83; 95% CI: 0.71, 0.97) consumption and positive associations were found for refined grains (RRoverweight/obesity: 1.05; 95% CI: 1.00, 1.10), red meat (RRabdominal obesity: 1.10; 95% CI: 1.04, 1.16; RRweight gain: 1.14; 95% CI: 1.03, 1.26), and SSBs (RRoverweight/obesity: 1.05; 95% CI: 1.00, 1.11; RRabdominal obesity: 1.12; 95% CI: 1.04, 1.20). The dose-response meta-analytical findings provided very low to low quality of evidence that certain food groups have an impact on different measurements of adiposity risk. To improve the quality of evidence, better-designed observational studies, inclusion of intervention trials, and use of novel statistical methods (e.g., substitution analyses or network meta-analyses) are needed.

Chocolate and risk of chronic disease: a systematic review and dose-response meta-analysis

Purpose

Evidence for the association between chocolate intake and risk of chronic diseases is inconclusive. Therefore, we aimed to synthesize and evaluate the credibility of evidence on the dose-response association between chocolate consumption with risk of all-cause mortality, coronary heart disease (CHD), stroke, heart failure (HF), type 2 diabetes (T2D), colorectal cancer (CRC), and hypertension.

Methods

Prospective studies were searched until July 2018 in PubMed, Embase, and Web of Science. Random-effects meta-analyses comparing highest versus lowest intake categories, linear, and non-linear dose-response analyses were conducted. The credibility of evidence was evaluated with the NutriGrade scoring-system.

Results

Overall, 27 investigations were identified (n = 2 for all-cause mortality, n = 9 for CHD, n = 8 for stroke, n = 6 for HF, n = 6 for T2D, n = 2 for hypertension and CRC, respectively). No associations with HF (RR 0.99, 95% CI 0.94, 1.04) and T2D (RR 0.94, 95% CI 0.88, 1.01) per each 10 g/day increase in chocolate intake were observed in the linear dose-response meta-analyses. However, a small inverse association for each 10 g/daily increase could be shown for the risk of CHD (RR 0.96, 95% CI 0.93, 0.99), and stroke (RR 0.90, 95% CI 0.82, 0.98). The credibility of evidence was rated either very low (all-cause mortality, HF, T2D, CRC or hypertension) or low (CHD, stroke).

Conclusion

Chocolate consumption is not related to risk for several chronic diseases, but could have a small inverse association with CHD and stroke. Our findings are limited by very low or low credibility of evidence, highlighting important uncertainty for chocolate–disease associations.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-01914-9) contains supplementary material, which is available to authorized users.

Reducing waste in nutritional epidemiology: review and perspectives

We discuss efforts in improving the value of nutrition research. We organised the paper in five research stages: Stage 1: research priority setting; Stage 2: research design, conduct and analysis; Stage 3: research regulation and management; Stage 4: research accessibility and Stage 5: research reporting and publishing. Along the stages of the research cycle, varied initiatives exist to improve the quality and added value of nutrition research. However, efforts are focused on single stages of the research cycle without vision of the research system as a whole. Although research on nutrition research has been limited, it has potential to improve the quality of nutrition research and develop new tools and instruments for this purpose. A comprehensive assessment of the magnitude of research waste in nutrition and consensus on priority actions is needed. The nutrition research community at large needs to have open discussions on the usefulness of these tools and lead suitable efforts to enhance nutrition research across the stages of the research cycle. Capacity building is essential and considerations of nutrition research quality are vital to be integrated in training efforts of nutrition researchers.

Dietary and circulating vitamin C, vitamin E, β-carotene and risk of total cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective observational studies

OBJECTIVE

The present review aimed to quantify the association of dietary intake and circulating concentration of major dietary antioxidants with risk of total CVD mortality.

DESIGN

Systematic review and meta-analysis.

SETTING

Systematic search in PubMed and Scopus, up to October 2017.ParticipantsProspective observational studies reporting risk estimates of CVD mortality across three or more categories of dietary intakes and/or circulating concentrations of vitamin C, vitamin E and β-carotene were included. A random-effects meta-analysis was conducted.

RESULTS

A total of fifteen prospective cohort studies and three prospective evaluations within interventional studies (320 548 participants and 16 974 cases) were analysed. The relative risks of CVD mortality for the highest v. the lowest category of antioxidant intakes were as follows: vitamin C, 0·79 (95 % CI 0·68, 0·89; I 2=46 %, n 10); vitamin E, 0·91 (95 % CI 0·79, 1·03; I 2=51 %, n 8); β-carotene, 0·89 (95 % CI 0·73, 1·05; I 2=34 %, n 4). The relative risks for circulating concentrations were: vitamin C, 0·60 (95 % CI 0·42, 0·78; I 2=65 %, n 6); α-tocopherol, 0·82 (95 % CI 0·76, 0·88; I 2=0 %, n 5); β-carotene, 0·68 (95 % CI 0·52, 0·83; I 2=50 %, n 6). Dose-response meta-analyses demonstrated that the circulating biomarkers of antioxidants were more strongly associated with risk of CVD mortality than dietary intakes.

CONCLUSIONS

The present meta-analysis demonstrates that higher vitamin C intake and higher circulating concentrations of vitamin C, vitamin E and β-carotene are associated with a lower risk of CVD mortality.

Hesperidin, a major flavonoid in orange juice, might not affect lipid profile and blood pressure: A systematic review and meta-analysis of randomized controlled clinical trials

Previous studies have led to conflicting results regarding the effect of hesperidin supplementation on cardiometabolic markers. This study aimed to evaluate the efficacy of hesperidin supplementation on lipid profile and blood pressure through a systematic review and meta-analysis of randomized controlled trials (RCTs). PubMed, Web of Science, Scopus, and Google Scholar, as well as the reference lists of the identified relevant RCTs, were searched up to May 2018. Effect sizes were pooled by using the random effects model. Ten RCTs (577 participants) were eligible to be included in the systematic review. The meta-analysis revealed that hesperidin supplementation had no effect on serum total cholesterol (weighted mean difference [WMD] = -1.04 mg/dl; 95% confidence interval [CI]: -5.65, 3.57), low-density lipoprotein cholesterol (WMD = -1.96 mg/dl; 95% CI [-7.56, 3.64]), high-density lipoprotein cholesterol (WMD = 0.16 mg/dl; 95% CI [-1.94, 2.28]), and triglyceride (WMD = 0.69 mg/dl; 95% CI [-5.91, 7.30]), with no significant between-study heterogeneity. Hesperidin supplement also had no effect on systolic (WMD = -0.85 mmHg; 95% CI [-3.07, 1.36]) and diastolic blood pressure (WMD = -0.48 mmHg; 95% CI [-2.39, 1.42]). Hesperidin supplementation might not improve lipid profile and blood pressure. Future well-designed trials are still needed to confirm these results.

Perspective: The Evidence-Based Framework in Nutrition and Dietetics: Implementation, Challenges, and Future Directions

Decision making in nutrition is based on current available scientific evidence. However, we are currently living in a time of highly accessible information, and with the increase in accessibility has come a concomitant increase in misinformation and pseudoscience relating to nutrition. This presents a challenge to the nutrition research community, practitioners, and consumers, and highlights a need to critically examine the current evidence-based framework in nutrition, and identify strategies for future improvements. This narrative review outlines the current evidence-based framework and approaches to evidence-based practice in the nutrition field, focusing on policy and guideline development. Within the framework, systematic reviews are an important tool for evidence-based practice, underpinning translation guidelines and other implementation documents. Recommendations for consumption of nutrients, foods, and whole diets are required to guide consumers and practitioners; however, these resources must be updated regularly to remain timely and accurate. In turn, clinical practice guidelines guide practitioners in how to implement the evidence base for patients and clients, supporting practitioners to be positioned as a key conduit between scientific evidence and the public. In contrast, health claims may support marketing of food products, but require consideration of the strength and quality of the evidence to support health claims, with external oversight required to ensure claims are appropriate. Collecting, synthesizing, and translating the evidence base in nutrition remains an ongoing challenge, particularly in the current context of increased information availability. To address growing challenges in combating pseudoscience, nutrition researchers, policy makers, and practitioners must work together, and the role of practitioners in translating the evidence base and personalizing it to individual patients must be emphasized. Continuing to address current challenges, including increasing the timeliness and consistency of the approach to the evidence base, is required to ensure informed and robust nutrition policy, research, and practice into the future.

Intake of vitamin B6, folate, and vitamin B12 and risk of coronary heart disease: a systematic review and dose-response meta-analysis of prospective cohort studies

The objective of this study was to quantify the association of B-vitamins intake with the future risk of coronary heart disease (CHD). A systematic search was performed with the use of PubMed and Scopus from inception to April 30, 2018. Prospective cohort studies evaluating the association of intake of folate, vitamin B6, and vitamin B12 with risk of CHD in the general population were included. A random-effects meta-analysis was performed. Eleven prospective cohort studies (total n = 369,746) with 5133 cases of CHD were included in the analyses. The relative risks were: 0.79 (95%CI: 0.69, 0.89; I² = 67%) for a 250 µg/d increment in folate intake; 0.87 (95%CI: 0.78, 0.96; I² = 80%) for a 0.5 mg/d increment in vitamin B6 intake; and 0.97 (95%CI: 0.80, 1.14: I² = 67%) for a 3 µg/d increment in vitamin B12 intake. The results did not change materially when the analyses were restricted only to dietary vitamins intake. A nonlinear dose-response meta-analysis demonstrated a linear inverse association between folate and vitamin B6 intake and risk of CHD. In conclusion, higher intake of folate and vitamin B6 is associated with a lower risk of CHD in the general population.

Development and reliability assessment of a new quality appraisal tool for cross-sectional studies using biomarker data (BIOCROSS)

Background

Biomarker-based analyses are commonly reported in observational epidemiological studies; however currently there are no specific study quality assessment tools to assist evaluation of conducted research. Accounting for study design and biomarker measurement would be important for deriving valid conclusions when conducting systematic data evaluation.

Methods

We developed a study quality assessment tool designed specifically to assess biomarker-based cross-sectional studies (BIOCROSS) and evaluated its inter-rater reliability. The tool includes 10-items covering 5 domains: ‘Study rational’, ‘Design/Methods’, ‘Data analysis’, ‘Data interpretation’ and ‘Biomarker measurement’, aiming to assess different quality features of biomarker cross-sectional studies. To evaluate the inter-rater reliability, 30 studies were distributed among 5 raters and intraclass correlation coefficients (ICC-s) were derived from respective ratings.

Results

The estimated overall ICC between the 5 raters was 0.57 (95% Confidence Interval (CI): 0.38–0.74) indicating a good inter-rater reliability. The ICC-s ranged from 0.11 (95% CI: 0.01–0.27) for the domain ‘Study rational’ to 0.56 (95% CI: 0.40–0.72) for the domain ‘Data interpretation’.

Conclusion

BIOCROSS is a new study quality assessment tool suitable for evaluation of reporting quality from cross-sectional epidemiological studies employing biomarker data. The tool proved to be reliable for use by biomedical scientists with diverse backgrounds and could facilitate comprehensive review of biomarker studies in human research.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0583-x) contains supplementary material, which is available to authorized users.

Systematic Analysis of Evidence and Sound Expert Assessment: Two Enablers of Evidence-Based Decision-Making in Health

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