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.

The influence of maternal vitamin D supplementation on infant vitamin D status: A systematic review and meta-analyses.

BACKGROUND: Inconsistencies exist with regard to effect of maternal vitamin D supplementation on infant vitamin D status. The inconsistencies could be attributed to numerous factors, such as duration of intervention and dosage, among others. In this work, we conducted a systematic review and meta-analysis to determine the influence of maternal vitamin D supplementation on infant vitamin D status. METHODS: A comprehensive systematic search was performed in Scopus, EMBASE, Web of Science, and PubMed/MEDLINE, by investigators, from database inception until November 2019, without using any restrictions. Weighted mean difference (WMD) with the 95 % CI was used for assessing the effects of maternal vitamin D supplementation on 25(OH) D levels in infants. RESULTS: Overall results from 14 studies revealed a non-significant effect of maternal vitamin D administration on the level of 25(OH) D in breastfeeding infants (WMD: -0.464 ng/mL, 95 % CI: -6.68 to 5.75, p = 0.884, I2 = 98 %). Subgroup analyses demonstrated that vitamin D supplementation dosage ≥2000 IU/day (WMD: 9 ng/mL, 95 % CI: 8.19, 9.82, I2 = 99 %) and intervention duration ≥20 weeks (WMD: 16.20 ng/mL, 95 % CI: 14.89, 17.50, I2 = 99 %) significantly increased 25(OH) D. CONCLUSIONS: The main results indicate a non-significant increase in infant vitamin D following maternal vitamin D supplementation. Additionally, vitamin D supplementation dosage ≥2000 IU/day and intervention duration ≥20 weeks significantly increased infant 25(OH) D.

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.

Walnut intake may increase circulating adiponectin and leptin levels but does not improve glycemic biomarkers: A systematic review and meta-analysis of randomized clinical trials.

BACKGROUND & OBJECTIVE: Walnut intake is considered a healthy dietary approach worldwide, particularly as a nutritional tool for the management of obesity and cardiometabolic disorders. Among these lines, leptin and adiponectin, as well as glycemic biomarkers, deserve further attention. We aimed to examine the impact of walnut intake on circulation levels of leptin and adiponectin through a systematic review and meta-analysis of randomized clinical trials (RCTs); secondarily, assessing the glycemic profile as well. METHODS: The literature search was implemented in four following databases: Web of Science, Scopus, PubMed/Medline, and Google Scholar, thus, determining studies that measured the effects of walnut consumption on adiponectin, leptin, and glycemic biomarkers levels from 2004 up to December 2019. RESULTS: Fourteen trials were include in the meta-analysis, with an intervention period ranging from 5 weeks to 12 months.Walnut intake increased leptin (weighted mean difference (WMD): 2.502 ng/mL; 95 % CI: 2.147-2.856, p < 0.001) and adiponectin (WMD: 0.440 ng/mL; 95 % CI: 0.323 to 0.557, p < 0.001) levels. Pertaining to glycemic biomarkers, neither overall analyses nor sub-analyses corroborated with changes in fasting blood glucose (WMD: 0.500 mg/dL, 95 % CI: -0.596, 1.596, p = 0.371), insulin (WMD: -0.21 mg/dL, 95 % CI: -0.67, 0.24, p = 0.367), and glycated hemoglobin (WMD: 0.004 mg/dL, 95 % CI: -0.041, 0.049, p = 0.870) concentrations. CONCLUSION: Walnut intake may increase leptin and adiponectin levels but does not improve glycemic biomarkers.

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.

The influence of green coffee bean extract supplementation on blood glucose levels: A systematic review and dose-response meta-analysis of randomized controlled trials.

Studies regarding the influence of green coffee extract (GCE) on blood glucose levels are conflicting. Thus, we sought to conduct a meta-analysis and systematic review of all available randomized controlled trials (RCTs) to quantify the effects of GCE and CGA intervention on blood glucose and insulin levels. We performed systematic online searches in Scopus, Web of science, and PubMed databases, from inception to July 2019. Data were combined analyzed using a random effects model (Der Simonian-Laird method) and reported as weighted mean differences (WMD). Ten trials reported the influences of GCE on FBS and insulin and were subsequently entered into the meta-analysis. Combined results highlighted that FBS was significantly altered after GCE consumption (WMD: -1.791 mg/dl, 95% CI -3.404, -0.177), with no significant heterogeneity among the studies (I2 = 35.0%, p = .128). However, overall results demonstrated that GCE administration did not result in any significant alteration in insulin levels (WMD: -0.925 µU/ml, 95% CI:-1.915, 0.064), with significant heterogeneity found across studies (I2 = 87.9%). In sub-group analysis, insulin levels were significantly reduced when GCE was supplemented in dosages of ≥400 mg/day (WMD:-1.942 mg/dl, 95% CI:-1.184, -0.975; I2 = 0.0%). The results of present study support the use of GCE for the enhancement of blood glucose, while subgroup analysis highlighted significant improvements in insulin levels when GCE is supplemented in doses ≥400 mg/day.

The influence of vitamin D supplementation on IGF-1 levels in humans: A systematic review and meta-analysis.

BACKGROUND: Inconsistencies exist with regard to influence of vitamin D supplementation on IGF-1 levels. The inconsistencies could be attributed to several factors, such as dosage and duration of intervention, among others. To address these inconsistencies, this study was conducted to determine the impact of vitamin D supplementation on IGF-1 levels through a systematic review and meta-analysis of randomized controlled trials (RCTs). METHODS: A comprehensive systematic search was carried out in PubMed/MEDLINE, Web of Science, SCOPUS and Embase for RCTs that investigated the impact of vitamin D intake on circulating IGF-1 levels from inception until June 2019. Weighted mean difference (WMD) with the 95 % CI were applied for estimating combined effect size. Subgroup analysis was performed to specify the source of heterogeneity among studies. RESULTS: Pooled results from eight studies demonstrated an overall non-significant increase in IGF-1 following vitamin D supplementation (WMD: 4 ng/ml, 95 % CI: -4 to 11). However, a significant degree of heterogeneity among studies was observed (I2 = 66 %). The subgroup analyses showed that vitamin D dosage of ≤1000 IU/day (WMD: 10 ng/ml) significantly increased IGF-1 compared to the vitamin D dosage of <1000 IU/day (WMD: -1 ng/ml). Moreover, intervention duration ≤12 weeks (WMD: 11 ng/ml) significantly increased IGF-1 compared to intervention duration <12 weeks (WMD: -3 ng/ml). In the epidemiological cohort study, participants under 60 years of age with a higher dietary vitamin D intake had significantly higher IGF-1 levels when compared to those with lower dietary vitamin D intake in second categories. CONCLUSION: The main results indicate a non-significant increase in IGF-1 following vitamin D supplementation. Additionally, vitamin D dosages of <1000 IU/day and intervention durations of <12 weeks significantly raised IGF-1 levels.