Meta-Analysis Finds L-Carnitine Supplementation Reduces CV Risk Factors in Diabetic and Glucose Intolerant Patients

This meta-analysis revealed that L-carnitine supplementation significantly reduces levels of triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), fasting blood glucose (FBG), HbA1c, HOMA-IR, C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), as well as weight, body mass index (BMI), body fat percentage (BFP), and leptin in patients with diabetes and impaired glucose tolerance. However, no significant effects were observed on total cholesterol (TC), high-density lipoprotein (HDL), serum insulin, systolic blood pressure (SBP), diastolic blood pressure (DBP), apolipoprotein A (apo A), or apolipoprotein B (apo B) in these patients.

The findings were published online in Diabetology & Metabolic Syndrome on July 31, 2024.

L-carnitine is often touted for its potential benefits in enhancing exercise performance and weight management. However, its effects on cardiovascular health, particularly in diabetic and pre-diabetic populations, have been less clear. Therefore, Rezvan Gheysari, Shohada-E-Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran, and colleagues aimed to assess the effect of L-carnitine supplementation on CVD risk factors.

For this purpose, the researchers conducted a systematic literature search in PubMed, Web of Science, and Scopus until October 2022. The primary outcomes assessed included lipid profiles, insulin resistance, anthropometric measurements, leptin, serum glucose levels, blood pressure, and inflammatory markers. A random-effects model was used to calculate the pooled weighted mean difference (WMD).

The researchers reported the following findings:

• The study included 21 RCTs (n = 2900) with 21 effect sizes.
• L-carnitine supplementation had a significant effect on TG (WMD = − 13.50 mg/dl), LDL (WMD = − 12.66 mg/dl), HbA1c (WMD = -0.37%), FBG (WMD = − 6.24 mg/dl), HOMA-IR (WMD = -0.72), CRP (WMD = − 0.07 mg/dl), TNF-α (WMD = − 1.39 pg/ml), weight (WMD = − 1.58 kg), BFP (WMD = − 1.83), BMI (WMD = − 0.28 kg/m2), and leptin (WMD = − 2.21 ng/ml) in intervention, compared to the placebo group, in the pooled analysis.

The analysis also indicated that the optimal duration for L-carnitine supplementation to effectively reduce FBG, HbA1c, and HOMA-IR was approximately 50 weeks after initiation. It was noted that longer durations of supplementation (≥ 25 weeks) had a diminishing impact on weight.

"Given the significant risk of bias present in the majority of the included trials, further well-designed and comprehensive RCTs with larger sample sizes and robust analytical methods are needed to more accurately determine the influence of L-carnitine on cardiovascular disease (CVD) risk factors in individuals with diabetes and glucose intolerance," the researchers concluded.

Reference:

Gheysari, R., Nikbaf-Shandiz, M., Hosseini, A.M. et al. The effects of L-carnitine supplementation on cardiovascular risk factors in participants with impaired glucose tolerance and diabetes: a systematic review and dose–response meta-analysis. Diabetol Metab Syndr 16, 185 (2024). https://doi.org/10.1186/s13098-024-01415-8