Backgrounds L-carnitine decreases oxidation and inflammation by reducing the fatty acid in plasma and using oxygen in ATP synthesis. As such, knee osteoarthritis (KOA) can be improved by reducing apoptotic chondrocytes. This study was designed to compare the effect of L-carnitine supplementation and low-calorie diet on improving KOA among obese women. We further investigated the effect of L- carnitine on improvement of KOA in obese women on low calorie diet. Methods To conduct the study, 76 obese women with KOA were randomly assigned into two low-calorie diet groups: the first received 1000 mg of LCG and the second took the placebo (PLG) (n = 38). Anthropometry indices, body composition, lipid profile, C-reactive Protein (CRP), Malondialdehyde (MDA), and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) were assessed at the baseline condition and after 12 weeks. Results The mean change of body mass index (BMI) (− 1.21 ± 0.84 vs. -0.79 ± 0.70; P = 0.02) and weight (− 2.76 ± 1.69 vs. -1.95 ± 1.73; P = 0.05) were significant in the LCG compared with the PLG. Likewise, LCG compared to the PLG showed insignificant improvement in waist circumference (WC) (− 5.65 ± 5.85 vs. -3.64 ± 3.37; P = 0.08). Total cholesterol (P = 0.02), MDA (P = 0.03), fat mass (P = 0.03) and visceral fat (P = 0.001) only showed decreased levels in LCG in comparison to the baseline condition. There was no significant difference between LCG and PLG, in the mean changes of hip circumference, visceral fat, free fat mass, fat mass, lipid profiles, CRP, MDA as well as stiffness, physical function, decrease of pain and total scores (P > 0.05). Conclusion The 12-week L-carnitine supplementation could improve BMI, but had no significant effect on other anthropometric and body composition measures as well as clinical symptoms, CRP, MDA, and lipid profile in women with KOA. Further trials with higher doses and longer durations are required. IRCT registration number: IRCT2017011932026N2. Registration date: 2017-04-27.

Backgrounds:L-carnitine decreases oxidation and inflammation by reducing the fatty acid in plasma and using oxygen in ATP synthesis. So, knee osteoarthritis (KOA) can be improved by reducing apoptotic chondrocytes. The aim of this study was to compare the effect of L-carnitine supplementation along with low calorie diet and low calorie diet alone on improvement of KOA among obese women. In other words, we aimed to investigate the additional effect of L- carnitine on improvement of KOA among obese women who received low calorie diet.Methods76 obese women with KOA were randomly assigned into two low-calorie diet groups; the first one received the 1000 mg L-carnitine (LCG) and with the second group took the placebo (PLG) (n = 38). Anthropometry indices, body composition, lipid profile, C- reactive Protein (CRP), Malondialdehyde (MDA), and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) WOMAC index were assessed at the baseline and after 12 weeks. Results: At the end of the study, the LCG showed significant improvements compared with the PLG in the total WOMAC scores (17.41 ± 9.81 compared with 23.50 ± 12.02 (P = 0.024)); physical function (11.15 ± 6. 56 compared with 15.61 ± 8.17 (P = 0.014)); BMI (-1.21 ± 0.84 kg/m2 compared with − 0.79 ± 0.70 kg/m2 (P = 0.027)). However, MDA, total cholesterol, fat and visceral fat mass decreased only in LCG significantly, but not in the PLG. Other variables did not have any significant changes. Conclusion: Oral administration of 1000 mg L-carnitine in 12 weeks could improve WOMAC score and BMI, but not affect CRP, MDA, and lipid profile. Further trials with higher doses and longer durations, are required to verify our results. IRCT registration number: IRCT2017011932026N2. Registration date: 2017-04-27.

Background Osteoarthritis is associated with obesity, dyslipidemia and cardiovascular diseases. It has been hypothesized that L-carnitine can improve cardiovascular risk factors. We aimed to investigate the effect of L-carnitine supplementation on lipid accumulation product (LAP) and atherogenic indices in women with overweight/obesity who have knee osteoarthritis. Methods In this double-blind randomized controlled trial, seventy-six women with overweight/obesity who had knee osteoarthritis were assigned into the intervention group and control group for 12 weeks. The intervention group received 1000 mg/day L-carnitine as capsule, and the control group received placebo. The primary outcomes were LAP, atherogenic index of plasma (AIP), atherogenic coefficient (AC) and Castelli risk index II (CRI-II). Results We found no significant difference between the groups in baseline values of LAP, AIP, AC and CRI-II. After the intervention, a significant reduction in LAP was observed in intervention group compared to the control group (− 11.05 (− 28.24 to 0.40) vs. − 5.82 (− 24.44 to 2.68); P = 0.03). However, there was no significant difference between two groups in AIP (− 0.05 ± 0.16 vs. − 0.01 ± 0.13; P = 0.19), AC (− 0.40 ± 0.81 vs. − 0.30 ± 0.67; P = 0.67) and CRI-II (− 0.20 ± 0.76 vs. − 0.21 ± 0.47; P = 0.11). Conclusions L-carnitine supplementation for 12 weeks can improve LAP, but it has no effect on cardiovascular outcomes. To reach a definitive conclusion, further clinical trials with larger sample sizes and higher dosages of L-carnitine are needed. Trial registration Registered on 27/4/2017 at Iranian Registry of Clinical Trials IRCT2017011932026N2.