Effect of carnitine supplementation on quality of life: a GRADE-assessed systematic review and meta-analysis of randomized controlled trials

Abstract

The quality of life (QoL) is a multidimensional concept that its enhancement is a key goal in clinical and public health interventions. Evidence for the effect of carnitine on QoL is still contradictory. Therefore, the present study aims to systematically review the current evidence from randomized controlled clinical trials (RCTs) and quantify the effect through a meta-analysis. Online databases were searched for relevant RCTs published until 9th November 2025, without any restrictions on publication date or language. The random-effect model was carried out to calculate effect size (Hedges`s g) from extracted mean change values and standard deviations (SD) of RCTs. Pre-planned subgroup analyses were conducted based on region, target population, mean age and BMI, and dose, formulation, and duration of intervention. Screening the database search results led to find 20 eligible RCTs with 21 study arms including 1878 participants. Results indicated that the carnitine supplementation could improve general health (Hedges’ g = 1.00, 95% CI: 0.33, 1.68), bodily pain (Hedges’ g = 0.83, 95% CI: 0.15, 1.50), vitality (Hedges’ g = 0.81, 95% CI: 0.32, 1.30), and social functioning (Hedges’ g = 0.72, 95% CI: 0.31, 1.13). Lower effects were observed for emotional functioning and global QoL. This is while, no significant effect was observed for mental health and physical functioning. Subgroup analyses indicated the dosage and formulation of intervention, target population, and region could possibly affect the observed results. Sensitivity analyses confirmed the robustness of findings, though substantial residual heterogeneity highlights variability in measurement instruments and study designs. Carnitine supplementation especially when tailored by formulation and dose appears to enhance multiple aspects of QoL, particularly bodily pain, general health, vitality, and social functioning. Clinicians should individualize supplementation strategies. Large, well-designed RCTs that evaluate dose, duration, formulation, and long-term outcomes are proposed to refine clinical recommendations. This systematic review was registered in PROSPERO (CRD420251162350).

The authors' abstract, as published at the source. Health and Quality of Life Outcomes, 2026 · DOI ↗