Effects of l-Carnitine Supplementation on Serum Inflammatory Factors and Matrix Metalloproteinase Enzymes in Females with Knee Osteoarthritis: A Randomized, Double-Blind, Placebo-Controlled Pilot Study

J Am Coll Nutr. Sep-Oct 2016;35(7):597-603. doi: 10.1080/07315724.2015.1068139. Epub 2016 Mar 2.


Objective: Considering the importance of inflammation in the pathogenesis of osteoarthritis (OA) and induction of pain, this study was aimed to investigate the effect of L-carnitine supplementation on serum inflammatory mediators and OA-associated pain in females with knee OA.

Methods: In this clinical trial, 72 females with mild to moderate knee osteoarthritis started the study, divided into 2 groups to receive 750 mg/day L-carnitine (n = 36) or placebo (n = 36) for 8 weeks. Serum levels of Interleukine-1β (IL-1β), high-sensitivity C-reactive protein (hs-CRP), matrix metalloproteinases (MMPs)-1 and -13, and visual analog scale (VAS) for pain were assessed before and after supplementation. Data were analyzed by t test, Wilcoxon signed rank test, Mann-Whitney U test, and analysis of covariance.

Results: Only 69 patients (33 in the L-carnitine group and 36 in the placebo group) completed the study. L-Carnitine supplementation decreased serum IL-1β and MMP-1 levels significantly (p = 0.001 and p = 0.021, respectively); however, serum hs-CRP and MMP-13 levels did not change significantly (p > 0.05). In the placebo group, serum IL-1β levels increased significantly (p = 0.011), whereas other studied biomarkers did not change significantly. The mean VAS score decreased significantly in the L-carnitine and placebo groups by 52.67% and 21.82%, respectively (p < 0.001). Significant differences were only observed between the 2 groups in serum IL-1β (p < 0.001) and MMP-1 (p = 0.006) levels and mean VAS score (p = 0.002) after adjusting for baseline values and covariates.

Conclusion: Despite observed beneficial effects of short-term supplementation of L-carnitine in decreasing serum inflammatory mediators and improving pain in knee OA patients, further studies are needed to achieve concise conclusions.

Keywords: L-carnitine; inflammation; matrix metalloproteinase; osteoarthritis.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Inflammatory Agents*
  • Biomarkers / blood*
  • C-Reactive Protein / analysis
  • Carnitine / administration & dosage*
  • Dietary Supplements
  • Double-Blind Method
  • Female
  • Humans
  • Inflammation / blood*
  • Interleukin-1beta / blood
  • Matrix Metalloproteinase 1 / blood
  • Matrix Metalloproteinase 13 / blood
  • Matrix Metalloproteinases / blood*
  • Middle Aged
  • Osteoarthritis, Knee / blood
  • Osteoarthritis, Knee / drug therapy*
  • Pilot Projects
  • Placebos


  • Anti-Inflammatory Agents
  • Biomarkers
  • Interleukin-1beta
  • Placebos
  • C-Reactive Protein
  • Matrix Metalloproteinase 13
  • Matrix Metalloproteinases
  • Matrix Metalloproteinase 1
  • Carnitine