The effects of L-carnitine supplementation on lipid profiles in adults: A systematic review and dose-response meta-analysis

Background

We aimed to conduct this meta-analysis to systematically assess the effects of L-carnitine supplementation on levels of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), total cholesterol (TC), Apolipoprotein A (Apo A) and Apolipoprotein B (Apo B) in adults.

Methods

A systematic search was done in databases such as PubMed, ISI Web of Science, the Cochrane Library, and Scopus to find acceptable articles up to April 2023. Randomized controlled trials (RCTs) evaluating the effects of L-carnitine on lipid profiles in adults were included considering the specified inclusion and exclusion criteria.

Results

We included the 60 RCTs (n = 3933) with 64 effect sizes in this study. L-carnitine supplementation had a significant effect on TG (WMD= −10.33 mg/dl, P < 0.001), TC (WMD= −6.91 mg/dl, P = 0.032), LDL-C (WMD= −7.51 mg/dl, P < 0.001), HDL-C (WMD= 1.80 mg/dl, P = 0.007) in intervention, compared to a placebo group, in the pooled analysis. Moreover, we conducted the subgroup analyses that have shown L-carnitine supplementation had a reduction effect on TG in baseline ≥ 150 mg/dl, and in any trial duration (<12 and ≥12 weeks), intervention dose ≥ 2 g/day, in overweight (25–29.9 kg/m²) and obese (>30 kg/m²), in type ² diabetes and other health status. Also, L-carnitine significantly impacted TC in baseline ≥ 200 mg/dl, trial duration ≥ 12 weeks, intervention dose ≥ 2 g/day, obese (>30 kg/m²), and other health statuses.

Conclusions

Our results indicate L-carnitine significantly reduces the serum levels of TC, LDL-C, and TG and increases HDL-C, but it had no significant effect on the levels of apolipoproteins.