Effect of chronic L-carnitine supplementation on carnitine levels, oxidative stress and apoptotic markers in peripheral organs of adult Wistar rats

The Effect of the L-Carnitine Supplementation on Obesity Indices: An Umbrella Meta-Analysis

AIMS

Obesity, one of the most frequent health risks, represents a global public health problem. The potential impact of L-carnitine, a vital nutrient for energy metabolism, on weight loss is worth considering. However, given the inconclusive results from recent meta-analyses on L-carnitine, we conducted an umbrella meta-analysis of placebo-controlled and controlled trials to evaluate the effect of L-carnitine on anthropometric indices.

METHODS

Data synthesis: A comprehensive search approach using the relevant keywords was performed in PubMed, Web of Science, Scopus databases, and Google Scholar up to March 2023. Meta-analyses published in English that provided quantitative statistical analyses regarding the effects of L-carnitine on body weight, waist circumference (WC), and body mass index (BMI) were included. A random-effects model and subgroup analysis were performed based on the L-carnitine dosage and study population.

RESULTS

A total of 16,352 participants were included. Intervention durations ranged from 8 to 30 weeks, with L-carnitine dosages ranging between 150 and 4000 mg/day. The pooled results of the eight included meta-analyses indicated that L-carnitine supplementation can significantly decrease weight (effect size (ES) = -1.11; 95% confidence intervals (CIs): -1.90, -0.33, p = 0.005; I2 = 90.6%, p < 0.001), BMI (ES = -0.33; 95% CI: -0.61, -0.04, p = 0.026; I2 = 89.8%, p < 0.001), and WC (ES = -1.34; 95% CI: -1.83, -0.85, p < 0.001; I2 = 00.0%, p = 0.442).

CONCLUSION

The findings of this umbrella meta-analysis support that supplementation of L-carnitine supplementation can successfully manage weight, BMI, and WC reduction. Therefore, L-carnitine might help treat obesity. PROSPERO Registration Number: CRD42022307951.

Electroacupuncture pretreatment at ST36 alleviates acute gastric mucosal lesions induced by water immersion restraint stress through the TRPV1/SP/CGRP/NO pathway in rats

OBJECTIVE

The aim of this study was to determine the impact of electro-acupuncture (EA) pretreatment on the progression of acute gastric mucosal lesions (AGMLs) induced by water immersion restraint stress (WIRS) and explore the related mechanisms including the transient receptor potential vanilloid (TRPV)1 signaling pathways.

METHODS

Rats treated with EA for 4 days were subjected to WIRS for 6 h. Microscopic lesions, oxidative stress and TRPV1, substance P (SP), calcitonin gene-related peptide (CGRP) and nitric oxide (NO) levels in the dorsal root ganglion (DRG) and gastric tissues were detected.

RESULTS

The results indicated the development of AGMLs with a substantial increase of TRPV1/SP in the DRG and TRPV1/SP/MDA (malondialdehyde activity) in the stomach, and a significant decrease in CGRP/NO/SOD (superoxide dismutase) in gastric tissues, using a combination of real-time reverse transcription polymerase chain reaction, Western blotting and enzyme-linked immunosorbent assay.

CONCLUSION

The TRPV1 signaling pathways likely play an important role in the pathogenesis of AGML. In addition, EA pretreatment protected gastric mucosa lesions induced by WIRS by reducing the expression of TRPV1/SP in the DRG and gastric mucosa, as well as up-regulating gastric CGRP/NO. Antioxidant mechanisms are likely to at least partially mediate the protective effects of EA against AGML.

L-Carnitine Improves Muscle Nutrient Metabolism and Intestinal Health in High-Fat-Fed Carp (Cyprinus carpio)

L-Carnitine is widely recognized for its involvement in lipid metabolism, but its effects on muscle quality and gut health in carp have not been well studied. The research aimed to investigate how L-carnitine influences muscle quality and intestinal health in high-fat-fed carp. The study was separated into four groups that received either the standard diet, a high-fat diet (HFD), or a HFD supplemented with 500 mg/kg L-carnitine (LLC), or a HFD supplemented with 1000 mg/kg L-carnitine (HLC) for 56 days. L-Carnitine was found to significantly reduce blood lipid levels. In addition, L-carnitine increased the crude protein content and decreased the crude fat content of high-fat-fed carp muscle while improving muscle fiber morphology and muscle quality. L-Carnitine increased the expression of genes related to intestinal tight junction proteins (claudin-2, occludin, and zo-1), improved the expression of genes related to intestinal inflammation, and enhanced the physical barrier function and organization of the intestine. Analysis of intestinal flora and intestinal metabolites showed that L-carnitine increased the diversity of the intestinal flora, increased the abundance of Cetobacterium, and influenced intestinal levels of bile acids, arachidonic acid, and tryptophan-related metabolites. In conclusion, supplementation with 1000 mg/kg L-carnitine improved muscle quality and intestinal health significantly in high-fat-fed carp by regulating muscle nutrient metabolism and intestinal flora.

Acetyl-L-carnitine attenuates chronic ethanol-induced oxidative stress, ER stress and apoptosis in rat gastric tissue

Consuming alcohol affects almost all organs. Acetaldehyde, formed as the main product as a result of alcohol metabolism, causes the production of free superoxide radicals when oxidized, and accordingly oxidative and apoptotic processes are triggered. There are studies showing that carnitine has effects on oxidative and apoptotic processes that occur in various conditions. However, the mechanisms showing the effects of L-carnitine on these effects of alcohol have not been fully elucidated. In our study, the effects of acetyl-L-carnitine administration on the molecular mechanisms of oxidative stress, endoplasmic reticulum stress, and apoptotic parameters in gastric tissue of rats chronically exposed to alcohol were investigated. Hematoxylin-eosin staining was used for histopathological studies. Endoplasmic reticulum stress markers were detected with immunohistochemical staining and western blotting. Apoptotic index was evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Total oxidant and antioxidant status were examined by ELISA. Our results showed that chronic alcohol administration caused a significant increase in TOS levels, an indicator of oxidative stress, the levels of ER-stress-associated proteins XBP1, GRP78, and CHOP, and % apoptotic index values in rat gastric tissues. Additionally, it was determined that acetyl-L-carnitine administration caused an improvement in those values. Based on our data, we can conclude that acetyl-L-carnitine has a tissue protective effect by scavenging free oxygen radicals and reducing ER stress-related proteins XBP1, GRP78, and CHOP and apoptosis in chronic ethanol-administered rats, and that this natural antioxidant may be beneficial in the treatment of oxidative stress-induced diseases.

Acyl-Carnitines Exert Positive Effects on Mitochondrial Activity under Oxidative Stress in Mouse Oocytes: A Potential Mechanism Underlying Carnitine Efficacy on PCOS

Carnitines play a key physiological role in oocyte metabolism and redox homeostasis. In clinical and animal studies, carnitine administration alleviated metabolic and reproductive dysfunction associated with polycystic ovarian syndrome (PCOS). Oxidative stress (OS) at systemic, intraovarian, and intrafollicular levels is one of the main factors involved in the pathogenesis of PCOS. We investigated the ability of different acyl-carnitines to act at the oocyte level by counteracting the effects of OS on carnitine shuttle system and mitochondrial activity in mouse oocytes. Germinal vesicle (GV) oocytes were exposed to hydrogen peroxide and propionyl-l-carnitine (PLC) alone or in association with l-carnitine (LC) and acetyl-l-carnitine (ALC) under different conditions. Expression of carnitine palmitoyltransferase-1 (Cpt1) was monitored by RT-PCR. In in vitro matured oocytes, metaphase II (MII) apparatus was assessed by immunofluorescence. Oocyte mitochondrial respiration was evaluated by Seahorse Cell Mito Stress Test. We found that Cpt1a and Cpt1c isoforms increased under prooxidant conditions. PLC alone significantly improved meiosis completion and oocyte quality with a synergistic effect when combined with LC + ALC. Acyl-carnitines prevented Cpt1c increased expression, modifications of oocyte respiration, and ATP production observed upon OS. Specific effects of PLC on spare respiratory capacity were observed. Therefore, carnitine supplementation modulated the intramitochondrial transfer of fatty acids with positive effects on mitochondrial activity under OS. This knowledge contributes to defining molecular mechanism underlying carnitine efficacy on PCOS.

The effects of curcumin and sertraline on stress-induced changes in the stomach tissues of rats

Exposure to stressors can cause functional disorders and structural damage to the stomach. Sertraline (SER) is an antidepressant and curcumin (CUR) is a natural compound with many properties. The current study aimed to investigate the impacts of stress, SER, and CUR on the stomach tissue using stereological methods. In total, 24 male and 24 female Sprague-Dawley rats were divided into four groups. In the control group, the rats were not exposed to stress. However, the animals in stress, SER and, CUR groups were exposed to daily stress and were orally fed with distilled water, SER (10 mg/kg/day), and CUR (100 mg/kg/day), respectively. The volume, surface area, and number of nerve, parietal, and chief cells were evaluated by stereological methods. Results showed that stress increased the stomach and its mucosa and submucosa volumes, while it decreased the surface area of the mucosa. Furthermore, this disorder increased the number of neurons in the submucosa and myenteric plexuses while it decreased the number of parietal and chief cells. However, treating stressed rats with SER or CUR could prevent these changes. The results showed that the consumption of SER or CUR could be used as a preventive or adjunctive treatment for stressful situations.

L-Carnitine alleviates hepatic and renal mitochondrial-dependent apoptotic progression induced by letrozole in female rats through modulation of Nrf-2, Cyt c and CASP-3 signaling

Letrozole (LTZ) is a non-steroidal aromatase inhibitor that is commonly used in breast cancer therapy. It has several side effects that might lead to the drug's cessation and data of LTZ's potential adverse effects on the hepatorenal microenvironment was conflicting. In addition, searching for therapeutic interventions that could modulate its adverse effects will be very beneficial. So, this study aims to determine the impact of LTZ on the hepatorenal microenvironment in cyclic female rats with a proposed regulatory role of L-Carnitine (LC) supplementation giving molecular insights into its possible mechanism of action. LTZ (1 mg/kg using 0.5% carboxy methyl cellulose as a vehicle for 21 consecutive days orally) to assess its impact on hepatorenal microenvironment. After treatment with LC (100 mg/kg orally) for 14 days, hepatorenal redox state (lipid peroxides (MDA), reduced glutathione (GSH) and catalase enzyme (CAT)), as well as relative gene expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), cytochrome-c (Cyt c) and caspase-3 (CASP-3) were evaluated. Histopathological examination and immunohistochemical staining of CASP-3 in both liver and kidney were done. LTZ altered hepatic and renal functions. Relative gene expression of hepatorenal Nrf-2, Cyt c and CASP-3 as well as redox state revealed significant deterioration. Also, the liver and kidney tissues showed several micromorphological changes and intense reaction to CASP-3 upon immunohistochemical staining. It can be concluded that LC alleviates LTZ induced hepatorenal oxidative stress (OS) and mitochondrial-dependent apoptotic progression through modulation of Nrf-2, Cyt c, and CASP-3 signaling in female rats.

A coffee enriched with guarana, selenium, and l-carnitine (GSC) has nutrigenomic effects on oxi-inflammatory markers of relapsing-remitting multiple sclerosis patients: A pilot study

Relapsing-remitting multiple sclerosis (RRMS) is the most common clinical course of multiple sclerosis (MS), characterized by a chronic inflammatory state and elevated levels of oxidative markers. Food supplements with potential anti-inflammatory, antioxidant and neuroprotective effects have been tested as possible adjuvants in the treatment of MS. In this sense, this pilot study was carried out with the aim of verifying whether a minimum daily dose of a guarana, selenium and l-carnitine (GSC) based multi supplement, mixed in cappuccino-type coffee, administered for 12 weeks to 28 patients with RRMS could differentially modulate oxidative blood markers (lipoperoxidation, protein carbonylation and DNA oxidation) and inflammatory blood markers (protein levels of cytokines IL-1β, IL-6, TNF-α, IFN-γ, IL-10, gene expression of these cytokines, and NLRP3 and CASP-1 molecules, and C-reactive protein levels). The results indicate that a low concentration of GSC is capable of decreasing the plasma levels of oxidized DNA and pro-inflammatory cytokines of RRMS patients. The results support further research into the action of GSC on clinical symptoms, not only in patients with MS, but also with other neurological conditions.

The protective effect of L-carnitine on testosterone synthesis pathway, and spermatogenesis in monosodium glutamate-induced rats

Background

Monosodium glutamate (MSG) is a food ingredient that is increasingly used commercially. MSG leads to oxidative stress, consequently suppressing steroid hormone production that causes defects in male reproductive system. This study aimed to evaluate the effect of L-carnitine as an antioxidant on testicular damage in MSG-induced male rats.

Methods

Sixty adult male Spargue-Dawley rats were randomly divided into six groups of ten as follows: control (water), sham (normal saline), L-carnitine (200 mg/kg b.w), MSG (3 g/kg b.w), MSG + L-carnitine 100 (3 g/kg b.w of MSG and 100 mg/kg b.w of L-carnitine), and MSG + L-carnitine 200 (3 g/kg b.w of MSG and 200 mg/kg b.w of L-carnitine). The treatment was administered by oral gavage for six months. Serum levels of Malondialdehyde (MDA), Total Anti-oxidant Capacity (TAC), LH, FSH, testosterone, and mRNA expressions of Star, Cyp11a1, and Hsd17b3 genes, and histological and stereological changes were assessed.

Results

L-carnitine led to a significant decrease in the level of MDA and a significant rise in the serum levels of TAC, LH, FSH, and mRNA expression of Star and Cyp11a1 compared to the MSG group (p < 0.05). Furthermore, stereological results indicated a significant increment in the number of sexual lineage cells, the total volume of the testis, length, diameter, and volume of seminiferous tubules, the height of the germinal epithelium, sperm count, and sperm motility (p < 0.05) in MSG + L-carnitine 200 compare to MSG group.

Conclusion

The study’s findings demonstrated that L-carnitine due to its anti-oxidant properties, ameliorated the reproductive abnormalities in the male rats exposed to MSG.

Combination therapy of Ulinastatin with Thrombomodulin alleviates endotoxin (LPS) - induced liver and kidney injury via inhibiting apoptosis, oxidative stress and HMGB1/TLR4/NF-κB pathway

Sepsis is a type of systemic inflammation response syndrome that leads to organ function disorders. Currently, there is no specific medicine for sepsis in clinical practice. Lipopolysaccharide (LPS) is an important endotoxin that causes sepsis. Here, we report an effective two-drug combination therapy to treat LPS-induced liver and kidney injury in endotoxic rats. Ulinastatin (UTI) and Thrombomodulin (TM) are biological macromolecules extracted from urine. In our study, combination therapy significantly improved LPS-induced liver and kidney pathological structure and functional injury, and significantly improved the survival rate of endotoxic rats. Results of TUNEL staining and Western blot showed that UTI combined with TM inhibited the excessive apoptosis of liver and kidney cells caused by LPS. The drug combination also promoted the proliferation of liver and kidney cells, reduced the levels of pro-inflammatory factors interleukin (IL)-6, IL-1β, tumor or necrosis factor (TNF)-α and nitric oxide, and down-regulated the expression of High Mobility Group Box 1 (HMGB1), Toll-like receptor (TLR) 4 and Nuclear Factor (NF)-κB phosphorylation to inhibit inflammation. In addition, the combination of UTI and TM also promoted the production of a variety of antioxidant enzymes in the tissues and inhibited the production of lipid peroxidation malondialdehyde (MDA) to enhance antioxidant defenses. Our experiments also proved that UTI combined with TM did not reduce the anticoagulant effect of TM. These results suggested that UTI combined with TM can improve endotoxin-induced liver and kidney damage and mortality by inhibiting liver and kidney cell apoptosis, promoting proliferation, and inhibiting inflammation and oxidative injury.

Diclofenac down-regulates COX-2 induced expression of CD44 and ICAM-1 in human HT29 colorectal cancer cells

Cyclooxygenase-2 (COX-2) is expressed in a variety of human colorectal cancer cells and can contribute to carcinogenesis. This study aimed to investigate the effect of diclofenac (DCF), a selective COX-2 inhibitor, on cell adhesion molecules and apoptosis in human colon adenocarcinoma cells. Levels of homing cell adhesion molecule (H-CAM, CD44), intercellular adhesion molecule-1 (ICAM-1, CD54), vascular cell adhesion molecule-1 (VCAM-1, CD106), and epithelial cell adhesion molecule (EpCAM, CD326) were evaluated in cancer cells overexpressing (HT29) or not expressing (HCT116) COX-2. Cell viability was determined by MTT assay, COX-2 protein levels and activity were assessed by immunofluorescence and fluorometric analysis, respectively. Endogenous levels of polyunsaturated fatty acids (PUFAs) were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) while expression of cell adhesion molecules was analyzed by flow cytometry. Annexin V-FITC/propidium iodide-labelling and fluorometric caspase-3 activity measurements were carried out to determine apoptosis. Flow cytometry analysis revealed that the percentage of CD44 and ICAM-1 staining in HCT116 cells was significantly lower compared to HT29 cells. In HT29 cells, phorbol 12-myristate 13-acetate (PMA) induced COX-2 expression and increased CD44 and ICAM-1 levels were down-regulated by diclofenac. Stimulation of COX-2 activity in HT29 cells via PMA significantly decreased diclofenac associated increase in PUFA levels. Treatment with both diclofenac and PMA significantly increased the number of apoptotic cells and caspase-3 activity in colon adenocarcinoma cells compared to control groups. In conclusion, diclofenac's effect to retard colorectal tumor growth and metastasis occurs in COX-2 overexpressing colon cancer cells by increased apoptosis and decreased expression of CD44 and ICAM-1.

Effect of l-carnitine supplementation on children and adolescents with nonalcoholic fatty liver disease (NAFLD): a randomized, triple-blind, placebo-controlled clinical trial

OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in the pediatric population at global level. Present study aims to assess the effect of l-carnitine supplementation on the NAFLD in children and adolescents.

METHODS

This randomized, triple-blind, placebo-controlled clinical trial was conducted in 2018-2019. Study was carried out in NAFLD participants (5-15 years). They were randomly assigned to receive either 50 mg/kg/day l-carnitine twice a day or identical placebo per day for three months. Liver enzymes and liver ultrasonography were assessed before and after the intervention. Both groups received similar consultation for lifestyle changes.

RESULTS

Overall, 55 participants completed the study, 30 patients in the l-carnitine group and 25 patients in placebo group. Mean changes of anthropometric measurements did not have significant differences between groups (p>0.05). No significant differences in the mean changes of aspartate aminotransferase (AST) (p=0.82) and alanine aminotransferase (ALT) (p=0.76) levels were documented between two groups. Based on within-group analysis, there were significant changes in AST and ALT levels before and after the intervention in both groups. The sonographic grades of fatty liver were not significantly different between two groups before (p=0.94) and after intervention (p=0.93).

CONCLUSIONS

In the present clinical trial, L-carnitine did not have significant effect on improving biochemical and sonographic markers of NAFLD in children and adolescents. Future studies are necessary to evaluate the applicability and efficacy of long-term l-carnitine supplementation to treatment of NAFLD in pediatric population.

TRIAL REGISTRATION

IRCT20170628034786N2.

Dietary supplementary glutamine and L-carnitine enhanced the anti-cold stress of Arbor Acres broilers

Newborn poultry in cold regions often suffer from cold stress, causing a series of changes in their physiology and metabolism, leading to slow growth and decreased production performance. However, a single anti-stress substance cannot completely or maximally eliminate or alleviate the various effects of cold stress on animals. Therefore, the effects of the supplemented glutamine and L-carnitine on broilers under low temperature were evaluated in this study. Broilers were randomly allocated into 16 groups which were respectively fed with different levels of glutamine and L-carnitine according to the L16 (45) orthogonal experimental design for 3 weeks (the first week is the adaptive feeding period; the second and third weeks are the cold exposure period). Growth performance was recorded, and blood samples were collected during cold exposure. The results showed the supplementation had altered the plasma parameters, growth performance and cold-induced oxidative stress. The increase of corticosterone and suppression of thyroid hormone was ameliorated. Supplemented groups had lower daily feed intake and feed-to-gain ratio, higher daily weight gain and better relative weights of immune organs. Plasma glucose, total protein, blood urea nitrogen and alkaline phosphatase changed as well. Oxidative stress was mollified due to the improved activities of superoxide dismutase and glutathione peroxidase, heightened total antioxidant capacity and stable malondialdehyde. Dietary glutamine and L-carnitine improve the growth performance, nutritional status and cold stress response of broilers at low temperature, and their interaction occurred.

L-carnitine extenuates endocrine disruption, inflammatory burst and oxidative stress in carbendazim-challenged male rats via upregulation of testicular StAR and FABP9, and downregulation of P38-MAPK pathways

We have addressed in the current study the potential of L-carnitine (LC) to extenuate the reproductive toxic insults of carbendazim (CBZ) in male rats, and the molecular mechanisms whereby carnitine would modify the spermatogenic and steroidogenic derangements invoked by the endocrine disruptor. Herein, animals received daily doses of carbendazim (100 mg/kg) by gavage for 8 weeks. Another CBZ-challenged group was co-supplemented with LC (500 mg/kg, IP) twice weekly for 8 weeks. Sperm quantity and quality (morphology, motility and viability), serum testosterone and gonadotropins, and thyroid hormone levels were assessed. Serum tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) concentrations were determined by ELISA. Oxidant/antioxidant status in rat testis was investigated via measuring testicular contents of malondialdehyde (MDA) and reduced glutathione (GSH), as well as the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Immunohistochemical localizations of the junctional protein; occludin, and inflammatory markers; inducible nitric oxide synthase (iNOS) and nuclear factor kappa beta (NF-κB) were further analyzed. A host of transduction genes that regulate spermatogenic and steroidogenic pathways, and their encoded proteins namely, Steroidogenic Acute Regulatory Protein (StAR), Fatty acid binding protein 9 (FABP9) and P38-mitogen activated protein kinase (P38-MAPK) were assessed by real time quantitative (RT-qPCR) and Western blot. LC improved rat spermiogram, testicular histological alterations and endocrine perturbances, and modulated genes' expressions and their respective proteins. In conclusion, LC effects appear to reside for the most part on its endocrine-preserving, anti-oxidant and anti-inflammatory properties through a myriad of interlaced signal transductions that ultimately recapitulated its beneficial effects on spermatogenesis and steroidogenesis.

Regulatory Functions of L-Carnitine, Acetyl, and Propionyl L-Carnitine in a PCOS Mouse Model: Focus on Antioxidant/Antiglycative Molecular Pathways in the Ovarian Microenvironment

Polycystic ovary syndrome (PCOS) is a complex metabolic disorder associated with female infertility. Based on energy and antioxidant regulatory functions of carnitines, we investigated whether acyl-L-carnitines improve PCOS phenotype in a mouse model induced by dehydroepiandrosterone (DHEA). CD1 mice received DHEA for 20 days along with two different carnitine formulations: one containing L-carnitine (LC) and acetyl-L-carnitine (ALC), and the other one containing also propionyl-L-carnitine (PLC). We evaluated estrous cyclicity, testosterone level, ovarian follicle health, ovulation rate and oocyte quality, collagen deposition, lipid droplets, and 17ß-HSD IV (17 beta-hydroxysteroid dehydrogenase type IV) expression. Moreover, we analyzed protein expression of SIRT1, SIRT3, SOD2 (superoxide dismutase 2), mitochondrial transcriptional factor A (mtTFA), RAGE (receptor for AGEs), GLO2 (glyoxalase 2) and ovarian accumulation of MG-AGEs (advanced glycation end-products formed by methylglyoxal). Both carnitine formulations ameliorated ovarian PCOS phenotype and positively modulated antioxidant molecular pathways in the ovarian microenvironment. Addition of PLC to LC-ALC formulation mitigated intraovarian MG-AGE accumulation and increased mtTFA expression. In conclusion, our study supports the hypothesis that oral administration of acyl-L-carnitines alleviates ovarian dysfunctions associated with this syndrome and that co-administration of PLC provides better activity. Molecular mechanisms underlying these effects include anti-oxidant/glycative activity and potentiation of mitochondria.

The Nutraceutical Value of Carnitine and Its Use in Dietary Supplements

Carnitine can be considered a conditionally essential nutrient for its importance in human physiology. This paper provides an updated picture of the main features of carnitine outlining its interest and possible use. Particular attention has been addressed to its beneficial properties, exploiting carnitine's properties and possible use by considering the main in vitro, in animal, and human studies. Moreover, the main aspects of carnitine-based dietary supplements have been indicated and defined with reference to their possible beneficial health properties.