Alpha-lipoic acid on intermediate disease markers in overweight or obese adults: a systematic review and meta-analysis.

Abstract

Objectives: To evaluate the associations between alpha-lipoic acid (ALA) intake and intermediate disease markers in overweight or obese adults.

Design: Systematic review and meta-analysis.

Data sources: PubMed, EMBASE, Medline, APA PsycINFO, SocINDEX, CINAHL, SSRN, SocArXiv, PsyArXiv, medRxiv, and Google Scholar (from inception to October 2024).

Eligibility criteria: This study included English-language randomised controlled trials (RCTs) on adults (body mass index ≥25 kg/m²) to assess the impact of ALA on intermediate disease markers. Studies lacking outcome data, duplicates or inaccessible full texts were excluded.

Data extraction and synthesis: Paired reviewers independently extracted the data. We used frequentist meta-analysis to summarise the evidence, employing the DerSimonian and Laird estimator to account for heterogeneity across study designs, settings and measurement methods. Heterogeneity was assessed via the I² statistic with CIs and τ² values. The risk of bias was independently assessed by two reviewers according to the Cochrane Handbook, covering domains such as randomisation, blinding and data completeness. Publication bias was assessed using Begg's test, while funnel plots and Egger's test were applied to outcomes with 10 or more studies.

Results: This meta-analysis included 11 RCTs from an initial screening of 431 studies, encompassing a total of 704 adults. The meta-analysis results revealed no significant associations were detected between ALA supplementation and changes in intermediate disease markers, including triglyceride (TG) (standardised mean difference (SMD): -0.08, 95% CI: -0.24 to 0.09, p=0.36, I²=0.00%, τ²=0.00), total cholesterol (TC) (SMD: 0.08, 95% CI: -0.55 to 0.71, p=0.80, I²=87.50%, τ²=0.52), high-density lipoprotein cholesterol (HDL-C) (SMD: -0.05, 95% CI: -0.22 to 0.11, p=0.52, I²=0.00%, τ²=0.00), low-density lipoprotein cholesterol (LDL-C) (SMD: -0.13, 95% CI: -0.40 to 0.15, p=0.37, I²=0.00%, τ²=0.00), homeostasis model assessment of insulin resistance (HOMA-IR) (SMD: -0.23, 95% CI: -0.60 to 0.15, p=0.23, I²=26.20%, τ²=0.05) and fasting blood glucose (FBS) (SMD: 0.13, 95% CI: -0.16 to 0.41, p=0.39, I²=29.40%, τ²=0.04). According to the Grading of Recommendations Assessment, Development and Evaluation bias assessment approach, eight studies were rated as having low bias (grade A), and three studies were rated as having moderate bias (grade B). Begg's test indicated no evidence of publication bias.

Conclusions: No significant associations were detected between ALA intake and intermediate disease markers, including TG, TC, HDL-C, LDL-C, HOMA-IR and FBS levels, in overweight or obese adults. Further research is needed to explore the potential associations of ALA, especially in high-risk populations with metabolic disorders, by employing longer intervention durations, higher dosages and optimised formulations.

Prospero registration number: CRD42023450239.