Comment on ‘The effect of (<scp>l</scp>‐)carnitine on weight loss in adults: a systematic review and meta‐analysis of randomized controlled trials’

Vecchio, Fabrício Boscolo Del; Coswig, Victor Silveira; Galliano, Leony Morgana

doi:10.1111/obr.12488

Cited by 10 publications

(5 citation statements)

References 10 publications

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“…Indeed, there was pronounced 4HNE-positive immunoreactivity in HFD livers at the end of the study, and this immunoreactivity was lower in the COMBI group indicating reduced oxidative stress-associated lipid peroxidation [13]. We found that mono-treatment with LC did not result in a significant reduction in body weight and fat mass, and similar findings were reported by others studying body composition in rodents [20,21,22] or BMI in healthy and obese humans [23]. Also, short time studies using NR up to 15 weeks in rodents [20,24] and up to 12 weeks humans [25,26,27,28] did not report effects on body weight or body composition.…”

Section: Discussionsupporting

confidence: 88%

Combined Treatment with L-Carnitine and Nicotinamide Riboside Improves Hepatic Metabolism and Attenuates Obesity and Liver Steatosis

Salic

Gart

Seidel

et al. 2019

IJMS

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Obesity characterized by adiposity and ectopic fat accumulation is associated with the development of non-alcoholic fatty liver disease (NAFLD). Treatments that stimulate lipid utilization may prevent the development of obesity and comorbidities. This study evaluated the potential anti-obesogenic hepatoprotective effects of combined treatment with L-carnitine and nicotinamide riboside, i.e., components that can enhance fatty acid transfer across the inner mitochondrial membrane and increase nicotinamide adenine nucleotide (NAD+) levels, which are necessary for β-oxidation and the TCA cycle, respectively. Ldlr −/−.Leiden mice were treated with high-fat diet (HFD) supplemented with L-carnitine (LC; 0.4% w/w), nicotinamide riboside (NR; 0.3% w/w) or both (COMBI) for 21 weeks. L-carnitine plasma levels were reduced by HFD and normalized by LC. NR supplementation raised its plasma metabolite levels demonstrating effective delivery. Although food intake and ambulatory activity were comparable in all groups, COMBI treatment significantly attenuated HFD-induced body weight gain, fat mass gain (−17%) and hepatic steatosis (−22%). Also, NR and COMBI reduced hepatic 4-hydroxynonenal adducts. Upstream-regulator gene analysis demonstrated that COMBI reversed detrimental effects of HFD on liver metabolism pathways and associated regulators, e.g., ACOX, SCAP, SREBF, PPARGC1B, and INSR. Combination treatment with LC and NR exerts protective effects on metabolic pathways and constitutes a new approach to attenuate HFD-induced obesity and NAFLD.

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Section: Discussionsupporting

confidence: 88%

Combined Treatment with L-Carnitine and Nicotinamide Riboside Improves Hepatic Metabolism and Attenuates Obesity and Liver Steatosis

Salic

Gart

Seidel

et al. 2019

IJMS

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“…In a recent meta-analysis, Pooyandjoo et al [ 36 ] calculated that subjects supplemented with l -carnitine lost significantly more weight (−1.33 kg), compared with the control group. This article was later criticized [ 37 ] for mixing studies using l -carnitine alone or in association with other factors (i.e., pharmacological therapy-sibutramine [ 38 ] or orlistat [ 39 ] and changes in lifestyle–diet intervention [ 40 ]). Inclusion of the studies using treatments consisting exclusively of l -carnitine indicated no modification in body weight [ 37 ].…”

Section: Discussionmentioning

confidence: 99%

“…This article was later criticized [ 37 ] for mixing studies using l -carnitine alone or in association with other factors (i.e., pharmacological therapy-sibutramine [ 38 ] or orlistat [ 39 ] and changes in lifestyle–diet intervention [ 40 ]). Inclusion of the studies using treatments consisting exclusively of l -carnitine indicated no modification in body weight [ 37 ]. Twenty-four weeks of l -carnitine supplementation, without changing nutritional or physical activity habits, did not influence our participants’ body weight.…”

Section: Discussionmentioning

confidence: 99%

l-Carnitine Supplementation in Older Women. A Pilot Study on Aging Skeletal Muscle Mass and Function

et al. 2018

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Skeletal muscle wasting, associated with aging, may be regulated by the inflammatory cytokines as well as by insulin-like growth factor 1 (IGF-1). l-carnitine possesses anti-inflammatory properties and increases plasma IGF-1 concentration, leading to the regulation of the genes responsible for protein catabolism and anabolism. The purpose of the present study was to evaluate the effect of a 24-week l-carnitine supplementation on serum inflammatory markers, IGF-1, body composition and skeletal muscle strength in healthy human subjects over 65 years of age. Women between 65 and 70 years of age were supplemented for 24 weeks with either 1500 mg l-carnitine-l-tartrate or an isonitrogenous placebo per day in a double-blind fashion. Before and after the supplementation protocol, body mass and composition, as well as knee extensor and flexor muscle strength were determined. In the blood samples, free carnitine, interleukin-6, tumor necrosis factor-α, C-reactive protein and IGF-1 were determined. A marked increase in free plasma carnitine concentration was observed due to l-carnitine supplementation. No substantial changes in other parameters were noted. In the current study, supplementation for 24 weeks affected neither the skeletal muscle strength nor circulating markers in healthy women over 65 years of age. Positive and negative aspects of l-carnitine supplementation need to be clarified.

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“…The mechanisms mediating the differential effect of acetyl‐carnitine according to the degree of glucose disposal are unclear . A meta‐analysis of randomized controlled trials analyzing the effect of l ‐carnitine on weight loss might suggest that l ‐carnitine supplementation results in weight loss in adults .…”

Section: Primary L‐carnitine Deficiencymentioning

confidence: 99%

Significance of l‐carnitine for human health

Adeva‐Andany¹,

Calvo‐Castro²,

et al. 2017

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Carnitine acyltransferases catalyze the reversible transfer of acyl groups from acyl-coenzyme A esters to l-carnitine, forming acyl-carnitine esters that may be transported across cell membranes. l-Carnitine is a wáter-soluble compound that humans may obtain both by food ingestion and endogenous synthesis from trimethyl-lysine. Most l-carnitine is intracellular, being present predominantly in liver, skeletal muscle, heart and kidney. The organic cation transporter-2 facilitates l-carnitine uptake inside cells. Congenital dysfunction of this transporter causes primary l-carnitine deficiency. Carnitine acetyltransferase is involved in the export of excess acetyl groups from the mitochondria and in acetylation reactions that regulate gene transcription and enzyme activity. Carnitine octanoyltransferase is a peroxysomal enzyme required for the complete oxidation of very long-chain fatty acids and phytanic acid, a branched-chain fatty acid. Carnitine palmitoyltransferase-1 is a transmembrane protein located on the outer mitochondrial membrane where it catalyzes the conversion of acyl-coenzyme A esters to acyl-carnitine esters. Carnitine acyl-carnitine translocase transports acyl-carnitine esters across the inner mitochondrial membrane in exchange for free l-carnitine that exits the mitochondrial matrix. Carnitine palmitoyltransferase-2 is anchored on the matrix side of the inner mitochondrial membrane, where it converts acyl-carnitine esters back to acyl-coenzyme A esters, which may be used in metabolic pathways, such as mitochondrial β-oxidation. l-Carnitine enhances nonoxidative glucose disposal under euglycemic hyperinsulinemic conditions in both healthy individuals and patients with type 2 diabetes, suggesting that l-carnitine strengthens insulin effect on glycogen storage. The plasma level of acyl-carnitine esters, primarily acetyl-carnitine, increases during diabetic ketoacidosis, fasting, and physical activity, particularly high-intensity exercise. Plasma concentration of free l-carnitine decreases simultaneously under these conditions. © 2017 IUBMB Life, 69(8):578-594, 2017.

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Comment on ‘The effect of (l‐)carnitine on weight loss in adults: a systematic review and meta‐analysis of randomized controlled trials’

Cited by 10 publications

References 10 publications

Combined Treatment with L-Carnitine and Nicotinamide Riboside Improves Hepatic Metabolism and Attenuates Obesity and Liver Steatosis

Combined Treatment with L-Carnitine and Nicotinamide Riboside Improves Hepatic Metabolism and Attenuates Obesity and Liver Steatosis

l-Carnitine Supplementation in Older Women. A Pilot Study on Aging Skeletal Muscle Mass and Function

Significance of l‐carnitine for human health

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