Alpha lipoic acid promotes a healthy inflammatory response, meta-analysis shows
Highlights
- Meta-analysis of 11 randomized, controlled trials
- ALA supplementation ranges from 300 to 1,200 mg/day
- Study duration ranges from 2 weeks to 54 weeks
- ALA significantly decreases a high serum CRP level in adults without diabetes
Summary
This systematic review and meta-analysis was conducted to assess the effect of alpha-lipoic acid (ALA) supplementation on the serum level of C-reactive protein (CRP), a marker of inflammation, in controlled clinical trial studies.
A systematic search was carried out on clinical trial studies published in PubMed, ISI Web of Science, Cochrane Library and Scopus databases up to November 4, 2017. Inclusion criteria included randomized, controlled clinical trials of oral ALA supplementation with duration of more than one week, reporting mean or median values of CRP levels at pre- and post-intervention. Exclusion criteria included studies with multi-ingredient interventions, no control/placebo group, or insufficient data for CRP levels, or studies with case-control, cohort or cross-sectional designs.
Results are reported as the weighted mean difference (WMD) with 95% confidence intervals (CI) using a random effects model. Heterogeneity was assessed with I-squared (I2) and Cochrane’s Q tests. Publication bias and subgroup analyses were also performed.
A total of 11 studies published between 2007 and 2017 met the inclusion criteria and were included in the meta-analysis. These studies included 264 participants in supplementation groups and 287 in control groups. The duration of study interventions varied from 2 weeks to 54 weeks, and ALA dosages ranged from 300 to 1,200 g/day.
Results indicate ALA supplementation significantly decreased CRP level (WMD: -0.72 mg/l, 95% CI; -1.4, -0.04; P=.03) with a significant heterogeneity between the selected studies. Sub-group analysis showed ALA supplementation significantly reduced serum CRP level when the baseline CRP level was greater than 3 mg/l (WMD: -1.02 mg/l, 95% CI: -1.3, -0.73) and when trial duration was longer than 8 weeks (-0.99 mg/l, 95% CI: -1.29, -0.70). Results of subgroup analysis also showed that ALA supplementation could decrease CRP level only in non-diabetic patients (WMD: -1.02 mg/l, 95% CI: -1.31, -0.74).
These findings indicate that ALA supplementation (300 to 1,200 mg/day for at least 8 weeks) may offer clinical value to reduce serum CRP level, an inflammatory marker, in adults without diabetes.
