Effects of l-carnitine Supplement on Serum Amyloid A and Vascular Inflammation Markers in Hemodialysis Patients: A Randomized Controlled Trial

From genes to systems: The role of food supplementation in the regulation of sepsis-induced inflammation

Systemic inflammation includes a widespread immune response to a harmful stimulus that results in extensive systemic damage. One common example of systemic inflammation is sepsis, which is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Under the pro-inflammatory environment of sepsis, oxidative stress contributes to tissue damage due to dysfunctional microcirculation that progressively causes the failure of multiple organs that ultimately triggers death. To address the underlying inflammatory condition in critically ill patients, progress has been made to assess the beneficial effects of dietary supplements, which include polyphenols, amino acids, fatty acids, vitamins, and minerals that are recognized for their immuno-modulating, anticoagulating, and analgesic properties. Therefore, we aimed to review and discuss the contribution of food-derived supplementation in the regulation of inflammation from gene expression to physiological responses and summarize the precedented potential of current therapeutic approaches during systemic inflammation.

Carnitine supplements for people with chronic kidney disease requiring dialysis

BACKGROUND

Carnitine deficiency is common in patients with chronic kidney disease (CKD) who require dialysis. Several clinical studies have suggested that carnitine supplementation is beneficial for dialysis-related symptoms. However, the clinical effectiveness and potential adverse effects of carnitine supplementation in dialysis patients have not been determined.

OBJECTIVES

This review aimed to evaluate the effectiveness and safety of carnitine supplementation for the treatment of dialysis-related complications in CKD patients requiring dialysis.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 16 August 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) and quasi-RCTs (RCTs in which allocation to treatment was obtained by alternation, use of alternate medical records, date of birth, or other predictable methods) that compared carnitine supplements with placebo or standard care in people with CKD requiring dialysis.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted study data and assessed study quality. We used a random-effects model to perform a quantitative synthesis of the data.  We used the I² statistic to measure heterogeneity amongst the studies in each analysis. We indicated summary estimates as a risk ratio (RR) for dichotomous outcomes, mean difference (MD) for continuous outcomes, or standardised mean differences (SMD) if different scales were used, with 95% confidence intervals (CI). We assessed the certainty of the evidence for each of the main outcomes using the GRADE (Grades of Recommendation, Assessment, Development, and Evaluation) approach.

MAIN RESULTS

We included 52 studies (47 parallel RCTs and five cross-over RCTs) (3398 randomised participants). All studies compared L-carnitine with a placebo, other treatment, or no treatment. Standard care was continued as co-interventions in each group. Most studies were judged to have an unclear or high risk of bias. L-carnitine may have little or no effect on the quality of life (QoL) SF-36 physical component score (PCS) (4 studies, 134 participants: SMD 0.57, 95% CI -0.15 to 1.28; I² = 73%; low certainty of evidence), and the total QoL score (Kidney Disease Quality of Life (KDQOL), VAS (general well-being), or PedsQL) (3 studies, 230 participants: SMD -0.02, 95% CI -0.29 to 0.25; I² = 0%; low certainty of evidence). L-carnitine may improve SF-36 mental component score (MCS) (4 studies, 134 participants: SMD 0.70, 95% CI 0.22 to 1.18; I² = 42%; low certainty of evidence). L-carnitine may have little or no effect on fatigue score (2 studies, 353 participants: SMD 0.01, 95% CI -0.20 to 0.23; I² = 0%; low certainty of evidence), adverse events (12 studies, 1041 participants: RR, 1.14, 95% CI 0.86 to 1.51; I² = 0%; low certainty of evidence), muscle cramps (2 studies, 102 participants: RR, 0.44, 95% CI 0.18 to 1.09; I² = 23%; low certainty of evidence), and intradialytic hypotension (3 studies, 128 participants: RR, 0.76, 95% CI 0.34 to 1.69; I² = 0%; low certainty of evidence). L-carnitine may improve haemoglobin levels (26 studies, 1795 participants: MD 0.46 g/dL, 95% CI 0.18 to 0.74; I² = 86%; low certainty of evidence) and haematocrit values (14 studies, 950 participants: MD 1.78%, 95% CI 0.38 to 3.18; I² = 84%; low certainty of evidence).

AUTHORS' CONCLUSIONS

The available evidence does not currently support the use of carnitine supplementation in the treatment of dialysis-related carnitine deficiency. Although carnitine supplementation may slightly improve anaemia-related markers, carnitine supplementation makes little or no difference to adverse events. However, these conclusions are based on limited data and, therefore, should be interpreted with caution.

Significance of Levocarnitine Treatment in Dialysis Patients

Carnitine is a naturally occurring amino acid derivative that is involved in the transport of long-chain fatty acids to the mitochondrial matrix. There, these substrates undergo β-oxidation, producing energy. The major sources of carnitine are dietary intake, although carnitine is also endogenously synthesized in the liver and kidney. However, in patients on dialysis, serum carnitine levels progressively fall due to restricted dietary intake and deprivation of endogenous synthesis in the kidney. Furthermore, serum-free carnitine is removed by hemodialysis treatment because the molecular weight of carnitine is small (161 Da) and its protein binding rates are very low. Therefore, the dialysis procedure is a major cause of carnitine deficiency in patients undergoing hemodialysis. This deficiency may contribute to several clinical disorders in such patients. Symptoms of dialysis-related carnitine deficiency include erythropoiesis-stimulating agent-resistant anemia, myopathy, muscle weakness, and intradialytic muscle cramps and hypotension. However, levocarnitine administration might replenish the free carnitine and help to increase carnitine levels in muscle. This article reviews the previous research into levocarnitine therapy in patients on maintenance dialysis for the treatment of renal anemia, cardiac dysfunction, dyslipidemia, and muscle and dialytic symptoms, and it examines the efficacy of the therapeutic approach and related issues.

Effects of soy isoflavones on serum systemic and vascular inflammation markers and oxidative stress in peritoneal dialysis patients: A randomized controlled trial

Cardiovascular disease (CVD) is common in peritoneal dialysis (PD) patients. This study was designed to investigate the effects of isoflavones on systemic and vascular inflammation markers and oxidative stress in PD patients. In this randomized clinical trial, 40 PD patients were randomly assigned to either the isoflavone or the placebo group. The isoflavone group received 100 mg soy isoflavones daily for 8 weeks, whereas the placebo group received corresponding placebos. At baseline and the end of eighth week, serum high sensitive C-reactive protein (hs-CRP), intercellular adhesion molecule type 1 (ICAM-1), vascular cell adhesion molecule type 1 (VCAM-1), E-selectin, and malondialdehyde were measured. Serum VCAM-1 decreased significantly in the isoflavone group at the end of Week 8 compared to baseline (p = .01), whereas no significant change was observed in the placebo group. Serum ICAM-1 decreased significantly in the isoflavone (p = .01) and placebo (p = .01) group compared to baseline. However, the reduction of ICAM-1 was significantly higher in the isoflavone group than in the placebo group (p = .02). There were no significant differences between the two groups in mean changes of serum E-selectin, malondialdehyde, and hs-CRP. This study indicates that isoflavones reduce serum VCAM-1 and ICAM-1, which are two CVD risk factors, in PD patients.

Kinetics of carnitine concentration after switching from oral administration to intravenous injection in hemodialysis patients

Carnitine has high dialyzability and is often deficient in dialysis patients. This deficiency is treated by either intravenous (IV) or oral supplementation of carnitine. In this study, the mode of carnitine administration was changed from oral to IV in 17 hemodialysis (HD) patients, and the treatment was discontinued after 1 year. We found that the levels of total carnitine (TC), free-carnitine (FC), and acyl-carnitine (AC) significantly increased after 3 months of switching to IV administration (p < .05). After discontinuation of carnitine administration, the TC, FC, and AC levels decreased before dialysis. The average FC value was maintained at the normal levels until 9 months, but fell below the normal values when measured at the 12th month of discontinuation. In conclusion, carnitine was maintained at significantly high levels despite the smaller dose by IV infusion as compared with that by oral administration. We therefore suggest that our results be considered while determining both the carnitine administration route and the administration period in dialysis patients under clinical settings.

Effects of L-carnitine supplementation on lipid profiles in patients with coronary artery disease

Background

L-carnitine (LC) plays an important physiologic role in lipid metabolism. To date, no clinical study has been performed to examine the effect of LC supplementation on the lipid status of coronary artery disease (CAD) patients. The aim of this study was to investigate the lipid lowering effects of LC supplementation (1000 mg/d) in CAD patients.

Methods

CAD patients were identified by cardiac catheterization as having at least 50 % stenosis of one major coronary artery. Forty-seven subjects were recruited and randomly assigned to the placebo (n = 24) and to the LC (n = 23) groups. The intervention was administered for 12 weeks. The levels of LC, lipid profiles, and antioxidant enzyme activity (superoxide dismutase, SOD) were measured.

Results

The subjects in the LC group had significantly higher SOD activity (20.7 ± 4.2 versus 13.1 ± 2.9 U/mg of protein, P < 0.01), high density lipoprotein-cholesterol (1.34 ± 0.42 vs. 1.16 ± 0.24 mmol/L, HDL-C, P = 0.03), and apolipoprotein-A1 (Apo-A1, 1.24 ± 0.18 vs. 1.12 ± 0.13 g/L, P = 0.02) than those in the placebo group at week 12. Triglyceride (TG) level was slightly significantly reduced (1.40 ± 0.74 vs. 1.35 ± 0.62 mmol/L, P = 0.06) and the level of LC was negatively correlated with TG and apolipoprotein-B (Apo-B), and positively correlated with HDL-C and Apo-A1 after LC supplementation. Additionally, SOD activity was significantly negatively correlated with lipid profiles (total cholesterol, TG, and Apo-B) after supplementation.

Conclusion

LC supplementation at a dose of 1000 mg/d showed significantly increased in HDL-C and Apo-A1 levels and a slight decrease in TG levels but no other changes in other lipids in CAD patients, and this lipid-lowering effect may be related to its antioxidant ability. Further studies should be conducted to define an optimal dose of LC for lipid-lowering in patients with CAD.

Trial registration

Clinical Trials.gov Identifier: NCT01819701

Effects of levocarnitine on brachial-ankle pulse wave velocity in hemodialysis patients: a randomized controlled trial

Background and Aims: Atherosclerotic cardiovascular disease is the most common cause of mortality in patients with end-stage kidney disease. Chronic kidney disease patients often exhibit a deficiency in l-carnitine due to loss during hemodialysis (HD). We studied the effects of l-carnitine supplementation on brachial-ankle pulse wave velocity (baPWV), a marker of atherosclerosis, in HD patients. Methods: This was a prospective, open-label, randomized, parallel controlled, multi-center trial testing the anti-atherosclerotic efficacy of oral l-carnitine administration (20 mg/kg/day). HD patients (n = 176, mean age, 67.2 ± 10.3 years old; mean duration of HD, 54 ± 51 months) with plasma free l-carnitine deficiency (<40 μmol/L) were randomly assigned to the oral l-carnitine group (n = 88) or control group (n = 88) and monitored during 12 months of treatment. Results: There were no significant differences in baseline clinical variables between the l-carnitine and control groups. l-carnitine supplementation for 12 months significantly increased total, free, and acyl carnitine levels, and reduced the acyl/free carnitine ratio. The baPWV value decreased from 2085 ± 478 cm/s at baseline to 1972 ± 440 cm/s after six months (p < 0.05) to 1933 ± 363 cm/s after 12 months (p < 0.001) of l-carnitine administration, while no significant changes in baPWV were observed in the control group. Baseline baPWV was the only factor significantly correlated with the decrease in baPWV. Conclusions: l-carnitine supplementation significantly reduced baPWV in HD patients. l-carnitine may be a novel therapeutic strategy for preventing the progression of atherosclerotic cardiovascular disease.

Current experience in testing mitochondrial nutrients in disorders featuring oxidative stress and mitochondrial dysfunction: rational design of chemoprevention trials

An extensive number of pathologies are associated with mitochondrial dysfunction (MDF) and oxidative stress (OS). Thus, mitochondrial cofactors termed "mitochondrial nutrients" (MN), such as α-lipoic acid (ALA), Coenzyme Q10 (CoQ10), and l-carnitine (CARN) (or its derivatives) have been tested in a number of clinical trials, and this review is focused on the use of MN-based clinical trials. The papers reporting on MN-based clinical trials were retrieved in MedLine up to July 2014, and evaluated for the following endpoints: (a) treated diseases; (b) dosages, number of enrolled patients and duration of treatment; (c) trial success for each MN or MN combinations as reported by authors. The reports satisfying the above endpoints included total numbers of trials and frequencies of randomized, controlled studies, i.e., 81 trials testing ALA, 107 reports testing CoQ10, and 74 reports testing CARN, while only 7 reports were retrieved testing double MN associations, while no report was found testing a triple MN combination. A total of 28 reports tested MN associations with "classical" antioxidants, such as antioxidant nutrients or drugs. Combinations of MN showed better outcomes than individual MN, suggesting forthcoming clinical studies. The criteria in study design and monitoring MN-based clinical trials are discussed.

Antiinflammatory effects of L-carnitine supplementation (1000 mg/d) in coronary artery disease patients

OBJECTIVE

Inflammation mediators have been recognized as risk factors for the pathogenesis of coronary artery disease (CAD). The purpose of this study was to investigate the effect of L-carnitine supplementation (LC, 1000 mg/d) on inflammation markers in patients with CAD.

METHODS

We enrolled 47 patients with CAD in the study. The patients with CAD were identified by cardiac catheterization as having <50% stenosis of one major coronary artery. The patients were randomly assigned to the placebo (n = 24) and LC (n = 23) groups and the intervention was administered for 12 wk. The levels of LC, antioxidant status (malondialdehyde and antioxidant enzymes activities), and inflammation markers (C-reactive protein [CRP], interleukin [IL]-6, and tumor necrosis factor [TNF]-α) were measured.

RESULTS

Thirty-nine participants completed the study (19 placebo; 20 LC). After LC supplementation, the levels of inflammation markers were significantly reduced compared with the baseline (CRP, P < 0.01; IL-6, P = 0.03; TNF-α, P = 0.07) and those in the placebo group (CRP, P < 0.05; IL-6, P = 0.04; TNF-α, P = 0.03). The levels of inflammation markers were significantly negatively correlated with the levels of LC and antioxidant enzymes activities (P < 0.05).

CONCLUSIONS

We suggest that LC supplementation, due to its antioxidant effects, may have potential utility to reduce inflammation in CAD.

L-Carnitine supplementation for adults with end-stage kidney disease requiring maintenance hemodialysis: a systematic review and meta-analysis

BACKGROUND

A previous meta-analysis indicated that l-carnitine significantly increased hemoglobin and decreased the required erythropoietin dose in maintenance hemodialysis patients.

OBJECTIVE

An updated systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to reevaluate effects of l-carnitine.

DESIGN

The Cochrane Library, PubMed, and EMBASE databases (31 December 2012) were searched to identify RCTs that investigated effects of l-carnitine in adults with end-stage kidney disease that required maintenance hemodialysis.

RESULTS

Forty-nine RCTs (1734 participants) were included. l-Carnitine significantly decreased serum low-density lipoprotein (LDL) (mean difference: -5.82 mg/dL; 95% CI: -11.61, -0.04 mg/dL) and C-reactive protein (CRP) (-3.65 mg/L; -6.19, -1.12 mg/L). There were no significant differences in triglycerides (-0.89 mg/dL; -29.32, 27.53 mg/dL), cholesterol (0.14 mg/dL; -6.15, 6.42 mg/dL), high-density lipoprotein (1.13 mg/dL; -2.44, 4.70 mg/dL), hemoglobin (0.68 g/dL; 0.14, 1.50 g/dL), hematocrit (2.04%; -1.39, 5.48%), albumin (1.65 g/L; -0.22, 3.51 g/L), or the required erythropoietin dose (-0.76 KU/wk; -1.75, 0.23 KU/wk). No adverse effects were reported.

CONCLUSIONS

This meta-analysis failed to confirm the previous findings regarding the effects of l-carnitine on hemoglobin and the erythropoietin dose but showed that l-carnitine significantly decreased serum LDL and CRP. The extent of the decrease in LDL was not clinically relevant, whereas the significant decrease in CRP was both statistically and clinically relevant. However, the relevance of decrease in CRP with hard endpoints such as all-cause mortality and cardiovascular complications still remains to be clarified.

Effect of L-carnitine therapy on patients in maintenance hemodialysis: a systematic review and meta-analysis

BACKGROUND

L-Carnitine has been used as adjuvant therapy in hemodialysis (HD) patients for many years. However, there is controversy whether L-carnitine supplementation is beneficial. Therefore we performed a meta-analysis of randomized controlled trials (RCTs) to assess the effect of L-carnitine on HD patients.

METHODS

RCTs of L-carnitine versus placebo for HD patients were searched from Medline, EMBASE and the Cochrane Central Register of Controlled Trials. We screened relevant studies according to predefined inclusion and exclusion criteria, and performed meta-analyses using Revman 5.1 software.

RESULTS

Meta-analysis showed L-carnitine could not increase the total score of 36-item Short-Form Health Survey Questionnaire (SF-36) (SMD 0.76, 95 % CI -0.13 to 1.65, P = 0.09), and L-carnitine therapy did not improve serum C-reactive protein (SMD -0.37, 95 % CI -0.88 to 0.14, P = 0.16), oxidized low-density lipoprotein (SMD 0.04, 95 % CI -0.43 to 0.50, P = 0.87), albumin (SMD 0.25, 95 % CI -0.31 to 0.81, P = 0.38;), hemoglobin (SMD 0.23, 95 % CI -0.23 to 0.68, P = 0.33), cholesterol (SMD -0.24, 95 % CI -0.71 to 0.24, P = 0.33), triglycerides (SMD 0.02, 95 % CI -0.4 to 0.44, P = 0.91) or parathyroid hormone (SMD 0.21, 95 % CI -0.35 to 0.76, P = 0.46) levels.

CONCLUSIONS

There is no evidence that L-carnitine can improve the inflammation, oxidative stress, nutrition, anemia, dyslipidemia, hyperparathyroidism status or quality of life in HD patients. However, given methodological limitations and lack of hard endpoints, high-quality, long-term randomized trials are required to fully elucidate the clinical value of L-carnitine administration in hemodialysis patients.

L-carnitine supplementation in dialysis: treatment in quest of disease

L-Carnitine (LC) administration has been recommended for specific indications in dialysis patients, including epoetin-resistant anemia, intradialytic hypotension, cardiomyopathy, fatigue, muscle weakness, and exercise performance; it may ameliorate insulin resistance, inflammation, and protein wasting. Use of LC for anemia and intradialytic hypotension has been approved for reimbursement by the Centers for Medicare and Medicaid Services. Yet, the data to support these recommendations are inadequate and have not been bolstered over several decades. LC administration continues to appeal to nephrologists because its use in dialysis patients has an attractive rationale, it addresses problems that persist despite dialysis, it is safe, and the existing literature does not refute its use. Nevertheless, definitive trials to justify LC administration have not been conducted and are increasingly unlikely to be funded. In an era of shrinking resources and bundling of dialysis services, the use of LC in dialysis patients will, appropriately, diminish.

Prevalence of protein-energy wasting and its various types in Iranian hemodialysis patients: a new classification

BACKGROUND

This study was designed to determine the prevalence of protein-energy wasting (PEW) and its various types in hemodialysis (HD) patients in Tehran, Iran.

METHODS

For this cross-sectional study, 291 HD patients were randomly selected. The nutritional status of the patients was determined by subjective global assessment (SGA) and their dietary intakes were assessed using a 4-day dietary recall. In addition, serum high-sensitive C-reactive protein (hs-CRP) was measured.

RESULTS

The prevalence of mild-to-moderate and severe PEW based on SGA was 60.5% and 1% in Tehran HD patients, respectively. The prevalence of various types of PEW in HD patients was 20.5% type I (inadequate energy or protein intake without inflammation), 65.5% type IIa (inadequate energy or protein intake with inflammation), and 14% type IIb (adequate energy and protein intake with inflammation). Of the total HD patients with no PEW based on SGA, about 3.5% had type 0 normal nutritional status (adequate energy and protein intake without inflammation), 34% had type I normal nutritional status (inadequate energy or protein intake without inflammation), 55.5% had type IIa normal nutritional status (inadequate energy or protein intake with inflammation), and 7% had type IIb normal nutritional status (adequate energy and protein intake with inflammation).

CONCLUSION

PEW in Tehran HD patients is considerably prevalent and PEW type IIa is the most common type. In addition, HD patients with no PEW based on SGA should also be paid attention because they may be in the early stages of inadequate intake of energy and/or protein and inflammation.