Virmani MA, Cirulli M. The Role of l-Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation.Int J Mol Sci. 2022;23(5):2717. Published 2022 Feb 28. doi:10.3390/ijms23052717
Publication Date: "28 February 2022"
Peer Reviewed: Yes
Study Design: "Review"
Methodology: Literature review of various studies on l-carnitine.
Sample Size: Not applicable (review study).
Controls Used: Not applicable (review study).
Dose Used: Not specified in the review.
Statistical Significance Declared: Not applicable (review study).
Adverse Events due to Acetyl-L-Carnitine Supplementation: None reported.
Conflict of Interest: "The authors declare no conflict of interest."

Dahash BA, Sankararaman S. Carnitine Deficiency. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.Available from: https://www.ncbi.nlm.nih.gov/books/NBK559041/
Publication Date: "Last Update: August 7, 2023."
Peer Reviewed: Yes.
Study Design: Review.
Methodology: The study reviews causes, pathophysiology, clinical presentation, evaluation, and treatment strategies of carnitine deficiency. Genetic testing, plasma carnitine level measurement, and various biochemical tests were mentioned.
Sample Size: Not stated in the provided text.
Controls Used: Not stated in the provided text.
Dose Used: "100 to 200 mg/kg daily dose in 3 divided doses."
Statistical Significance Declared: Not stated in the provided text.
Adverse Events due to Acetyl-L-Carnitine Supplementation: "Few side effects associated with high doses include diarrhea and intestinal discomfort. Additionally, bacterial degradation of unabsorbed oral L-carnitine in the bowel results in trimethylamine, which has a peculiar fishy odor."
Conflict of Interest: Not stated in the provided text.

Traina G. The neurobiology of acetyl-L-carnitine.Front Biosci (Landmark Ed). 2016;21(7):1314-1329. Published 2016 Jun 1. doi:10.2741/4459
Publication Date: "June 1, 2016"
Peer Reviewed: Yes
Study Design: "Review of current state of knowledge on effects of ALC in the nervous system."
Methodology: Review of multiple studies on ALC effects, involving both preclinical and clinical studies, animal models, and in vitro experiments.
Sample Size: Not applicable (review study).
Controls Used: Not applicable (review study).
Dose Used: "The dosage varied across different studies, with no specific dosage provided in the review."
Statistical Significance Declared: Not applicable (review study).
Adverse Events due to Acetyl-L-Carnitine Supplementation: "ALC is widespread in the medical practice since it is highly tolerated and without any adverse effects."
Conflict of Interest: "None declared."

Stefan M, Sharp M, Gheith R, et al. L-Carnitine Tartrate Supplementation for 5 Weeks Improves Exercise Recovery in Men and Women: A Randomized, Double-Blind, Placebo-Controlled Trial.Nutrients. 2021;13(10):3432. Published 2021 Sep 28. doi:10.3390/nu13103432
Publication Date: "28 September 2021".
Peer Reviewed: Yes.
Study Design: "Randomized, double-blind, placebo-controlled trial".
Methodology: 80 participants (21-65 years) randomized into L-carnitine tartrate or placebo groups, with a 5-week supplementation and exercise regimen, followed by assessments of recovery and muscle damage.
Sample Size: "Eighty participants".
Controls Used: "Microcrystalline Cellulose-Based Placebo".
Dose Used: "3 g of Carnipure® carnitine tartrate in 3 total capsules, yielding 2 g of elemental L-carnitine".
Statistical Significance Declared: "p = 0.021" (perceived recovery and soreness), "p = 0.016" (serum creatine kinase), "p < 0.001" (serum superoxide dismutase), "p < 0.001" (serum CRP).
Adverse Events due to Acetyl-L-Carnitine Supplementation: "adverse events did not appear to be related to supplementation.".
Conflict of Interest: "S.D. and A.B. are employees of Lonza Consumer Health Inc."

Natarajan V, Chawla R, Mah T, et al. Mitochondrial Dysfunction in Age-Related Metabolic Disorders.Proteomics. 2020;20(5-6)

. doi:10.1002/pmic.201800404

Publication Date: "First published: 04 March 2020"

Peer Reviewed: Yes

Study Design: "This review focuses on various aspects of basic mitochondrial biology and its status in aging and age-related metabolic diseases."

Methodology: Literature review of existing studies on mitochondrial dysfunction and therapies, focusing on aging and metabolic disorders.

Sample Size: Not applicable (review study).

Controls Used: Not applicable (review study).

Dose Used: Not applicable (review study).

Statistical Significance Declared: Not applicable (review study).

Adverse Events due to Acetyl-L-Carnitine Supplementation: "High doses of Acetyl-L-Carnitine may lead to gastrointestinal discomfort." "Some studies have reported an increase in agitation and restlessness with ALC use." No other adverse events were directly linked to ALC supplementation in the reviewed studies.

Conflict of Interest: "The authors declare no conflict of interest."

Wang ZY, Liu YY, Liu GH, Lu HB, Mao CY. l-Carnitine and heart disease.Life Sci. 2018;194:88-97. doi:10.1016/j.lfs.2017.12.015
Publication Date: "Available online 11 December 2017"
Peer Reviewed: Yes.
Study Design: "review"
Methodology: Literature review and meta-analyses.
Sample Size: Not applicable (review study).
Controls Used: Placebo.
Dose Used: Not applicable (review study).
Statistical Significance Declared: Not applicable (review study).
Adverse Events due to Acetyl-L-Carnitine Supplementation: None declared specifically for Acetyl-L-Carnitine, related to the broader category of carnitine and its forms.
Conflict of Interest: "The authors declare that there are no conflicts of interest."

Pennisi M, Lanza G, Cantone M, et al. Acetyl-L-Carnitine in Dementia and Other Cognitive Disorders: A Critical Update.Nutrients. 2020;12(5):1389. Published 2020 May 12. doi:10.3390/nu12051389
Publication Date: "12 May 2020"
Peer Reviewed: Yes
Study Design: "Systematic review"
Methodology: Medline (PubMed) literature review; included studies on clinical diagnosis of dementia; excluded duplicated entries, non-English papers, non-research publications, etc.
Sample Size: "A total of 37 papers were eventually included in the qualitative synthesis."
Controls Used: "Placebo as the control in all of them, they were all randomized and double-blinded, and employed a parallel-group design."
Dose Used: "Dosage range used was between 1 and 2 g/day for 6–12 months."
Statistical Significance Declared: "A statistically significant slowed deterioration rate in various aspects of cognitive function and psychometric measures, with a good tolerability." "Significant differences existed in memory, number, and word tests in the treated group." "Statistically significant effect both at 8 weeks (on the EEG) and 12 weeks of treatment (on the physician’s CGI and the patient-rated level of Activities of Daily Living) in favor of the treated group."
Adverse Events due to Acetyl-L-Carnitine Supplementation: "The commonly reported adverse reactions included nausea, agitation, insomnia, and increased appetite." No significant side effects were noted in most studies, even for long periods (one year).
Conflict of Interest: "The authors declare no conflict of interest."

Talenezhad N, Mohammadi M, Ramezani-Jolfaie N, Mozaffari-Khosravi H, Salehi-Abargouei A. Effects of l-carnitine supplementation on weight loss and body composition: A systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis.Clin Nutr ESPEN. 2020;37:9-23. doi:10.1016/j.clnesp.2020.03.008
Publication Date: "Available online 18 April 2020"
Peer Reviewed: Yes
Study Design: "Review"
Methodology: Systematic review and meta-analysis based on PRISMA guidelines, comprehensive literature search in PubMed/Medline, Scopus, Web of Sciences, and Google Scholar up to January 2019 without restrictions, using specific MeSH and non-MeSH keywords.
Sample Size: "2292 participants"
Controls Used: Various, including placebo, low-calorie diet, exercise, weight loss drug
Dose Used: Various, "2000 mg/day was the most commonly dose which was used for intervention."
Statistical Significance Declared: "P < 0.001" for weight reduction, "P = 0.001" for BMI reduction, "P = 0.003" for fat mass reduction.
Adverse Events due to Acetyl-L-Carnitine Supplementation: "nausea, stomach discomfort (2 g/d) and production of trimethylamine-N-oxide (TMAO is linked to an increased risk of atherosclerosis)."
Conflict of Interest: "The authors declare that they have no conflict of interest."

Pooyandjoo M, Nouhi M, Shab-Bidar S, Djafarian K, Olyaeemanesh A. The effect of (L-)carnitine on weight loss in adults: a systematic review and meta-analysis of randomized controlled trials.Obes Rev. 2016;17(10):970-976. doi:10.1111/obr.12436
Publication Date: "October 2016".
Peer Reviewed: Yes.
Study Design: "Systematic review and meta-analysis of randomized controlled trials"
Methodology: Systematic search of PubMed, Embase, Cochrane Central Register of Controlled Trials, and reference lists. Pooling trials with mean difference (MD) of 95% confidence interval (CI) using random effect model. Meta-regression analysis for duration of consumption.
Sample Size: "Total n = 911"
Controls Used: "Placebo"
Dose Used: "1.8 g d−1 to 4 g d−1"
Statistical Significance Declared: "MD: −1.33 kg; 95% CI: −2.09 to −0.57 for weight loss" "MD: −0.47 kg m−2; 95% CI: −0.88 to −0.05 for BMI" "p = 0.002 for duration of consumption" "p = 0.972 for dose of carnitine"
Adverse Events due to Acetyl-L-Carnitine Supplementation: "No side effects such as gastrointestinal issues, rising blood pressure, and pulse rate and increased risk of psychological disorder."
Conflict of Interest: "The authors declared that they have no potential conflicts of interest."

Yang Y, Choi H, Lee CN, Kim YB, Kwak YT. A Multicenter, Randomized, Double-blind, Placebo-controlled Clinical Trial for Efficacy of Acetyl-L-carnitine in Patients with Dementia Associated with Cerebrovascular Disease.Dement Neurocogn Disord. 2018;17(1):1-10. doi:10.12779/dnd.2018.17.1.1
Publication Date: "2018 Mar 31."
Peer Reviewed: Yes.
Study Design: "randomized, double-blind, placebo-controlled trial"
Methodology: "Fifty-six patients were randomized to treatment with 500 mg ter in die ALC, or placebo in this 28-week, double-blind, placebo-controlled trial."
Sample Size: "56 patients"
Controls Used: "placebo"
Dose Used: "1,500 mg/day"
Statistical Significance Declared: "MoCA-K 0.010", "attention 0.025", "language 0.012", "CDR-SB 0.029", "K-IADL 0.003"
Adverse Events due to Acetyl-L-Carnitine Supplementation: "One patient in the ALC-treated group died during the study and this death was considered to be unrelated to the study medication." "Other symptoms also were considered not related to ALC, and these symptoms disappeared without dosage controls."
Conflict of Interest: "The authors have no financial conflicts of interest."

Asadi M, Rahimlou M, Shishehbor F, Mansoori A. 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.Clin Nutr. 2020;39(1):110-122. doi:10.1016/j.clnu.2019.01.020
Publication Date: "Received 7 February 2018, Accepted 19 January 2019, Available online 22 February 2019, Version of Record 27 December 2019"
Peer Reviewed: Yes
Study Design: "Meta-analyses"
Methodology: Searched multiple databases for RCTs on the effect of l-carnitine on lipid profile and glycaemic control; performed meta-analysis in a random-effects model.
Sample Size: "1569 participants took part in 24 studies with 25 treatment arms including 780 subjects in the control group and 789 subjects in the l-carnitine group"
Controls Used: "Placebo", "Simvastatin", "Placebo + Diet"
Dose Used: "a broad range of dosing regimens (250–4000 mg/day)"
Statistical Significance Declared: "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)", "HOMA-IR (WMD (%) = − 0.94 [95% CI: −1.89, −0.00]; P = 0.05)"
Adverse Events due to Acetyl-L-Carnitine Supplementation: "Included studies in the meta-analysis no reported any significant side effects during l-carnitine supplementation"
Conflict of Interest: "None of the authors declare a conflict of interest"

Zamani M, Pahlavani N, Nikbaf-Shandiz M, et al. The effects of L-carnitine supplementation on glycemic markers in adults: A systematic review and dose-response meta-analysis.Front Nutr. 2023;9:1082097. Published 2023 Jan 10. doi:10.3389/fnut.2022.1082097
Publication Date: "October 2022"
Peer Reviewed: Yes
Study Design: Systematic review
Methodology: PubMed, Scopus, Web of Science, and the Cochrane databases were searched in October 2022 for prospective studies on the effects of L-carnitine supplementation on glycemic markers. Inclusion criteria included adult participants and taking oral L-carnitine supplements for at least seven days. The pooled weighted mean difference (WMD) was calculated using a random-effects model.
Sample Size: "n = 2900"
Controls Used: "Placebo"
Dose Used: "0.25 to 4 g/day"
Statistical Significance Declared: "FBG (mg/dl) [WMD = −3.22 mg/dl; 95% CI, −5.21 to −1.23; p = 0.002; I2 = 88.6%, p < 0.001], HbA1c (%) [WMD = −0.27%; 95% CI, −0.47 to −0.07; p = 0.007; I2 = 90.1%, p < 0.001], HOMA-IR [WMD = −0.73; 95% CI, −1.21 to −0.25; p = 0.003; I2 = 98.2%, p < 0.001]"
Adverse Events due to Acetyl-L-Carnitine Supplementation: "Adverse effects were mentioned in the studies by Derosa et al. (Flatulence, Constipation, abdominal pain, fatty/oily evacuation, increased defecation, fecal urgency, malaise), Hong et al. (musculoskeletal pain and gastrointestinal disturbance), Malaguarnera et al. (gastrointestinal tract complaints) and An et al. (nausea, generalized edema, epigastric discomfort)"
Conflict of Interest: "The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest"

Veronese N, Stubbs B, Solmi M, Ajnakina O, Carvalho AF, Maggi S. Acetyl-L-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis.Psychosom Med. 2018;80(2):154-159. doi:10.1097/PSY.0000000000000537
Publication Date: "Received Date: May 6, 2017"
Peer Reviewed: No
Study Design: "randomized controlled trials (RCTs)"
Methodology: Literature search, inclusion criteria for RCTs, data extraction, assessment of study quality, data synthesis and statistical analysis.
Sample Size: "Twelve RCTs (11 of which were ALC monotherapy) with a total of 791 participants"
Controls Used: "a control group taking placebo/no intervention or antidepressants"
Dose Used: "3 grams of ALC"
Statistical Significance Declared: "ALC significantly reduced depressive symptoms (SMD=-1.10; 95%CI: -1.65 to -0.56; I2=86%)" "ALC demonstrated similar effectiveness compared to established antidepressants in reducing depressive symptoms (SMD=0.06; 95%CI: -0.22 to 0.34; I2=31%)" "a significant reduction of 79% in side effects when compared to antidepressants (OR=0.21; 95%CI: 0.12-0.36; p<. 001)"
Adverse Events due to Acetyl-L-Carnitine Supplementation: "The incidence of side effects was significantly lower in ALC than the antidepressant group." "the frequency of side effects was similar between treated with ALC and controls" "a significantly reduced risk of side effects (OR=0.21; 95%CI: 0.12-0.36; p<. 001) compared to antidepressants"
Conflict of Interest: "The authors declare no conflict of interest."

Sawicka AK, Renzi G, Olek RA. The bright and the dark sides of L-carnitine supplementation: a systematic review.J Int Soc Sports Nutr. 2020;17(1):49. Published 2020 Sep 21. doi:10.1186/s12970-020-00377-2
Publication Date: "Published online 2020 Sep 21."
Peer Reviewed: Yes
Study Design: "Randomized controlled trials, non-randomized controlled trials, non-randomized non-controlled trials."
Methodology: Literature search in MEDLINE and Web of Science databases, inclusion/exclusion criteria applied, studies with healthy human subjects, treated for at least 12 weeks with oral LC.
Sample Size: "7 to 27 participants per study."
Controls Used: "Placebo, control, pre- and post-supplementation."
Dose Used: "1 g to 4 g per day for either 12 or 24 weeks."
Statistical Significance Declared: "Muscle TC concentration tend to increase after LC supplementation (p = 0.06 vs. pre-supplementation)."
Adverse Events due to Acetyl-L-Carnitine Supplementation: "No adverse events associated with LC administration were recorded at a dose 6 g/day for 12 months of supplementation."
Conflict of Interest: "The authors declare that they have no competing interests."

Badrasawi M, Shahar S, Zahara AM, Nor Fadilah R, Singh DK. Efficacy of L-carnitine supplementation on frailty status and its biomarkers, nutritional status, and physical and cognitive function among prefrail older adults: a double-blind, randomized, placebo-controlled clinical trial.Clin Interv Aging. 2016;11:1675-1686. Published 2016 Nov 17. doi:10.2147/CIA.S113287
Publication Date: "Published online 2020 Sep 21."
Peer Reviewed: Yes
Study Design: "Randomized controlled trials, non-randomized controlled trials, non-randomized non-controlled trials."
Methodology: Literature search in MEDLINE and Web of Science, studies on healthy human subjects, treated for at least 12 weeks with LC administered orally, no drugs or multi-ingredient supplements co-ingestion.
Sample Size: "Total of 11 studies."
Controls Used: "Placebo, control, or pre- and post- supplementation."
Dose Used: "Ranging from 1 g to 4.5 g per day for either 12 or 24 weeks."
Statistical Significance Declared: "p = 0.06 vs. pre-supplementation" (specific values for various outcomes).
Adverse Events due to Acetyl-L-Carnitine Supplementation: "Elevates fasting plasma TMAO" (associated with pro-atherogenic risk). No other adverse events directly linked to LC.
Conflict of Interest: "The authors declare that they have no competing interests."

Clark RM, Balakrishnan A, Waters D, Aggarwal D, Owen KQ, Koo SI. L-carnitine increases liver alpha-tocopherol and lowers liver and plasma triglycerides in aging ovariectomized rats.J Nutr Biochem. 2007;18(9):623-628. doi:10.1016/j.jnutbio.2006.11.007
Publication Date: "Available online 21 March 2007."
Peer Reviewed: Yes.
Study Design: "Research Article"
Methodology: 18-month-old female Fisher 344 rats acclimated for 4 weeks, ovariectomized, divided into control and carnitine groups, fed for 8 weeks, blood and tissues analyzed, no differences in food intake, body weight, organ weights.
Sample Size: "Fourteen Fisher-344 female rats 18 months old."
Controls Used: "A control group fed AIN-93M diet containing no supplemental carnitine."
Dose Used: "150 mg l-carnitine l-tartrate (l-Carnipure tartrate; Lonza, Allendale, NJ, USA) per kilogram of diet."
Statistical Significance Declared: "Dietary carnitine... tended to increase plasma α-tocopherol (P<.09)." "The liver concentration of TG was reduced by 33%... P<.01." "The liver concentration of α-tocopherol increased by 72%... P<.01." "The plasma level of TG was significantly lower in response to carnitine feeding (P<.01)."
Adverse Events due to Acetyl-L-Carnitine Supplementation: "One of the animals in the carnitine group was eliminated from the experiment because of reduced food intake and weight gain during the last 2 weeks of the feeding period."
Conflict of Interest: "We thank Lonza (Allendale, NJ, USA) for providing l-carnitine (l-Carnipure tartrate) for the study."

Olek, R.A., Samborowska, E., Wisniewski, P.et al.Effect of a 3-month L-carnitine supplementation and resistance training program on circulating markers and bone mineral density in postmenopausal women: a randomized controlled trial.Nutr Metab (Lond)20, 32 (2023). https://doi.org/10.1186/s12986-023-00752-1
Publication Date: "Available online 21 March 2007."
Peer Reviewed: Yes.
Study Design: "Randomly assigned to either a control group fed ad libitum AIN-93M diet or a carnitine group fed the same diet supplemented with l-carnitine."
Methodology: Female Fisher-344 rats 18 months old, acclimated for 4 weeks, ovariectomized, randomly assigned to control or carnitine diet groups, 8-week feeding period, blood and tissue analyses, monitored daily food consumption and body weight.
Sample Size: "Fourteen Fisher-344 female rats."
Controls Used: "Control group fed ad libitum AIN-93M diet."
Dose Used: "150 mg l-carnitine l-tartrate (l-Carnipure tartrate; Lonza, Allendale, NJ, USA) per kilogram of diet."
Statistical Significance Declared: "Plasma TG (P<.05)." "Liver total TG (P<.01)." "Liver α-tocopherol (P<.01)." "Plasma α-tocopherol (P<.09)."
Adverse Events due to Acetyl-L-Carnitine Supplementation: "No differences were noted in food intake, body weight, or organ weights due to l-carnitine." "Retinol levels inplasma and tissues were not affected by supplemental l-carnitine." "No differences were observed in the fatty acid profile of tissues."
Conflict of Interest: "We thank Lonza (Allendale, NJ, USA) for providing l-carnitine (l-Carnipure tartrate) for the study."

Olek RA, Samborowska E, Wisniewski P, et al. Effect of a 3-month L-carnitine supplementation and resistance training program on circulating markers and bone mineral density in postmenopausal women: a randomized controlled trial. Nutr Metab (Lond). 2023;20:32. https://doi.org/10.1186/s12986-023-00752-1
Publication Date: "Available online 21 March 2023."
Peer Reviewed: Yes
Study Design: "Randomly assigned to either a control group fed ad libitum AIN-93M diet or a carnitine group fed the same diet supplemented with l-carnitine."
Methodology: Female Fisher-344 rats 18 months old, acclimated for 4 weeks, ovariectomized, randomly assigned to control or carnitine diet groups, 8-week feeding period, blood and tissue analyses, monitored daily food consumption and body weight.
Sample Size: "Fourteen Fisher-344 female rats."
Controls Used: "Control group fed ad libitum AIN-93M diet."
Dose Used: "150 mg l-carnitine l-tartrate (l-Carnipure tartrate; Lonza, Allendale, NJ, USA) per kilogram of diet."
Statistical Significance Declared: "Plasma TG (P<.05)." "Liver total TG (P<.01)." "Liver α-tocopherol (P<.01)." "Plasma α-tocopherol (P<.09)."
Adverse Events due to Acetyl-L-Carnitine Supplementation: "No differences were noted in food intake, body weight, or organ weights due to l-carnitine." "Retinol levels in plasma and tissues were not affected by supplemental l-carnitine." "No differences were observed in the fatty acid profile of tissues."
Conflict of Interest: "We thank Lonza (Allendale, NJ, USA) for providing l-carnitine (l-Carnipure tartrate) for the study."