The effect of L-carnitine supplementation on lipid profile in adults: an umbrella meta-analysis on interventional meta-analyses

IntroductionPrevious meta-analyses investigating the therapeutic effects of L-carnitine on lipid profiles have demonstrated inconsistent results. The present umbrella meta-analysis aimed to investigate the impact of efficacy of L-carnitine on lipid profiles in adults.MethodsDatabases including PubMed, Scopus, and Embase, Web of Science, and Google Scholar were searched up to June 2023. Meta-analysis was performed using a random-effects model.ResultsOur results from thirteen meta-analyses indicated that L-carnitine supplementation significantly total cholesterol (TC) (ES = −1.05 mg/dL, 95% CI: −1.71, −0.39; p = 0.002), triglycerides (TG) (ES = −2.51 mg/dL; 95% CI: −3.62, −1.39, p < 0.001), and low-density lipoprotein-cholesterol (LDL-C) (ES = −4.81 mg/dL; 95% CI: −6.04, −3.59; p < 0.001). It also increased high-density lipoprotein-cholesterol (HDL-C) (ES: 0.66 mg/dL, 95% CI: 0.20, 1.12, p = 0.005) levels.ConclusionThe present umbrella meta-analysis suggests supplementation with L-carnitine in a dosage of more than 2 g/day can improve lipid profile. Thus, L-carnitine supplementation can be recommended as an adjuvant anti-hyperlipidemic agent

Synbiotic as an adjunctive agent can be useful in the management of hyperglycemia in adults: An umbrella review and meta-research of meta-analysis studies

Background: The available evidence about the possible effects of synbiotics on glycemic indices is not conclusive. In this regard, an umbrella meta-analysis was conducted with the aim of providing a better estimate of the overall effects of synbiotic supplementation on glycemic indices. Methods: The following international databases were systematically searched until January 2022: PubMed, Scopus, EMBASE, Web of Science, and Google Scholar. Results: A meta-analysis of 13 studies revealed a significant decreases in fasting blood sugar (FBS) (ES = -0.40, 95 % CI: −0.64, −0.15; p = 0.002, I2 = 69.2 %, p < 0.001), HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) (ES = -0.55; 95 % CI: −0.79, −0.30, p < 0.001, I2 = 48.4 %, p = 0.042), and insulin (ES = -1.58; 95 % CI:-2.50, −0.67; p < 0.001, I2 = 95.0 %, p < 0.001) following synbiotic supplementation. Conclusion: The current umbrella of meta-analyses suggests that synbiotic supplementation can improve FBS, HOMA-IR, and insulin levels. Overall, synbiotics can be recommended as an adjunctive anti-hyperglycemic agent

Can omega-3 fatty acids and vitamin E co-supplementation affect obesity indices?

Background: Studies have shown that vitamin E as an antioxidant protects omega-3 fatty acids (FAs) from oxidation. Several studies have evaluated the effect of omega-3 FAs and vitamin E co-supplementation on obesity indices; however, the results are inconsistent. The present systematic review and meta-analysis was conducted to address the role of omega-3 FAs plus vitamin E on obesity indices. Methods: Cochrane Library, PubMed, Scopus, Embase, and Web of Science databases were searched up to February 2022. Among all of the qualified studies, 10 articles were selected. The effect size was presented as weighted mean difference (WMD) and 95% confidence interval (CI). Fixed-effects model was employed to perform meta-analysis. Subgroup analysis and publication bias assessment were carried out. Results: Ten eligible randomized controlled trials comprising 558 participants were included. The average dose of omega-3 FAs and vitamin E co-supplementation in studies was 1000–4000 mg/day and 400 IU, respectively. Intervention duration varied from 6 to 16 weeks. There was no significant effect of omega-3 and vitamin E co-supplementation on body weight (BW) (WMD=0.14 kg; 95% CI: −0.13 to 0.42; p=0.297), and body mass index (BMI) (WMD=0.08, 95% CI: −0.01 to 0.16, p=0.073). However, subgroup analysis showed that it might increase BMI in women over 50 years and if the intervention lasted more than 8 weeks. Conclusion: There was no significant impact of combined omega-3 FAs and vitamin E supplementation on BW and BMI; however, it should be noted that the intervention has an increasing impact when supplementation duration was &gt;8 weeks and in individuals with type 2 diabetes mellitus, &gt;50 years old, and BMI&gt;25 kg/m2

Can resveratrol supplementation affect biomarkers of inflammation and oxidative stress? An umbrella meta-analysis

Several meta-analyses exist in supporting the positive effects of resveratrol on inflammatory and oxidative stress biomarkers; however, the finding of some studies is inconsistent. Therefore, the objective of the current study was to investigate the effects of resveratrol on inflammatory and oxidative stress biomarkers in adults. Up until April 2022, we conducted a thorough and systematic search in PubMed, Scopus, Web of Science, Embase, and Google Scholar. Our results from 15 meta-analyses indicated that the resveratrol supplementation meaningfully decrease serum CRP (ES = −0.38, 95 % CI: −0.47, −0.30; p < 0.001) and TNF-α (ES = −0.32; 95 % CI: −0.54, −0.11; p = 0.004). However, the effect of resveratrol on IL-6, TAC, GPx, and SOD activity was not significant. The current umbrella meta-analysis supports the alleviating effects of resveratrol on inflammatory markers but does not suggest any beneficial effect on oxidative stress biomarkers. Therefore, to support this evidence, larger and well-designed trials are required

Curcumin supplementation contributes to relieving anthropometric and glycemic indices, as an adjunct therapy: A meta-research review of meta-analyses

Background: Curcumin, a natural polyphenolic compound, can affect anthropometric and glycemic indices; however, the findings of existing meta-analyses are controversial. Study design: The current umbrella meta-analysis was performed among present systematic reviews and meta-analyses to investigate the effect of curcumin supplementation on anthropometric and glycemic indices. Methods: A comprehensive systematic search was performed on Embase, PubMed, WOS, Scopus, and Cochrane Library to obtain peer-reviewed papers published before 30/November/2021. meta-analysis was conducted using the random-effects model. Results: 12 meta-analyses were included in the current study. Our results have revealed that the curcumin supplementation can significantly decrease body mass index (BMI) (ES: −0.26; 95 % CI: −0.38, −0.14, p < 0.001; I2 = 0.0 %, P = 0.842), body weight (BW) (ES: −0.55; 95 % CI: −0.99, −0.12, p = 0.013; I2 = 81.1 %, p < 0.001), waist circumference (WC) (ES: −0.66; 95 % CI: −1.23, −0.09, p = 0.023; I2 = 72.4 %, p = 0.003), fasting blood sugar (FBS) (ES: −1.63; 95 % CI: −2.36, −0.89, p < 0.001; I2 = 88.4 %, p < 0.001), homeostasis model assessment-estimated insulin resistance (HOMA-IR) (ES: −0.38; 95 % CI: −0.48, −0.28, p < 0.001;I2 = 35.9 %, p = 0.142), hemoglobin A1c (HbA1c) (ES: −0.44; 95 % CI: −0.67, −0.21, p < 0.001;I2 = 65.0 %, p = 0.014), and insulin (ES: −0.86; 95 % CI: −1.52, −0.21, p = 0.010; I2 = 92.5 %, p < 0.001). Conclusion: These findings recommend curcumin supplementation as a favorable intervention to improve anthropometric and glycemic indices