The effects of resveratrol intake on weight loss: a systematic review and meta-analysis of randomized controlled trials

Abstract

This systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize the effect of resveratrol intake on weight loss. We searched the following databases until July 2018: MEDLINE, EMBASE, Web of Science and Cochrane Central Register of Controlled Trials. Data were pooled using the inverse variance method and expressed as standardized mean difference (SMD) with 95% confidence intervals (95% CI). Out of 831 reports, 36 RCTs were eligible for including to our meta-analysis. The pooled results, using random-effects model showed that resveratrol supplementation significantly decreased body weight (SMD?=??0.17; 95% CI, ?0.33, ?0.01; P?=?0.03; I²: 62.6), body mass index (BMI) (SMD?=??0.20; 95% CI, ?0.35, ?0.05; P?=?0.01; I²: 60.6), fat mass (SMD?=??0.32; 95% CI, ?0.62, ?0.03; P?=?0.03; I²: 77.9) and waist circumference (WC) (SMD?=??0.42; 95% CI, ?0.68, ?0.16; P?=?0.001; I²: 75.2), and significantly increased lean mass (SMD?=?1.21; 95% CI, 0.75, 1.67; P?<?0.001; I²: 87.6). We found no significant effect of resveratrol administration on leptin (SMD?=??0.20; 95% CI, ?0.68, 0.27; P?=?0.40; I²: 85.3) and adiponectin levels (SMD?=?0.08; 95% CI, ?0.39, 0.55; P?=?0.74; I²: 91.0). Resveratrol supplementation significantly decreased body weight in obese patients (SMD ?0.43; 95% CI, ?0.60, ?0.26) compared with other diseases (SMD 0.02; 95% CI, ?0.29, 0.33), and type 2 diabetes mellitus (SMD ?0.17; 95% CI, ?0.37, 0.02). Overall, the current meta-analysis demonstrated that resveratrol intake significantly reduced weight, BMI, WC and fat mass, and significantly increased lean mass, but did not affect leptin and adiponectin levels.     

The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials

Abstract

This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effect of caffeine intake on weight loss. We searched the following databases until November 2017: MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials. The relevant data were extracted and assessed for quality of the studies according to the Cochrane risk of bias tool. We estimated an intake-status regression coefficient (Beta) for each primary study and estimated the overall pooled Beta and SE using random effects meta-analysis on a double-log scale. Heterogeneity between studies was assessed by the Cochran Q statistic and I-squared tests (I²). Thirteen RCTs with 606 participants were included in the meta-analyses. The overall pooled Beta for the effect of caffeine intake was 0.29 (95%CI: 0.19, 0.40; Q = 124.5, I²?=?91.2%) for weigh, 0.23 (95%CI: 0.09, 0.36; Q = 71.0, I²?=?93.0%) for BMI, and 0.36 (95% CI: 0.24, 0.48; Q = 167.36, I²?=?94.0%) for fat mass. For every doubling in caffeine intake, the mean reduction in weight, BMI, and fat mass increased 2 Beta-fold (20.29 = 1.22, 20.23 = 1.17, and 20.36 = 1.28), which corresponding to 22, 17, and 28 percent, respectively. Overall, the current meta-analysis demonstrated that caffeine intake might promote weight, BMI and body fat reduction.     

The effects of quercetin supplementation on lipid profiles and inflammatory markers among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized controlled trials

Abstract

Aims: This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to determine the effect of quercetin administration on lipid profiles and inflammatory markers among patients with metabolic syndrome (MetS) and related disorders.

Methods: We searched systematically online databases including Cochrane Library, EMBASE, MEDLINE, and Web of Science to identify the relevant RCTs until November 2018. Q-test and I² statistics were applied to assess heterogeneity among included studies. Data were combined using fixed- or random-effects model and presented as standardized mean difference (SMD) with 95% confidence interval (CI).

Results: Out of 591 citations, 16 RCTs were included in the meta-analysis. The pooled findings showed that quercetin consumption significantly decreased total-cholesterol (SMD = ?0.98; 95% CI, ?1.48, ?0.49; p?<?0.001; I²: 94.0), LDL-cholesterol (SMD = ?0.88; 95% CI, ?1.35, ?0.41; p?<?0.001; I²: 92.7) and C-reactive protein (CRP) levels (?0.64; 95% CI, ?1.03, ?0.25; p?=?0.001; I²: 90.2). While, quercetin supplementation did not significantly affect triglycerides (TG) (SMD = ?0.32; 95% CI, ?0.68, 0.04; p?=?0.08; I²: 84.8), HDL-cholesterol (SMD = 0.20; 95% CI, ?0.20, 0.24; p?=?0.84; I²: 70.6), interleukin 6 (IL-6) (SMD = ?0.69; 95% CI, ?1.69, 0.31; p?=?0.17; I²: 94.5) and tumor necrosis factor-alpha (TNF-α) levels (SMD = ?0.06; 95% CI, ?0.25, 0.14; p?=?0.58; I²: 35.6)

Conclusions: In summary, the current meta-analysis demonstrated that quercetin supplementation significantly reduced total-cholesterol, LDL-cholesterol, and CRP levels, yet did not affect triglycerides, HDL-cholesterol, IL-6 and TNF-α among patients with MetS and related disorders.     

The effects of psyllium supplementation on body weight,body mass index and waist circumference in adults: A systematic review and dose-response meta-analysis of randomized controlled trials

Abstract

Background: Previous studies reported inconsistent findings regarding the effects of psyllium supplementation on obesity measures. This systematic review and meta-analysis was performed to summarize data from available randomized clinical trials (RCTs) on the effect of psyllium supplementation on body weight, body mass index (BMI), and waist circumference (WC) in adults.

Methods: PubMed, SCOPUS, Cochrane Library, and Google Scholar were searched to identify relevant articles up to August 2018. The effect sizes were presented as weighted mean difference (WMD) and 95% confidence intervals (CI) by using random effects model. To detect dose-response relationships, we used fractional polynomial modeling.

Results: A total of 22 RCTs were included. Meta-analysis did not find any significant effect of psyllium supplementation on body weight (MD: ?0.28?kg, 95% CI: ?0.78, 0.21, p?=?0.268), BMI (MD: ?0.19?kg/m², 95% CI: ?0.55, 0.15, p?=?0.27) and WC (MD: ?1.2?cm, 95% CI: ?2.6, 0.2, p?=?0.09). Subgroup analysis showed that psyllium dosage, kind of psyllium administration, duration of trial, study design, sample size, and gender were potential sources of heterogeneity. Moreover, there was nonlinear association between duration of psyllium consumption, BMI and WC.

Conclusion: Psyllium supplementation does not reduce body weight, BMI, and WC significantly.     

Prevalence of overweight and obesity among indigenous populations in Canada: A systematic review and meta-analysis

Previous studies on overweight and obesity among indigenous peoples in Canada have been inconclusive. A systematic review was conducted on the prevalence of overweight and obesity among Canadian indigenous populations. Major bibliographic databases were searched for relevant studies published between January 1990 and June 2013. We reviewed 594 abstracts and included 41 studies in the meta-analyses. Using the heterogeneity test (Cochrane Q) results, the overall prevalence was estimated using fixed- or random-effects model. Nonadults (<18 years) had a pooled prevalence of overweight and obesity at 29.8% (95% CI: 25.2–34.4) and 26.5% (95% CI: 21.8–31.3), respectively. The pooled prevalence of overweight and obesity among adults were 29.7% (95% CI: 28.2–31.2) and 36.6% (95% CI: 32.9–40.2), respectively. Adult males had higher overweight prevalence than females (34.6% vs. 26.6%), but lower obesity prevalence (31.6% vs. 40.6%). Nonadult girls had higher prevalence than boys [overweight: 27.6%; 95% CI: 22.6–32.7 vs. 24.7%; 95% CI: 19.0–30.5; obesity: 28.6%; 95% CI: 20.3–36.9 vs. 25.1%; 95% CI: 13.8–36.4]. Nonadult Inuit had the highest overweight and lowest obesity prevalence. Although Inuit adult had the lowest prevalence of overweight (28.7%; 95% CI: 27.3–30.2) and obesity (32.3%; 95% CI: 25.5–39.1), it was relatively high. This study highlights the need for nutritional intervention programs for obesity prevention among indigenous populations in Canada.     

Effect of resveratrol on blood pressure: A systematic review and meta-analysis of randomized,controlled, clinical trials

Introduction: Results of previous clinical trials evaluating the effect of resveratrol supplementation on blood pressure (BP) are controversial.

Purpose: We aimed to assess the impact of resveratrol on BP through systematic review of literature and meta-analysis of available randomized, controlled clinical trials (RCTs).

Methods: Literature search included SCOPUS, PubMed-Medline, ISI Web of Science and Google Scholar databases up to 17th October 2017 to identify RCTs investigating the impact of resveratrol on BP. Two review authors independently extracted data on study characteristics, methods and outcomes. Overall, the impact of resveratrol on BP was reported in 17 trials.

Results: Administration of resveratrol did not significantly affect neither systolic BP [weighted mean difference (WMD): ?2.5 95% CI:(-5.5, 0.6) mmHg; p=0.116; I²=62.1%], nor diastolic BP [WMD: ?0.5 95% CI:(-2.2, 1.3) mmHg; p=0.613; I²=50.8], nor mean BP [MAP; WMD: ?1.3 95% CI:(-2.8, 0.1) mmHg; p=0.070; I²=39.5%] nor pulse pressure [PP; WMD: ?0.9 95% CI:(-3.1, 1.4) mmHg; p=0.449; I²=19.2%]. However, significant WMDs were detected in subsets of studies categorized according to high resveratrol daily dosage (≥300 mg/day) and presence of diabetes. Meta-regression analysis revealed a positive association between systolic BP-lowering resveratrol activity (slope: 1.99; 95% CI: 0.05, 3.93; two-tailed p= 0.04) and Body Mass Index (BMI) at baseline, while no association was detected neither between baseline BMI and MAP-lowering resveratrol activity (slope: 1.35; 95% CI: ?0.22, 2.91; two-tailed p= 0.09) nor between baseline BMI and PP-lowering resveratrol activity (slope: 1.03; 95% CI: ?1.33, 3.39; two-tailed p= 0.39). Resveratrol was fairly well-tolerated and no serious adverse events occurred among most of the eligible trials.

Conclusion: The favourable effect of resveratrol emerging from the current meta-analysis suggests the possible use of this nutraceutical as active compound in order to promote cardiovascular health, mostly when used in high daily dose (≥300 mg/day) and in diabetic patients.     

Effect of wheat germ on metabolic markers: a systematic review and meta-analysis of randomized controlled trials

Food Science and Biotechnology - This systematic review and meta-analysis aim to evaluate the association of wheat germ interventions and metabolic markers. An electronic search was performed by...     

Lipid-modifying activity of curcuminoids: A systematic review and meta-analysis of randomized controlled trials

Objective: The aim of this systematic review and meta-analysis was to determine and clarify the impact of curcuminoids on serum lipid levels. Methods: Randomized controlled trials (RCTs) investigating the effects of curcuminoids on plasma lipids were searched in PubMed-Medline, Scopus, Web of Science databases (from inception to April 3^rd, 2017). A random-effects model and generic inverse variance method were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. A weighted random-effects meta-regression was performed to evaluate the impact of potential confounders on lipid concentrations. Results: A meta-analysis of 20 RCTs with 1427 participants suggested a significant decrease in plasma concentrations of triglycerides (WMD: ?21.36 mg/dL, 95% CI: ?32.18, ?10.53, p < 0.001), and an elevation in plasma HDL-C levels (WMD: 1.42 mg/dL, 95% CI: 0.03, 2.81, p = 0.046), while plasma levels of LDL-C (WMD: ?5.82 mg/dL, 95% CI: ?15.80, 4.16, p = 0.253) and total cholesterol (WMD: ?9.57 mg/dL, 95% CI: ?20.89, 1.75, p = 0.098) were not altered. The effects of curcuminoids on lipids were not found to be dependent on the duration of supplementation. Conclusion: This meta-analysis has shown that curcuminoid therapy significantly reduces plasma triglycerides and increases HDL-C levels.     

The effects of supplementation with conjugated linoleic acid on anthropometric indices and body composition in overweight and obese subjects: A systematic review and meta-analysis

Abstract

Clinical trials have indicated conflicting results on the effects of conjugated linoleic acid (CLA) on obesity. The present study aimed to systematically review controlled clinical trials examining the effects of CLA on anthropometric indices and body composition in overweight and obese subjects. Pubmed, Scopus, Web of science, and Cochrane databases were searched between 2000 and December 2017 with no language restriction. Placebo-controlled clinical trials that reported anthropometric indices and body composition in overweight and obese subjects were included. Random-effect model was used to pool the effect estimates. Of 4032 publications, 13 trials were included for the meta-analysis. Pooled effect sizes indicated that CLA significantly reduced body weight (WMD: ?0.52 kg, 95% CI: ?0.83, ?0.21; I²: 48.0%, p?=?0.01), BMI (WMD: ?0.23 kg/m², 95% CI: ?0.39,???0.06; I²: 64.7%, p?=?0.0001), FM (WMD: ?0.61 kg, 95% CI: ?0.98, ?0.24; I²: 53.8%, p?=?0.01) and increased LBM (WMD: 0.19 kg, 95% CI: 0.04, 0.34; I²: 81.4%, p?=?0.0001) compared to the placebo group. However, the effects of CLA on WC (WMD: 0.05 cm, 95% CI: ?0.01, 0.1; I²: 0%, p?=?0.93) was not significant. Additionally, its impact on body weight in subjects older than 44 year (WMD: ?1.05 kg, 95% CI: ?1.75, ?0.35; I²: 57.0%, p?=?0.01), with longer duration (more than 12 weeks) (WMD: ?1.29 kg, 95% CI: ?2.29, ?0.29; I²: 70.3%, p?=?0.003) and dosage more than 3.4 g/day (WMD: ?0.77 kg, 95% CI: ?1.28, ?0.25; I²: 62.7%, p?=?0.004) were greater than comparative groups. Supplementation with CLA can slightly reduce body weight and FM and increase LBM in overweight and obese subjects. However, its efficacy was not clinically considerable. Further studies with high methodological quality are needed to shed light on the effects of CLA on anthropometric indices in overweight and obese subjects.     

Metabolic effects of aspartame in adulthood: A systematic review and meta-analysis of randomized clinical trials

Data about harms or benefits associated with the consumption of aspartame, a nonnutritive sweetener worldwide consumed, are still controversial. This systematic review and meta-analysis of randomized controlled clinical trials aimed to assess the effect of aspartame consumption on metabolic parameters related to diabetes and obesity. The search was performed on Cochrane, LILACS, PubMed, SCOPUS, Web of Science databases, and on a gray literature using Open Grey, Google Scholar, and ProQuest Dissertations &; Theses Global. Searches across all databases were conducted from the earliest available date up to April 13, 2016, without date and language restrictions. Pooled mean differences were calculated using a random or fixed-effects model for heterogeneous and homogenous studies, respectively. Twenty-nine articles were included in qualitative synthesis and twelve, presenting numeric results, were used in meta-analysis. Fasting blood glucose (mmol/L), insulin levels (μU/mL), total cholesterol (mmol/L), triglycerides concentrations (mmol/L), high-density lipoprotein cholesterol (mmol/L), body weight (kg), and energy intake (MJ) were considered as the main outcomes in subjects that consumed aspartame, and results were presented as mean difference; % confidence interval, range. Aspartame consumption was not associated with alterations on blood glucose levels compared to control (?0.03 mmol/L; 95% CI, ?0.21 to 0.14) or to sucrose (0.31 mmol/L; 95% CI, ?0.05 to 0.67) and on insulin levels compared to control (0.13 μU/mL; 95% CI, ?0.69 to 0.95) or to sucrose (2.54 μU/mL; 95% CI, ?6.29 to 11.37). Total cholesterol was not affected by aspartame consumption compared to control (?0.02 mmol/L; 95% CI, ?0.31 to 0.27) or to sucrose (?0.24 mmol/L; 95% CI, ?0.89 to 0.42). Triglycerides concentrations were not affected by aspartame consumption compared to control (0.00 mmol/L; 95% CI, ?0.04 to 0.05) or to sucrose (0.00 mmol/L; 95% CI, ?0.09 to 0.09). High-density lipoprotein cholesterol serum levels were higher on aspartame compared to control (?0.03 mmol/L; 95% CI, ?0.06 to ?0.01) and lower on aspartame compared to sucrose (0.05 mmol/L; 95% CI, 0.02 to 0.09). Body weight did not change after aspartame consumption compared to control (5.00 kg; 95% CI, ?1.56 to 11.56) or to sucrose (3.78 kg; 95% CI, ?2.18 to 9.74). Energy intake was not altered by aspartame consumption compared to control (?0.49 MJ; 95% CI, ?1.21 to 0.22) or to sucrose (?0.17 MJ; 95% CI, ?2.03 to 1.69). Data concerning effects of aspartame on main metabolic variables associated to diabetes and obesity do not support a beneficial related to its consumption.     

Sodium status and the metabolic syndrome: A systematic review and meta-analysis of observational studies

The prevalence of metabolic syndrome (MetS) has been greatly increased, worldwide. In recent years, investigators have proposed that sodium might contribute to the development of metabolic syndrome; however, the published data were conflicting. The present systematic review aimed to summarize the evidence from observational studies in this regard. We conducted a systematic search for relevant observational studies investigating the association between sodium status and MetS, published until June 2017 in electronic databases including PubMed, EMBASE, Scopus and Google Scholar. Summary effects were derived using random effects model. After screening the records, seventeen publications with 66,274 participants were eligible to be included in the systematic review and meta-analysis. The analysis revealed that subjects with MetS have significantly higher levels of sodium compared to healthy controls (Hedges' g = 0.21, 95% CI: 0.12, 0.29, I² = 68.6). Subgroup analyses revealed that the difference was significant when the sodium status was assessed using urinary sodium levels. The random effects meta-regression analysis also revealed that body sodium level increases with the number of MetS components. Furthermore, participants with highest dietary/urinary or serum sodium levels had 37% higher chance of developing MetS when compared with participants with the lowest sodium levels (OR = 1.37 95%CI: 1.31, 1.42, I² = 86.9). The current meta-analysis revealed that higher sodium input into the body is directly associated with the likelihood of MetS. Prospective cohort studies and well-designed randomized clinical trials considering the effect of sodium restricted diets on the risk of MetS as an outcome are necessary to represent the causal association.     

Mediterranean diet,cardiovascular disease and mortality in diabetes: A systematic review and meta-analysis of prospective cohort studies and randomized clinical trials

Abstract

To update the clinical practice guidelines for nutrition therapy of the European Association for the Study of Diabetes, we conducted a systematic review and meta-analysis of prospective cohort studies and randomized clinical trials (RCTs) to evaluate the effect of the Mediterranean diet (MedDiet) on the prevention of cardiovascular disease (CVD) incidence and mortality. We searched Medline, EMBASE (through April 20, 2018) and Cochrane (through May 7, 2018) databases. Pooled relative risks (RRs) and 95% confidence interval (CI) were calculated by the generic inverse variance method. A total of 41 reports (3 RCTs and 38 cohorts) were included. Meta-analyses of RCTs revealed a beneficial effect of the MedDiet on total CVD incidence (RR: 0.62; 95% CI: 0.50, 0.78) and total myocardial infarction (MI) incidence (RR: 0.65; 95% CI: 0.49, 0.88). Meta-analyses of prospective cohort studies, which compared the highest versus lowest categories of MedDiet adherence, revealed an inverse association with total CVD mortality (RR: 0.79; 95% CI: 0.77, 0.82), coronary heart disease (CHD) incidence (RR: 0.73; 95% CI: 0.62, 0.86), CHD mortality (RR: 0.83; 95% CI: 0.75, 0.92), stroke incidence (RR: 0.80; 95% CI: 0.71, 0.90), stroke mortality (RR: 0.87; 95% CI: 0.80, 0.96) and MI incidence (RR: 0.73; 95% CI: 0.61, 0.88). The present study suggests that MedDiet has a beneficial role on CVD prevention in populations inclusive of individuals with diabetes.     

Modification of appetite by bread consumption: A systematic review of randomized controlled trials

The inclusion of different ingredients or the use of different baking technologies may modify the satiety response to bread, and aid in the control of food intake. The aim of this study was to perform a systematic search of randomized clinical trials on the effect of bread consumption on appetite ratings in humans. The search equation was (“Bread”[MeSH]) AND (“Satiation”[MeSH] OR “Satiety response”[MeSH]), and the filter “clinical trials.” As a result of this procedure, 37 publications were selected. The satiety response was considered as the primary outcome. The studies were classified as follows: breads differing in their flour composition, breads differing in ingredients other than flours, breads with added organic acids, or breads made using different baking technologies. In addition, we have revised the data related to the influence of bread on glycemic index, insulinemic index and postprandial gastrointestinal hormones responses. The inclusion of appropriate ingredients such as fiber, proteins, legumes, seaweeds and acids into breads and the use of specific technologies may result in the development of healthier breads that increase satiety and satiation, which may aid in the control of weight gain and benefit postprandial glycemia. However, more well-designed randomized control trials are required to reach final conclusions.     

Prevalence and characteristics of overweight and obesity in indigenous Australian children: A systematic review

Evidence-based profiling of obesity and overweight in Indigenous Australian children has been poor. This study systematically reviewed evidence of the prevalence and patterns of obesity/overweight, with respect to gender, age, remoteness, and birth weight, in Indigenous Australian children, 0–18 years (PROSPERO CRD42014007626). Study quality and risk of bias were assessed. Twenty-five publications (21 studies) met inclusion criteria, with large variations in prevalence for obesity or overweight (11 to 54%) reported. A high degree of heterogeneity in study design was observed, few studies (6/21) were representative of the target population, and few appropriately recruited Indigenous children (8/21). Variability in study design, conduct, and small sample sizes mean that it is not possible to derive a single estimate for prevalence although two high-quality studies indicate at least one in four Indigenous Australian children are overweight or obese. Four of six studies reporting on gender, found overweight/obesity higher in girls and eight studies reporting on overweight/obesity by age suggest prevalence increases with age with one high quality large national study reporting total overweight/obesity as 22.4% of children aged 2–4 years, 27.5% of those aged 5–9, 38.5% aged 10–14, and 36.3% aged 15–17. Three of four studies, reporting obesity/overweight by region, found lower rates for children living in more remote areas than urban areas.     

Dietary intake of fish,n-3 polyunsaturated fatty acids and risk of hip fracture: A systematic review and meta-analysis on observational studies

Previous studies have shown that fish consumption and dietary intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) are associated with hip fracture; however, findings were conflicting. The present review aimed to summarize the current evidence on the association of fish consumption and dietary intake of n-3 PUFAs with hip fracture. The online databases of PubMed, ISI Web of Science, Scopus, ProQuest, Science Direct and Embase were searched until August 2017 for related publications using relevant keywords. To pool data, either a fixed-effects model or random-effects models were used. Cochran's Q tests were used to assess heterogeneity between studies. In total, 10 studies (7 prospective and 3 case-control studies) were included in this systematic review, and 9 studies with total sample size of 292657 participants were included in the meta-analysis. The age of participants was 20 years or older. Combining 8 effect sizes from 4 prospective studies and 2 case-control studies revealed a significant inverse association between fish consumption and risk of hip fracture (pooled effect size: 0.88, 95% CI: 0.79-0.98, P = 0.02). Although this relationship became non-significant in prospective studies, a significant inverse association was found in prospective studies with sample size of 10000 individuals or more, and studies that considered body mass index as a covariate. Furthermore, dietary intake of n-3 PUFAs was inversely associated with risk of hip fracture (pooled effect size: 0.89, 95% CI: 0.80-0.99, P = 0.02). Also, such relationship was seen after excluding one case-control study and combining effect sizes only from prospective studies (pooled effect size: 0.88, 95% CI: 0.80-0.98, P = 0.02). In conclusion, we found that fish consumption and dietary intake of n-3 PUFAs might have protective effects on bone health and decline the risk of hip fracture.     

The effects of early life polyunsaturated fatty acids and ruminant trans fatty acids on allergic diseases: A systematic review and meta-analysis

Early life nutritional exposures could modify the gene expression and susceptibility of allergic diseases (AD). This systematic review aimed to evaluate whether early life (the first 1,000 days) natural exposure to polyunsaturated fatty acids (PUFA) and ruminant trans fatty acids (R-TFA) could affect the AD risk. We searched PubMed, EMBASE, PsycINFO, Scopus, the Cochrane Library, and ClinicalTrials.gov from inception through September 10, 2017 for relevant full-text articles in English. Observational studies were selected if they examined the effects of early life PUFA or R-TFA on AD (eczema, asthma, wheeze, and allergic rhinitis) or sensitization. The quality of studies was examined by the Newcastle-Ottawa Scale, and the best evidence synthesis (BES) was applied. We included 26 observational studies, and 8 of them showed high quality. BES showed a moderate evidence for the protective effect of vaccenic acid (VA, an R-TFA) on eczema, while insufficient or no evidence was found in other associations. Meta-analysis showed that higher n-6/n-3 ratio and linoleic acid were associated with higher risk of eczema (pooled odds ratio [OR] = 1.06, 95% confidence intervals [CI]: 1.00 ?1.13; 1.08, 95% CI: 1.01 ?1.15). However, VA was inversely associated with eczema pooled OR = 0.42, 95% CI: 0.25 ?0.72). Early life natural exposure to VA showed evident benefit on decreasing the risk of eczema, while PUFA and other R-TFA showed limited effects on AD. More robust studies especially for R-TFA are required.     

The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis

Background: Vegetarian diets exclude meat, seafood, and products containing these foods. Although the vegetarian lifestyle could lead to a better health status in adults, it may also bear risks for certain nutritional deficiencies. Cross-sectional studies and narrative reviews have shown that the iron status of vegetarians is compromised by the absence of highly bioavailable haem-iron in meatless diets and the inhibiting effect of certain components present in plant foods on non-haem iron bioavailability.

Methods: The databases Pubmed, Scopus, Embase, and Cochrane CentralRegister of Controlled Trials were searched for studies comparing serum ferritin, as the major laboratory parameter for iron status of adult vegetarians with non-vegetarian control groups. A qualitative review was conducted as well as an inverse-variance random-effects meta-analysis to pool available data. In addition the effect of vegetarian diets according to gender was investigated with a subgroup analysis. The results were validated using a sensitivity analysis.

Results: A total of 27 cross-sectional studies and three interventional studies were selected for the systematic review. The meta-analysis which combined data of 24 cross-sectional studies showed that adult vegetarians have significantly lower serum ferritin levels than their non-vegetarian controls (?29.71 µg/L, 95% CI [?39.69, ?19.73], p < 0.01). Inclusion of semi-vegetarian diets did not change the results considerably (?23.27 µg/L, 95% CI [?29.77, ?16.76], p < 0.01). The effects were more pronounced in men (?61.88 µg/L, 95% CI [?85.59, ?38.17], p < 0.01) than in both premenopausal women (?17.70 μg/L, 95% CI [?29.80, ?5.60], p < 0.01) and all women (?13.50 μg/L, 95% CI [?22.96, ?4.04], p < 0.01), respectively.

Conclusions: In conclusion our results showed that vegetarians are more likely to have lower iron stores compared with non-vegetarians. However, since high iron stores are also a risk factor for certain non-communicable diseases, such as type 2 diabetes, it is recommended that not only vegetarians but also non-vegetarians should regularly control their iron status and improve their diet regarding the content and bioavailability of iron by consuming more plants and less meat.     

Invited review: Effectiveness of precalving treatment on postcalving udder health in nulliparous dairy heifers: A systematic review and meta-analysis

Clinical mastitis affects 3% of primiparous dairy cattle (heifers) in the first month after calving. Additionally, the prevalence of intramammary infection (IMI) in the months before first calving is high, resulting in a high prevalence of heifers calving with IMI. Precalving therapy is an accepted recommendation for reducing mastitis in multiparous cows, but prophylactic treatment for heifers is uncommon in North America. Objectives of this study were to (1) quantify changes in postcalving udder health in heifers following application of a precalving treatment; (2) compare effectiveness among various types of treatments; and (3) compare effectiveness of various types of treatments against specific pathogens. A systematic review was conducted comparing interventions aimed at improving udder health in heifers. Of 62 included studies, 48 clinical trials were used in a meta-analysis. Data were synthesized using a random effects model for meta-analysis, followed by sub-group analyses comparing treatment types, and specific pathogens with statistical testing using meta-regression. Occurrence of mastitis (defined as elevated somatic cell count, clinical mastitis, and IMI) was reduced in treated heifers compared with untreated controls with a pooled risk ratio of treated to untreated heifers of 0.56 (95% confidence interval: 0.47 to 0.67). Upon stratification by treatment types, teat sealants and combination therapies (vaccines and antimicrobials; antimicrobials and teat sealants; and all 3) were most effective at improving udder health with pooled risk ratios of 0.40 (95% confidence interval: 0.30 to 0.52) and 0.34 (95% confidence interval: 0.25 to 0.45), respectively. Antimicrobials and vaccines also reduced occurrence of IMI and subclinical and clinical mastitis when compared with untreated heifers. Although variation was observed in the pathogen-specific effectiveness of treatments at reducing rates of disease, antimicrobials, teat sealants, and combinations of vaccines or teat sealants with antimicrobials were consistently effective, whereas vaccines were only effective for contagious pathogens. Recommendations for use of antibiotics should consider their relative benefit while also considering potential for increasing antimicrobial resistance.     

The effects of steamed ginger ethanolic extract on weight and body fat loss: a randomized,double-blind,placebo-controlled clinical trial

Food Science and Biotechnology - Steamed ginger ethanolic extract (SGE) is a product with a high 6-shogaol contents and is thought to be more potent than other ginger products. We conducted a...     

Effects of inorganic nitrate and nitrite consumption on cognitive function and cerebral blood flow: A systematic review and meta-analysis of randomized clinical trials

ABSTRACT

We conducted a systematic review and meta-analysis of randomized clinical trials examining the effect of inorganic nitrate or nitrite supplementation on cognitive function (CF) and cerebral blood flow (CBF). Two databases (PubMed, Embase) were searched for articles from inception until May 2017. Inclusion criteria were: randomized clinical trials; participants >18 years old; trials comparing a nitrate/nitrite intervention with a control. Thirteen and nine trials were included in the meta-analysis to assess CF and CBF, respectively. Random-effects models were used and the effect size described as standardized mean differences (SMDs). A total of 297 participants (median of 23 per trial) were included for CF; 163 participants (median of 16 per trial) were included for CBF. Nitrate/nitrite supplementation did not influence CF (SMD +0.06, 95% CI: -0.06, 0.18, P = 0.32) or CBF under resting (SMD +0.14, 95% CI: -0.13, 0.41, P = 0.31), or stimulated conditions (SMD + 0.23, 95% CI: -0.11, 0.56, P = 0.19). The meta-regression showed an inverse association between duration of the intervention and CBF (P = 0.02) but no influence of age, BMI or dose (P < 0.05). Nitrate and nitrite supplementation did not modify CBF or CF. Further trials employing larger samples sizes and interventions with longer duration are warranted.