The influence of fasting and energy-restricted diets on leptin and adiponectin levels in humans: A systematic review and meta-analysis.

BACKGROUND & AIMS: Fasting and energy-restricted diets have been evaluated in several studies as a means of improving cardiometabolic biomarkers related to body fat loss. However, further investigation is required to understand potential alterations of leptin and adiponectin concentrations. Thus, we performed a systematic review and meta-analysis to derive a more precise estimate of the influence of fasting and energy-restricted diets on leptin and adiponectin levels in humans, as well as to detect potential sources of heterogeneity in the available literature. METHODS: A comprehensive systematic search was performed in Web of Science, PubMed/MEDLINE, Cochrane, SCOPUS and Embase from inception until June 2019. All clinical trials investigating the effects of fasting and energy-restricted diets on leptin and adiponectin in adults were included. RESULTS: Twelve studies containing 17 arms and a total of 495 individuals (intervention = 249, control = 246) reported changes in serum leptin concentrations, and 10 studies containing 12 arms with a total of 438 individuals (intervention = 222, control = 216) reported changes in serum adiponectin concentrations. The combined effect sizes suggested a significant effect of fasting and energy-restricted diets on leptin concentrations (WMD: -3.690 ng/ml, 95% CI: -5.190, -2.190, p ≤ 0.001; I2 = 84.9%). However, no significant effect of fasting and energy-restricted diets on adiponectin concentrations was found (WMD: -159.520 ng/ml, 95% CI: -689.491, 370.451, p = 0.555; I2 = 74.2%). Stratified analyses showed that energy-restricted regimens significantly increased adiponectin (WMD: 554.129 ng/ml, 95% CI: 150.295, 957.964; I2 = 0.0%). In addition, subsequent subgroup analyses revealed that energy restriction, to ≤50% normal required daily energy intake, resulted in significantly reduced concentrations of leptin (WMD: -4.199 ng/ml, 95% CI: -7.279, -1.118; I2 = 83.9%) and significantly increased concentrations of adiponectin (WMD: 524.04 ng/ml, 95% CI: 115.618, 932.469: I2 = 0.0%). CONCLUSION: Fasting and energy-restricted diets elicit significant reductions in serum leptin concentrations. Increases in adiponectin may also be observed when energy intake is ≤50% of normal requirements, although limited data preclude definitive conclusions on this point.

Effects of the Dietary Approaches to Stop Hypertension (DASH) on Pregnancy/Neonatal Outcomes and Maternal Glycemic Control: A Systematic Review and Meta-analysis of Randomized Clinical Trials.

BACKGROUND & OBJECTIVE: No systematic review to date has appraised the impact of the Dietary Approaches to Stop Hypertension (DASH) eating plan on maternal glycemic control and pregnancy outcomes. Thus, we conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) to ascertain whether the DASH diet in pregnant women ameliorates their glycemic control and neonatal outcomes when compared to standard diets. METHODS: We performed a comprehensive systematic review and meta-analysis of RCTs on PubMed/MEDLINE, Web of Science, SCOPUS, and Embase from the inception until October 2019. RESULTS: Six studies met the eligibility criteria and were included in the quantitative meta-analysis. The pregnant women had cardiometabolic disorders such as gestational diabetes, obesity, and hypertension. The meta-analysis suggested a significant effect of DASH diet on fasting plasma levels of glucose (WMD = -6.239 mg/dl; 95% CI: -11.915, -0.563, p = 0.031), but not for the homeostasis model assessment of insulin resistance (WMD = -1.038; 95% CI: -2.704, 0.627, p = 0.22). Following the DASH diet during pregnancy decreased the risk of gestational preeclampsia (RR = 0.667; 95% CI: 0.451, 0.987, p = 0.043), macrosomia (birth weight >4000 g) (RR = 0.294; 95% CI: 0.120, 0.721, p = 0.043), and large for gestational age (RR = 0.452; 95% CI: 0.211, 0.969, p = 0.041). Consuming DASH diet during pregnancy neither increased nor decreased the risk of cesarean section, polyhydramnios, preterm birth (<37 weeks), and small for gestational age. The mean newborn head circumference (cm) (WMD = -0.807; 95% CI: -1.283, -0.331, p = 0.001) and ponderal index (kg/m3) (RR = -0.396; 95% CI: -0.441, -0.350, p = 0.000) in the group receiving the DASH diet were lower than in the control group. CONCLUSION: The adherence of pregnant women with cardiometabolic disorders to DASH eating pattern has a significant effect on decreasing fasting plasma glucose levels, ponderal index, incidence of preeclampsia, fetal macrosomia, large for gestational age, and newborn head circumference.

The effects of tocotrienol supplementation on lipid profile: A meta-analysis of randomized controlled trials.

BACKGROUND & OBJECTIVE: Tocotrienol supplementation has been emerged as a potent candidate for the treatment of dyslipidemia. In the present study, a systematic review and meta-analysis of randomized controlled trials was performed with the aim of examining the effects of tocotrienol supplementation on the lipid profile. METHODS: Four databases (Scopus, PubMed/Medline, Web of Science and Embase) were used to accomplish the literature search up to November 2019. Clinical trials encompassing the impact of tocotrienol supplementation on lipid profile were extracted regardless of clinical condition, with studies included involving only adults patients. RESULTS: A total of 15 articles with 20 arms were eligible and included in the meta-analysis to estimate the pooled effect size. Overall results showed a significant effect of tocotrienol supplementation on increasing high-density lipoprotein cholesterol (HDL-C) levels (weight mean difference (WMD): 0.146 mmol/L, I2 = 85.9%) and a non-significant influence on total cholesterol (TC) (WMD: 0.010 mmol/L, I2 = 64.5%), low-density lipoprotein cholesterol (LDL-C) (WMD: 0.095 mmol/L, I2 = 87.4%), and triglycerides (TG) (WMD: -0.112 mmol/L, I2 = 67.4%) levels. Increment in HDL-C levels was significant greater for the tocotrienol dosage ≥ 200 mg/d (WMD: 0.202 mmol/L) and ≤8 weeks (WMD: 0.278 mmol/L). Moreover, studies that investigated tocotrienol dose ≥200 mg had no heterogeneity, while showing a significant decrease in TG levels (WMD: -0.177 mmol/L). CONCLUSION: The present meta-analysis demonstrated that supplementing with tocotrienols does not decrease the concentrations of LDL-C, TC and TG. However, tocotrienol supplementation was considered a candidate for increasing HDL-C levels.

Effects of green coffee bean extract on C-reactive protein levels: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND & OBJECTIVE: The effects of green coffee bean extract (GCBE) supplementation on inflammatory biomarkers have been widely spread. The purpose of this article was to assess the impact of GCBE supplementation on C-reactive protein (CRP) levels. METHODS: The literature search was performed in four databases (Scopus, PubMed, the Cochrane Library, and Google Scholar) to identify studies that examined the influence of GCBE supplementation on CRP levels up to August 2019. Mean and standard deviation (SD) of the outcomes were used to estimate the weight mean difference (WMD) between intervention and control groups for the follow-up period. RESULTS: Five (5) studies, with 6 arms, reported CRP as an outcome. Statistically, the use of GCBE supplements resulted in a significant change in CRP levels (WMD: -0.017 mg/dL, 95 % CI: -0.032, -0.003, p = 0.018), whose overall findings were obtained from random-effects model. In addition, a significantly greater reduction in CRP was noted for studies with doses of GCBE supplements ≥ 1000 mg/d (WMD: -0.015 mg/dL, 95 % CI: -0.020, -0.010, p < 0.000), length of intervention < 4 weeks (WMD: -0.015 mg/dL, 95 % CI: -0.020, -0.010, p < 0.001), and for non-healthy subjects (WMD: -0.019 mg/dL, 95 % CI: -0.027, -0.011, p < 0.001). Dyslipidemia, hypertension and non-alcoholic fatty liver disease were the ailments of the studies that encompassed non-healthy patients. CONCLUSIONS: This meta-analysis shows that the use of GCBE supplements resulted in a statistical decrease in CRP levels, mainly for non-healthy subjects. However, due to the limited number of studies, further randomized clinical trials are crucial in this regard.

The effects of dehydroepiandrosterone (DHEA) supplementation on body composition and blood pressure: A meta-analysis of randomized clinical trials.

Dehydroepiandrosterone (DHEA) supplementation has been anecdotally considered as a tool to improve body composition and health status. We aimed to verify the impact of DHEA supplementation on traditional measurements of body composition and blood pressure (BP) due to their clinical applicability. A meta-analysis of randomized clinical trials was conducted based on the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Regarding anthropometric characteristics, DHEA supplementation did not change body weight (weighted mean difference (WMD): -0.16 kg, 95% CI: -1.02 to 0.70, p = 0.72) or body mass index (WMD: -0.18 kg/m2, 95% CI: -0.48 to 0.12, p = 0.24), but increased lean body mass (WMD: 0.45 kg, 95% CI: 0.15 to 0.75, p = 0.004) and decreased fat mass (WMD: -0.85%, 95% CI: -1.18 to -0.51, p = 0.000), when compared to control groups. Neither systolic (WMD: 0.98 mm Hg, 95% CI: -2.31 to 4.29, p = 0.56) nor diastolic BP were significantly changed (WMD: -1.62 mm Hg, 95% CI: -5.49 to 2.24, p = 0.49). Our findings demonstrate that DHEA supplementation increased lean body mass and decreased fat mass, but debate persists when translating the results into clinical benefit. Lastly, DHEA supplementation had a neutral effect on BP.

Effects of dehydroepiandrosterone (DHEA) supplementation on the lipid profile: A systematic review and dose-response meta-analysis of randomized controlled trials.

BACKGROUND AND AIMS: Dehydroepiandrosterone (DHEA) supplementation has gained attention in individuals with adrenal insufficiency, and as a tool for increasing androgens and estrogens whereby is proposed to improve the accretion of muscle and bone mass. However, DHEA supplementation has demonstrated negative effects on the lipid profile and, thus, we aimed to analyze the body of evidence in this regard. METHODS AND RESULTS: A systematic review and dose-response meta-analysis of randomized controlled trials (RCTs) was performed employing in Scopus, PubMed/Medline, Web of Science, Embase and Google Scholar, then including relevant articles that addressed the effects of DHEA supplementation on the lipid profile, up to February 2020. Combined findings were generated from 23 eligible articles. Hence, total cholesterol (TC) (weighted mean difference (WMD): -3.5 mg/dl, 95% confidence interval (CI): -8.5 to 1.6)), low-density lipoprotein-cholesterol (LDL-C) (WMD: 0.34 mg/dl, 95% CI: -3 to 3.7) and triglycerides (TG) levels (WMD: -2.85 mg/dl, 95% CI: -9.3 to 3.6) did not alter in DHEA group compared to the control, but HDL-C levels significantly reduced in DHEA group (WMD: -3.1 mg/dl, 95% CI: -4.9 to -1.3). In addition, a significant reduction in HDL-C values was observed in studies comprising women (WMD: -5.1 mg/dl, 95% CI: -7.2 to -3) but not in males (WMD: 0.13 mg/dl, 95% CI: -1.4 to 1.7). CONCLUSIONS: Overall, supplementation with DHEA did not change circulating values of TC, LDL-C and TG, whereas it may decrease HDL-C levels. Further long-term RCTs are required to investigate the effects of DHEA particularly on major adverse cardiac events.

Effects of walnut intake on blood pressure: A systematic review and meta-analysis of randomized controlled trials.

The impact of walnuts on blood pressure (BP) is not a well-established fact. Although several studies have assessed the effects of walnut consumption on BP, results are conflicting. Thus, we examined the effects of walnut doses and length of supplementation on BP. Biomedical databases were searched for published trials that compared walnut-enhanced diet to control diet. Eighteen trials met eligibility criteria (n = 1,799). Overall, walnut consumption neither did alter SBP (weighted mean difference [WMD]: 0.08 mmHg; 95% CI: -0.69, 0.85) nor DBP (WMD: 0.08 CI: -0.26, 0.42). In subgroup analyses, walnut ingestion ≤40 g was statistically correlated with reduction in SBP (WMD: -0.53 mmHg, 95% CI: -0.79, -0.26) and DBP (WMD: -0.191 mmHg, 95% CI: -0.384, -0.034). Moreover, the length of intervention ≥8 weeks was linked to a significant reduction in SBP (WMD: -1.18 mmHg, 95% CI: -1.30, -1.06). Following dose-response evaluation, walnut intake significantly changed SBP (p = .015) and DBP (p = .026) through a nonlinear fashion at walnut dose up to 40 g/d. Nevertheless, these statistical results cannot be translated into clinical practice, once the changes expressed as WMD are slight taking into consideration the absolute values of BP categories. In conclusion, this meta-analysis does not support walnut consumption as a BP-lowering strategy.

Effects of intermittent fasting and energy-restricted diets on lipid profile: A systematic review and meta-analysis.

OBJECTIVES: To the best of our knowledge, no systematic review and meta-analysis has evaluated the cholesterol-lowering effects of intermittent fasting (IF) and energy-restricted diets (ERD) compared with control groups. The aim of this review and meta-analysis was to summarize the effects of controlled clinical trials examining the influence of IF and ERD on lipid profiles. METHODS: A systematic review of four independent databases (PubMed/Medline, Scopus, Web of Science and Google Scholar) was performed to identify clinical trials reporting the effects of IF or ERD, relative to non-diet controls, on lipid profiles in humans. A random-effects model, employing the method of DerSimonian and Laird, was used to evaluate effect sizes, and results were expressed as weighted mean difference (WMD) and 95% confidence intervals (CIs). Heterogeneity between studies was calculated using Higgins I2, with values ≥50% considered to represent high heterogeneity. Subgroup analyses were performed to examine the influence of intervention type, baseline lipid concentrations, degree of energy deficit, sex, health status, and intervention duration. RESULTS: For the outcomes of low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triacylglycerols (TG), there were 34, 33, 35, and 33 studies meeting all inclusion criteria, respectively. Overall, results from the random-effects model indicated that IF and ERD interventions resulted significant changes in TC (WMD, -6.93 mg/dL; 95% CI, -10.18 to -3.67; P < 0.001; I2 = 78.2%), LDL-C (WMD, -6.16 mg/dL; 95% CI, -8.42 to -3.90; P ˂ 0.001; I2 = 52%), and TG concentrations (WMD, -6.46 mg/dL; 95% CI, -10.64 to -2.27; P = 0.002; I2 = 61%). HDL-C concentrations did not change significantly after IF or ERD (WMD, 0.50 mg/dL; 95% CI, -0.69 to 1.70; P = 0.411; I2 = 80%). Subgroup analyses indicated potentially differential effects between subgroups for one or more lipid parameters in the majority of analyses. CONCLUSIONS: Relative to a non-diet control, IF and ERD are effective for the improvement of circulating TC, LDL-C, and TG concentrations, but have no meaningful effects on HDL-C concentration. These effects are influenced by several factors that may inform clinical practice and future research. The present results suggest that these dietary practices are a means of enhancing the lipid profile in humans.

Effects of walnut intake on anthropometric characteristics: A systematic review and dose-response meta-analysis of randomized controlled trials.

BACKGROUND & OBJECTIVE: Effects of walnut intake on anthropometric measurements have been inconsistent among clinical studies. Thus, we conducted a meta-analysis of randomized clinical trials (RCTs) to evaluate and quantify the effects of walnut intake on anthropometric characteristics. METHODS: We carried out a systematic search of all available RCTs up to June 2019 in the following electronic databases: PubMed, Scopus, Web of Science and Google Scholar. Pooled weight mean difference (WMD) of the included studies was estimated using random-effects model. RESULTS: A total of 27 articles were included in this meta-analysis, with walnuts dosage ranging from 15 to 108 g/d for 2 wk to 2 y. Overall, interventions with walnut intake did not alter waist circumference (WC) (WMD: -0.193 cm, 95 % CI: -1.03, 0.64, p = 0.651), body weight (BW) (0.083 kg, 95 % CI: -0.032, 0.198, p = 0.159), body mass index (BMI) (WMD: -0.40 kg/m,295 % CI: -0.244, 0.164, p = 0.703), and fat mass (FM) (WMD: 0.28 %, 95 % CI: -0.49, 1.06, p = 0.476). Following dose-response evaluation, reduced BW (Coef.= -1.62, p = 0.001), BMI (Coef.= -1.24, p = 0.041) and WC (Coef.= -5.39, p = 0.038) were significantly observed through walnut intake up to 35 g/day. However, the number of studies can be limited as to the individual analysis of the measures through the dose-response fashion. CONCLUSIONS: Overall, results from this meta-analysis suggest that interventions with walnut intake does not alter BW, BMI, FM, and WC. To date, there is no discernible evidence to support walnut intake for improving anthropometric indicators of weight loss.

Impact of dehydroepianrosterone (DHEA) supplementation on serum levels of insulin-like growth factor 1 (IGF-1): A dose-response meta-analysis of randomized controlled trials.

BACKGROUND AND AIM: Inconsistencies exist with regard to the influence of dehydroepiandrosterone (DHEA) supplementation on insulin-like growth factor 1 (IGF-1) levels. The inconsistencies could be attributed to several factors, such as dosage, gender, and duration of intervention, among others. To address these inconsistencies, we conducted a systematic review and meta-analysis to combine findings from randomized controlled trials (RCTs) on this topic. METHODS: Electronic databases (Scopus, PubMed/Medline, Web of Science, Embase and Google Scholar) were searched for relevant literature published up to February 2020. RESULTS: Twenty-four qualified trials were included in this meta-analysis. It was found that serum IGF-1 levels were significantly increased in the DHEA group compared to the control (weighted mean differences (WMD): 16.36 ng/ml, 95% CI: 8.99, 23.74; p = .000). Subgroup analysis revealed that a statistically significant increase in serum IGF-1 levels was found only in women (WMD: 23.30 ng/ml, 95% CI: 13.75, 32.87); in participants who supplemented 50 mg/d DHEA (WMD: 15.75 ng/ml, 95% CI: 7.61, 23.89); in participants undergoing DHEA intervention for >12 weeks (WMD: 17.2 ng/ml, 95% CI: 8.02, 26.22); in participants without an underlying comorbidity (WMD: 19.11 ng/ml, 95% CI: 10.69, 27.53); and in participants over the age of 60 years (WMD: 19.79 ng/ml, 95% CI: 9.86, 29.72). CONCLUSION: DHEA supplementation may increase serum IGF-I levels especially in women and older subjects. However, further studies are warranted before DHEA can be recommended for clinical use.