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

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

Rahimlou M ，Asadi M ，Banaei Jahromi N ，Mansoori A ... -  《Clinical Nutrition ESPEN》

An updated systematic review and dose-response meta-analysis of the effects of α-lipoic acid supplementation on glycemic markers in adults.

This systematic review and dose-response meta-analysis was conducted to summarize data from available clinical trials on the effects of α-lipoic acid (ALA) supplementation on glycemic markers including glucose, hemoglobin A1c (HbA1c), insulin, homeostatic model assessment of insulin resistance (HOMA-IR), HOMA-β, and quantitative insulin check index in adults. A comprehensive literature search was conducted in the electronic databases of PubMed, Web of Science, ProQuest, Embase and SCOPUS from inception to February 2020. Among all of the eligible studies, 28 articles were selected. The weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated to evaluate the pooled effect size. Between-study heterogeneity was evaluated using Cochran's Q test and I2. Subgroup analysis was done to evaluate the potential sources of heterogeneity. The dose-response relationship was evaluated using fractional polynomial modeling. Twenty eight eligible studies with a total sample size of 1,016 participants were included in the current meta-analysis. The findings of the meta-analysis showed that ALA supplementation significantly reduced insulin (WMD: -0.64; CI: -1.287 to 0.004, P = .04), HOMA-IR (WMD: -0.48; 95% CI: -0.79 to -0.16; P = .002). No change in glucose or HbA1C was reported. Moreover, the effect of ALA on insulin was duration-dependent (Pnon-linearity = 0.04). No evidence of departure from linearity was observed between dose and duration of the ALA supplementation on other markers. The subgrouping revealed that ALA dosage and duration of ALA supplementation, health status of participants, geographic locations and the studies' quality are possible sources of heterogeneity. In summary, ALA supplementation improves serum insulin and insulin resistance in a two-class and duration dependent non-linear analysis.

Mahmoudi-Nezhad M ，Vajdi M ，Farhangi MA 《-》

An updated systematic review and dose-response meta-analysis of the randomized controlled trials on the effects of alpha-lipoic acid supplementation on inflammatory biomarkers.

Vajdi M ，Mahmoudi-Nezhad M ，Farhangi MA 《INTERNATIONAL JOURNAL FOR VITAMIN AND NUTRITION RESEARCH》

Effects of l-arginine supplementation on glycemic profile: Evidence from a systematic review and meta-analysis of clinical trials.

The effects of l-arginine supplementation on indices of glycemic control and the role of many factors influencing this intervention have been controversial in clinical trials. This meta-analysis was performed to assess the effects of l-arginine supplementation on indices of glycemic control, including fasting blood glucose (FBG), hemoglobin A1c (HbA1c), serum insulin and homeostatic model assessment of insulin resistance (HOMA-IR) levels in randomized controlled trials (RCTs). This study conducted a systematic review of RCTs published in PubMed, Scopus, Web of Science, Cochrane Library and Embase, up to 5 May, 2018. Studies were included in this meta-analysis if they were RCTs with parallel design and reported sufficient data on participants before and after intervention, and outcomes of glycemic profile parameters in both the arginine supplementation and control groups. The screening of titles and abstracts was performed independently by two reviewers. Selected articles were considered if they met the study's inclusion criteria. The quality of included studies was assessed by using the Cochrane Collaboration modified tool. From 710 articles retrieved in the initial search, only 10 trials were suitable for pooling the effects of arginine supplementation on serum glucose, insulin, HOMA-IR and HbA1c levels, with effect sizes of nine, eight, five and five, respectively. Pooled random-effect analysis revealed that l-arginine supplementation could significantly decrease FBG level (weighted mean difference [WMD]: 3.35 mg/dL; 95% confidence interval [CI] = [-6.55, -0.16]; P = 0.04) and serum insulin level (WMD: -2.19 μIU/mL; 95% CI = [-3.70, -0.67]; P = 0.005). However, the effects of l-arginine supplementation on HOMA-IR and HbA1c were not significant. Results of subgroup analysis showed that supplementation with l-arginine could significantly decrease serum insulin levels when the dosage of l-arginine is > 6.5 g/d (WMD: -3.49 μIU/mL; 95% CI = [-5.59, -1.38]; P = 0.001), when the duration of supplementation is ≤ 12.8 weeks (WMD: -3.76; 95% CI = [-6.50, -0.98]; P = 0.008), when the participants are not diabetic patients (WMD: -2.54 μIU/mL; 95% CI = [-4.50, -0.50]; P = 0.01) and when the baseline serum level of insulin was > 20 μIU/mL (WMD: -3.98; 95% CI = [-6.31, -1.65]; P = 0.001). Although the results of this study confirmed that supplementation with l-arginine could have significant effects on some glycemic profile indices of participants in clinical trials, the clinical importance of this reduction may not be meaningful.

Yousefi Rad E ，Nazarian B ，Saboori S ，Falahi E ，Hekmatdoost A ... -  《Journal of Integrative Medicine-JIM》

Selenium supplementation effect on glycemic control: A GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trials.

Vajdi M ，Hassanizadeh S ，Gholami Z ，Bagherniya M ... -  《-》