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1.
The Effect of L-Carnitine on Mortality Rate in Septic Patients: A Systematic Review and Meta-Analysis on Randomized Clinical Trials.
Abdollahi, H, Abdolahi, M, Sedighiyan, M, Jafarieh, A
Endocrine, metabolic & immune disorders drug targets. 2021;(4):673-681
Abstract
BACKGROUND Recent clinical trial studies have reported that L-carnitine supplementation can reduce the mortality rate in patients with sepsis, but there are no definitive results in this context. The current systematic review and meta-analysis aimed to evaluate the effect of L-carnitine supplementation on 28-day and one-year mortality in septic patients. METHODS A systematic search conducted on Pubmed, Scopus and Cochrane Library databases up to June 2019 without any language restriction. The publications were reviewed based on the Cochrane handbook and preferred reporting items for systematic reviews and meta-analyses (PRISMA). To compare the effects of L-carnitine with placebo, Risk Ratio (RR) with 95% confidence intervals (CI) were pooled according to the random effects model. RESULTS Across five enrolled clinical trials, we found that L-carnitine supplementation reduce one-year mortality in septic patients with SOFA> 12 (RR: 0.68; 95% CI: 0.49 to 0.96; P= 0.03) but had no significant effect on reducing 28-day mortality ((RR: 0.93; 95% CI: 0.68 to 1.28; P= 0.65) compared to placebo. Finally, we observed that based on current trials, L-carnitine supplementation may not have clinically a significant effect on mortality rate. CONCLUSION L-carnitine patients with higher SOFA score can reduce the mortality rate. However, the number of trials, study duration and using a dosage of L-carnitine are limited in this context and further large prospective trials are required to clarify the effect of L-carnitine on mortality rate in septic patients.
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2.
Effect of L-carnitine supplementation on renal anemia in patients on hemodialysis: a meta-analysis.
Zhu, Y, Xue, C, Ou, J, Xie, Z, Deng, J
International urology and nephrology. 2021;(10):2149-2158
Abstract
BACKGROUND L-carnitine is an amino acid derivative that is thought to be helpful for treating renal anemia in hemodialysis patients. However, the mechanism remains to be fully elucidated. METHODS A literature search was performed on PubMed, Embase, and Cochrane Central Register of Controlled Trials to identify randomized controlled trials (RCTs) and conduct a meta-analysis for investigating the effect of L-carnitine in the treatment of renal anemia in participants receiving hemodialysis. RESULTS A total of 18 eligible trials with 1090 participants were included in this study. L-carnitine can significantly increase plasma free L-carnitine levels (mean difference [MD]: 140.53, 95% confidence interval [CI] 102.22-178.85; P < 0.00001), decrease the erythropoietin responsiveness index (ERI; MD: -2.72, 95% CI -3.20 to -2.24; P < 0.00001) and the required erythropoiesis-stimulating agent (ESA) doses (MD: -1.70, 95% CI -2.04 to -1.36; P < 0.00001). However, the use of L-carnitine was not associated with a higher hemoglobin level (MD: 0.18, 95% CI -0.20 to 0.55; P = 0.35) and hematocrit level (MD: 1.07, 95% CI -0.73 to 2.87; P = 0.24). In subgroup analyses, the effects of L-carnitine supplementation on renal anemia in patients on hemodialysis were independent of the treatment duration and intervention routes. CONCLUSION The present meta-analysis indicated that L-carnitine therapy significantly increased plasma L-carnitine concentrations, improved the response to ESA, decreased the required ESA doses in patients receiving hemodialysis, and maintained hemoglobin and hematocrit levels. L-carnitine supplementation should be supported in hemodialysis patients. However, the relationship between L-carnitine treatment and long-term outcomes is still unclear. Further high-quality RCTs are needed to verify our findings.
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3.
Beneficial effects of l-carnitine supplementation for weight management in overweight and obese adults: An updated systematic review and dose-response meta-analysis of randomized controlled trials.
Askarpour, M, Hadi, A, Miraghajani, M, Symonds, ME, Sheikhi, A, Ghaedi, E
Pharmacological research. 2020;:104554
Abstract
Despite preclinical studies demonstrating the efficacy of l-carnitine supplementation for weight management, findings in clinical setting are contradictory. Electronic bibliographical databases were systematically searched up to February 2019 with no limitation in language, including Scopus, PubMed, ISI Web of Science and Cochrane Library. Clinical trials registry platform were also searched. All randomized controlled trials (RCTs) which reported an effect of l-carnitine supplementation on obesity-related indices were included. Weighted mean difference (WMD) was estimated using a random-effect model (DerSimonian-Laird method). Eventually 43 eligible RCTs were included for quantitative analysis. Meta-analysis results revealed that l-carnitine supplementation significantly decreased weight (WMD: -1.129 kg, 95 % CI: -1.590, -0.669; I2: 63.4), body mass index (BMI) (WMD: -0.359 kg/m2, 95 % CI: -0.552, -0.167; I2: 85.2) and fat mass (WMD: -1.158 kg, 95 % CI: -1.763, -0.554, I2: 15.5). However, l-carnitine supplementation did not change body fat percentage (WMD: -0.874 %, 95 % CI: -1.890, 0.142, I2: 98.2) or waist circumference (WMD: -0.883 mg/dl, 95 % CI: -1.770, 0.004, I2: 74.8). l-Carnitine supplementation changed weight (r = -0.98) and BMI (r = -0.67) in a non-linear fashion based on carnitine dosage and BMI according to trial duration (r = -0.04). Interestingly subgroup analysis revealed that l-carnitine showed anti-obesity effects only in overweight and obese subjects; l-carnitine decreased weight, and BMI alone when combined with other lifestyle modifications. Anthropometric indexes were not changed following l-carnitine supplementation among patients' undergoing hemodialysis. Our study revealed that l-carnitine supplementation might have a positive effects in achieving an improved body weight and BMI especially in overweight and obese subjects.
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4.
The effect of l-carnitine supplementation on lipid profile and glycaemic control in adults with cardiovascular risk factors: A systematic review and meta-analysis of randomized controlled clinical trials.
Asadi, M, Rahimlou, M, Shishehbor, F, Mansoori, A
Clinical nutrition (Edinburgh, Scotland). 2020;(1):110-122
Abstract
BACKGROUND & AIMS Several randomized clinical trials (RCTs) have investigated the effect of l-carnitine supplementation on lipid profile and glycaemic control in adults with cardiovascular risk factors; however, the results were conflicting. Therefore, a meta-analysis was performed to assess the effect of l-carnitine on lipid profile and glycaemic control in adults with cardiovascular risk factors. METHODS We searched PubMed, Scopus, Cochrane Databases, Google Scholar, ProQuest, Web of Science and Embase for randomized, placebo-controlled human trials that investigated the effect of l-carnitine supplementation on lipid profile and glycaemic control up to April 2017. From the eligible trials, 24 articles were selected for the meta-analysis. The meta-analysis was performed in a random-effects model. Heterogeneity was determined by I2 statistics and Cochrane Q test. RESULTS The result showed significant effect of l-carnitine on TC (WMD: -13.73 [95% CI: -22.28, -5.17] mg/dL; P < 0.001), LDL-C (WMD = - 7.70 [95% CI: - 11.80, -3.61]mg/dL; p < 0.001), HDL-C (WMD = 0.82 [95% CI: 0.44, 1.21] mg/dL; P > 0.001), Lp(a) (WMD = - 7.13 [95% CI: -9.82,- 4.43]mg/dL; P < 0.001), FPG (WMD = -6.25 [95% CI: -10.35, -2.16] mg/dL; P < 0.001), HbA1C (WMD (%) = - 0.35 [95% CI: -0.65,- 0.05]; p = 0.02) and HOMA-IR (WMD (%) = - 0.94 [95% CI: -1.89, -0.00]; P = 0.05). No effect of l-carnitine was detected in TG, Apo A-I and Apo B 100 on pooled effect size. Additionally, sensitivity analysis showed l-carnitine supplementation could improve glycaemic control, particularly along with hypocaloric diet. CONCLUSION This meta-analysis showed that l-carnitine supplementation could improve lipid profile levels, particularly in doses more than 1500 mg/day. More RCTs with large sample sizes, focusing on gut microbiome profiles and dietary patterns are needed to better understand the effect of l-carnitine on patients with cardiovascular risk factors.
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5.
The Effect of L-Carnitine Supplementation on Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Randomized Clinical Trials.
Yarizadh, H, Shab-Bidar, S, Zamani, B, Vanani, AN, Baharlooi, H, Djafarian, K
Journal of the American College of Nutrition. 2020;(5):457-468
Abstract
Accumulating evidence of previous experimental studies indicated that L-Carnitine positively ameliorates muscle damage. However, findings from trials vary substantially across studies. Therefore, current meta-analysis aimed to examine the effects of L-Carnitine supplementation on exercise-induced muscle damage. An electronic search of the online literature databases (Medline (PubMed), Scopus and Google Scholar) was performed up to November 2018. Either a fixed-effects model or a random-effects model (Diasorin-Liard) was used in order to estimate the effects size. Cochran's Q test and I2 tests were used to assess the heterogeneity among the studies. Funnel plot and Egger's regression test were also employed in order to assess the publication bias. Of 604 studies, seven eligible randomized controlled trials (RCTs) were included in this meta-analysis. Pooled data from seven studies showed that L-Carnitine resulted in significant improvements in muscle soreness (MS) at the five follow-up time points (0, 24, 48, 72 and 96 hours (h)) compared to placebo. Also, pooled data indicated that L-Carnitine significantly reduced creatine kinase (CK), myoglobin (Mb), and lactate dehydrogenase (LDH) levels at one follow-up period (24 h). However, no effects have been observed beyond this period. Our outcomes indicate that L-Carnitine supplementation improves delayed-onset muscle soreness (DOMS) and markers of muscle damage. Further research is needed to clarify impacts of L-Carnitine on DOMS after different types of mechanical or chemical damages.Key teaching pointsThe effect of L-Carnitine supplementation on exercise-induced muscle damage has come under scrutiny over many years.This systematic review and meta-analyses study investigated the effects of L-Carnitine supplementation on exercise-induced muscle damage.Overall, summary results indicate that L-Carnitine supplementation improves muscle soreness and markers of muscle damage (CK, LDH, and Mb).Overall, L-carnitine supplementation ameliorated muscle damage only in resistance training groups and untrained population.
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6.
L-Carnitine's Effect on the Biomarkers of Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Choi, M, Park, S, Lee, M
Nutrients. 2020;(9)
Abstract
A systematic review and meta-analysis of randomized controlled trials (RCTs) was carried out to assess L-carnitine supplements' influence on the biomarkers of metabolic syndrome (MetSyn). PubMed, EMBASE, Cochrane library, and CINAHL were used to collect RCT studies published prior to February 2020. RCT studies were included if they had at least one of the following biomarker outcome measurements: waist circumference (WC), blood pressure (BP), fasting blood sugar (FBS), triglyceride (TG), or high density lipoprotein-cholesterol (HDLc). Nine of twenty studies with adequate methodological quality were included in this meta-analysis. The dose of L-carnitine supplementation administered varied between 0.75 and 3 g/day for durations of 8-24 weeks. L-carnitine supplementation significantly reduced WC and systolic BP (SBP), with no significant effects on FBS, TG, and HDLc. We found that L-carnitine supplementation at a dose of more than 1 g/d significantly reduced FBS and TG and increased HDLc. In conclusion, L-carnitine supplementation is correlated with a significant reduction of WC and BP. A dose of 1-3 g/d could improve the biomarkers of MetSyn by reducing FBS and TG and increasing HDLc.
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7.
Effects of carnitine supplementation on liver aminotransferase enzymes: A systematic review and meta-analysis of randomized controlled clinical trials.
Yousefi Rad, E, Eslampour, E, Falahi, E, Mardani, M, Hekmatdoost, A, Asbaghi, O, Saboori, S
Indian journal of gastroenterology : official journal of the Indian Society of Gastroenterology. 2019;(6):470-479
Abstract
BACKGROUND AND AIMS This meta-analysis of the randomized controlled trials was performed to assess effects of carnitine supplementation on serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. METHODS A comprehensive literature search of PubMed, Cochrane's library, Web of Science, Scopus, and Embase was performed up to May 2018. From a total of 2012 articles identified initially, only 17 articles were included in the final meta-analysis to evaluate the effects of carnitine supplementation on serum levels of ALT and AST enzymes. RESULTS Random effects model meta-analysis showed that carnitine supplementation led to reduction in serum ALT (weighted mean difference [WMD] - 10.25 IU/L; 95% CI = - 15.73, - 4.77; p < 0.001) and AST levels (WMD - 7.85 IU/L; 95% CI = - 11.85, - 3.86; p < 0.001). The results of subgroup analysis showed that carnitine could reduce serum AST levels at dosages equal to 2000 mg/day (p = 0.014) or more than 2000 mg/day (p < 0.001). However, carnitine supplementation at dosages of ≤ 1000 mg/day (p = 0.035) or equal to 2000 mg/day (p = 0.013) resulted in significant reduction in ALT level, while doses more than 2000 mg/day did not change ALT significantly. Carnitine exerts its reducing effect on serum ALT and AST levels only when these aminotransferases are raised or when the duration of supplementation lasts at least 3 months. CONCLUSION Results of the current meta-analysis showed that carnitine supplementation can decrease serum AST and ALT levels significantly, especially when supplementation lasts 3 months or more in patients with elevated serum aminotransferase levels.
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8.
Effect of L-carnitine on liver enzymes and biochemical factors in hepatic encephalopathy: A systematic review and meta-analysis.
Abbasnezhad, A, Choghakhori, R, Kashkooli, S, Alipour, M, Asbaghi, O, Mohammadi, R
Journal of gastroenterology and hepatology. 2019;(12):2062-2070
Abstract
BACKGROUND AND AIMS We aimed to investigate the effect of L-carnitine on biochemical factors including ammonia, bilirubin, albumin, alanine aminotransferase, aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine (Cr) in patients with hepatic encephalopathy (HE). METHODS A systematic search was carried out in Web of Science, PubMed, Scopus, and Cochrane Library databases to find articles related to the effect of L-carnitine supplementation in patients with HE, up to 7 February 2019. There was no language and time limitation. Meta-analyses were carried out using both the random and fixed effects models where appropriate, and I2 index was used to evaluate the heterogeneity. RESULTS Search yielded 3462 publications. Nine randomized clinical trials with 779 patients were eligible. L-carnitine supplementation significantly reduced blood levels of ammonia. Furthermore, our results indicated that L-carnitine supplementation significantly reduced blood levels of bilirubin, AST, BUN, and Cr in patients with HE. Subgroup analysis demonstrated that L-carnitine significantly reduced ammonia in patients with all the ages, long and short duration of the supplementation, doses less or higher than 4000 mg/day, any route of treatment (intravenous or oral), and in patients with any grade of the symptoms of HE. Moreover, we found that L-carnitine significantly increased circulating levels of albumin in HE patients. CONCLUSIONS Present systematic review and meta-analysis revealed that L-carnitine supplementation significantly reduced blood levels of ammonia, bilirubin, AST, BUN, and Cr in HE patients. Moreover, we found that L-carnitine significantly increased circulating levels of albumin. However, further large-scale randomized clinical trials are needed.
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9.
The effects of supplementation with L-carnitine on apolipoproteins: A systematic review and meta-analysis of randomized trials.
Sheikhi, A, Djafarian, K, Askarpour, M, Shab-Bidar, S
European journal of pharmacology. 2019;:172493
Abstract
Randomized controlled trials (RCTs) have reported that L-carnitin may change serum apolipoproteins. However, the results of RCTs are contradictory. Our objective was to conduct a systematic review and meta-analysis to summarize earlier RCTs on the effects of L-carnitine supplementation on apolipoproteins B100 and AI. ISI web of science, Ovid, PubMed/Medline, Scopus, and Google Scholar were searched from inception to January 2019 using relevant keywords. Treatment effects were considered as weighted mean difference (MD) and the corresponding 95% confidence interval in concentrations of serum apolipoproteins. Random-effects model (Dersimonian-Liard) was used to estimate the overall summary effect. This meta-analysis was performed on fourteen trials. Our results indicated that L-carnitine supplementation has a non-significant effect on Apo B100 (mean difference (MD): 1.820 mg/dl; 95% CI: -3.367 to 7.006, p = 0.492) and Apo AI (MD: -0.119 mg/dl; 95% CI: -4.425 to 4.186, p = 0.957). We also found body mass index, L-carnitine dosage; health condition and intervention duration could change the results. We conclude that L-carnitine does not change Apo B100 and Apo AI concentration. Further trials with sufficient sample size are needed to confirm these findings.
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10.
The Effects of L-Carnitine Supplementation on Serum Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Fathizadeh, H, Milajerdi, A, Reiner, Ž, Kolahdooz, F, Chamani, M, Amirani, E, Asemi, Z
Current pharmaceutical design. 2019;(30):3266-3281
Abstract
BACKGROUND The findings of trials investigating the effects of L-carnitine administration on serum lipids are inconsistent. This meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effects of L-carnitine intake on serum lipids in patients and healthy individuals. METHODS Two authors independently searched electronic databases including MEDLINE, EMBASE, Cochrane Library, Web of Science, PubMed and Google Scholar from 1990 until August 1, 2019, in order to find relevant RCTs. The quality of selected RCTs was evaluated using the Cochrane Collaboration risk of bias tool. Cochrane's Q test and I-square (I2) statistic were used to determine the heterogeneity across included trials. Weight mean difference (SMD) and 95% CI between the two intervention groups were used to determine pooled effect sizes. Subgroup analyses were performed to evaluate the source of heterogeneity based on suspected variables such as, participant's health conditions, age, dosage of L-carnitine, duration of study, sample size, and study location between primary RCTs. RESULTS Out of 3460 potential papers selected based on keywords search, 67 studies met the inclusion criteria and were eligible for the meta-analysis. The pooled results indicated that L-carnitine administration led to a significant decrease in triglycerides (WMD: -10.35; 95% CI: -16.43, -4.27), total cholesterol (WMD: -9.47; 95% CI: - 13.23, -5.70) and LDL-cholesterol (LDL-C) concentrations (WMD: -6.25; 95% CI: -9.30, -3.21), and a significant increase in HDL-cholesterol (HDL-C) levels (WMD: 1.39; 95% CI: 0.21, 2.57). L-carnitine supplementation did not influence VLDL-cholesterol concentrations. When we stratified studies for the predefined factors such as dosage, and age, no significant effects of the intervention on triglycerides, LDL-C, and HDL-C levels were found. CONCLUSION This meta-analysis demonstrated that L-carnitine administration significantly reduced triglycerides, total cholesterol and LDL-cholesterol levels, and significantly increased HDL-cholesterol levels in the pooled analyses, but did not affect VLDL-cholesterol levels; however, these findings were not confirmed in our subgroup analyses by participant's health conditions, age, dosage of L-carnitine, duration of study, sample size, and study location.