Acetyl-L-Carnitine
Acetyl-L-carnitine (ALCAR) supports mitochondrial fatty-acid metabolism. Possible benefits for depression and neuropathy are strongest in older adults.
Overview
What is Acetyl-L-carnitine?
Acetyl-L-carnitine (ALCAR) is an acetylated form of L-carnitine that may improve brain function and symptoms of depression, especially in older adults.
A carnitine ester, acetyl-L-carnitine is required for healthy mitochondrial function and helps to break down fatty acids in the body.
The body maintains a pool of carnitine and acylcarnitines and can convert between acetyl-L-carnitine and L-carnitine.
Dosage
A typical safe dose of acetyl-L-carnitine is around 2000 mg per day for most people.
Studies using acetyl-L-carnitine for brain health and function use doses ranging from 500 to 3000 mg per day.
Effect graph
Effect heatmap
SupplementDEX Database
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Database Snapshot
Most acetyl-l-carnitine research is concentrated in a handful of conditions.
- Male infertility accounts for 15 of 76 studies (20%).
- Alzheimer's disease accounts for 8 of 76 studies (11%).
- Age-related cognitive decline accounts for 7 of 76 studies (9%).
- Sparse coverage remains for Athletic performance, Attention deficit-hyperactivity disorder (ADHD), Carpal tunnel syndrome.
Dietary Sources
Top dietary sources
Daily Value: 15 mg per day
Ranked by amount per 100 g
The western diet provides around 24 to 145 mg carnitine per day. A typical vegan diet provides around 1.2 mg per day.
- 637 mg100 g4247% DV
- 423 mg100 g2820% DV
- 396 mg100 g2640% DV
- 226 mg100 g1507% DV
- 200 mg100 g1333% DV
- 190 mg100 g1267% DV
- 183 mg100 g1220% DV
- 139 mg100 g927% DV
Other sources include Cow/goat Milk-Based Infant Formula, Follow-On Infant Formula, Lactose-Free Infant Formula, Protein-Hydrolysed Infant Formula, and Soya-Based Infant Formula.
Safety
Studies have safely used higher doses of up to 3000 mg per day for 8 weeks to 12 months.[74][38]
Dose windows
Special populations
Pregnancy & breastfeeding
AvoidIn pregnant or lactating women, the effects of acetyl-L-carnitine supplementation have not been well studied. Usage should be avoided.
Children
Likely safeIn children, doses of 500 mg to 1500 mg per day have been safely used for 6 weeks.[50]
Frequently Asked Questions
Takeaway
Acetyl-L-carnitine is an organic compound produced naturally in the body that is required for healthy mitochondrial function. ALCAR may have benefits for depression and selected neurological outcomes, but many benefits are clearest in older adults or clinical subgroups. Low blood levels of acetyl-L-carnitine are associated with worsened depression symptoms in some research.
References
Sources90 references
SupplementDEX uses only high-quality sources to determine supplement effectiveness.
SupplementDEX Database · Depression
4 references1.SupplementDEX Database: Depression — Acetyl-L-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis2018
A meta-analysis of ALC trials (791 participants) found acetyl-L-carnitine supplementation reduced depressive symptoms versus control with moderate effect sizes.
2.SupplementDEX Database: Depression — Effect of acetyl-L-carnitine on geriatric patients suffering from dysthymic disorders1990
Sixty patients aged 60–80 years with dysthymic disorders (DSM III) were randomized to acetyl-L-carnitine 3 g/day orally or placebo. After a 1-week washout, participants were assessed with the Hamilton Rating Scale for Depression, Beck Depression Inventory, and Sandoz Clinical Assessment–Geriatric at baseline and after 30 and 60 days. Acetyl-L-carnitine significantly reduced depressive symptom severity versus placebo (p<0.002) and significantly improved quality-of-life items (p<0.0027).
3.SupplementDEX Database: Depression — Evaluation of the effects of L-acetylcarnitine on senile patients suffering from depression1990
Twenty-eight patients aged 70–80 years with depression (DSM III R, cat. 300.40) were randomized to two groups of 14: L-acetylcarnitine 500 mg three times daily or placebo. Outcomes were assessed with the Hamilton Rating Scale for Depression, Beck Depression Inventory, Sandoz Clinical Assessment–Geriatric, and clinical global impression. L-acetylcarnitine was effective in reducing depressive symptoms, with decreased Hamilton and Beck scores and beneficial effects on behavioural aspects.
4.SupplementDEX Database: Depression — L-acetylcarnitine in depressed elderly subjects. A cross-over study vs placebo1987
An open crossover trial in 24 hospitalized geriatric patients with depression found acetylcarnitine for 1 month significantly reduced depressive symptoms, especially in patients with more severe baseline scores.
SupplementDEX Database · Diabetic neuropathy
6 references5.SupplementDEX Database: Diabetic neuropathy — Acetyl-L-carnitine for the treatment of diabetic peripheral neuropathy2019
Cochrane systematic review of four RCTs with 907 participants (three ALC vs placebo, one ALC vs methylcobalamin). Doses ranged from 1500 to 3000 mg/day ALC. ALC reduced pain versus placebo on a 0–100 mm VAS (MD −9.16 mm, 95% CI −16.76 to −1.57; 3 studies, 540 participants; very low-certainty evidence). In subgroup analysis, doses >1500 mg/day showed greater pain reduction than placebo (MD −14.93 mm); at ≤1500 mg/day there was little difference from placebo. Vibration perception improved in two placebo-controlled studies at 12 months. The authors concluded that evidence is very uncertain due to sparsity and low certainty.
6.SupplementDEX Database: Diabetic neuropathy — Effects of acetyl-L-carnitine and methylcobalamin for diabetic peripheral neuropathy: A multicenter, randomized, double-blind, controlled trial2016
In 232 diabetic peripheral neuropathy patients, 500 mg acetyl-L-carnitine three times daily for 24 weeks was non-inferior to methylcobalamin for neuropathy symptoms and nerve conduction.
7.SupplementDEX Database: Diabetic neuropathy — Acetyl-L-carnitine improves pain, nerve regeneration, and vibratory perception in patients with chronic diabetic neuropathy: an analysis of two randomized placebo-controlled trials2005
Pooled analysis of two 52-week randomized, placebo-controlled trials of acetyl-L-carnitine at 500 mg/day and 1000 mg/day (both given three times daily) in 1,257 intention-to-treat patients (93% of enrolled) with established diabetic neuropathy. Outcomes included sural nerve morphometry, nerve conduction velocities, vibration perception thresholds, clinical symptom scores, and a VAS for most bothersome symptom (including pain). ALC significantly improved sural nerve fiber numbers and regenerating nerve fiber clusters; nerve conduction velocities and amplitudes did not improve, while vibration perception improved in both studies. Pain showed significant improvement in one study and in the combined cohort taking 1000 mg ALC. Conclusions: ALC alleviated symptoms (particularly pain) and improved nerve fiber regeneration and vibration perception.
8.SupplementDEX Database: Diabetic neuropathy — Acetyl-L-carnitine (levacecarnine) in the treatment of diabetic neuropathy: A long-term, randomised, double-blind, placebo-controlled study2002
Multicenter (20 sites), randomized, double-blind, placebo-controlled trial in 333 patients with clinical and/or neurophysiological diabetic neuropathy. Acetyl-L-carnitine was given as 1000 mg/day intramuscularly for 10 days, then 2000 mg/day orally for the remainder of the study (355 days total). Primary outcomes were 6- and 12-month changes in nerve conduction velocity (NCV) and amplitude (sensory and motor nerves) and pain on a visual analogue scale (VAS). Among 294 patients with impaired electrophysiology at baseline, LAC significantly improved mean NCV and amplitude versus placebo (p<0.01). Largest NCV improvements at 12 months were in sural nerve (+7 vs +1.0 m/sec), ulnar sensory (+2.9 vs +0.1 m/sec), and peroneal motor (+2.7 vs −0.2 m/sec). Mean VAS pain scores fell 39% with LAC versus 8% with placebo at 12 months. LAC was well tolerated.
9.SupplementDEX Database: Diabetic neuropathy — Acetyl-L-carnitine for symptomatic diabetic neuropathy1995
A randomized crossover trial evaluated acetyl-L-carnitine for symptomatic diabetic neuropathy; published details are limited to the title with no outcome data in the available abstract.
10.SupplementDEX Database: Diabetic neuropathy — L-acetylcarnitine as a new therapeutic approach for peripheral neuropathies with pain1995
Randomized trial in 94 patients with painful peripheral neuropathies (including diabetic neuropathy). Participants received placebo (n=31), L-acetylcarnitine hydrochloride 0.5 g/day (n=31), or 1 g/day (n=32) by daily intramuscular injection for 15 days. The 1 g/day dose was significantly better than placebo for total motility at day 15 (by intention-to-treat), visual analogue scale score, and objective and subjective efficacy ratings. The 1 g/day dose was also better than 0.5 g/day when compared with placebo. Safety and tolerability were good.
SupplementDEX Database · Male infertility
15 references11.SupplementDEX Database: Male infertility — Effect of antioxidants on semen parameters in men with oligo-astheno-teratozoospermia: a network meta-analysis2024
A network meta-analysis of 29 RCTs (2045 men, avg age 33.5) with oligo-astheno-teratozoospermia ranked L-carnitine plus L-acetylcarnitine highest for sperm concentration, progressive motility, and morphology versus placebo.
12.SupplementDEX Database: Male infertility — The Effect of Antioxidants on Sperm Quality Parameters and Pregnancy Rates for Idiopathic Male Infertility: A Network Meta-Analysis of Randomized Controlled Trials2022
A network meta-analysis of 23 RCTs (1917 patients) found L-carnitine ranked first for sperm motility and morphology and ω-3 fatty acids for concentration, but no antioxidant significantly improved pregnancy rate versus placebo.
13.SupplementDEX Database: Male infertility — The Role and Place of Antioxidants in the Treatment of Male Infertility Caused by Varicocele2022
In 163 men with idiopathic or varicocele-related infertility, 6 months of an antioxidant formula containing 3,450 mg/day L-carnitine plus acetyl-L-carnitine improved sperm count, concentration, and motility, with greatest benefit in grade III varicocele.
16.SupplementDEX Database: Male infertility — A Meta-Analysis of the Efficacy of L-Carnitine/L-Acetyl-Carnitine or N-Acetyl-Cysteine in Men With Idiopathic Asthenozoospermia2021
A meta-analysis of 7 RCTs (621 men) with asthenozoospermia found L-carnitine/L-acetylcarnitine improved sperm motility and morphology; N-acetylcysteine also improved concentration and ejaculate volume.
17.SupplementDEX Database: Male infertility — Comparison of 3- and 6-Month Outcomes of Combined Oral L-Carnitine Fumarate and Acetyl-L-Carnitine Therapy, Included in an Antioxidant Formulation, in Patients with Idiopathic Infertility2021
In 78 men with idiopathic infertility, a carnitine-containing antioxidant taken twice daily for 6 months significantly improved sperm concentration, total count, and motility at both 3 and 6 months.
14.SupplementDEX Database: Male infertility — The efficacy of combined L-carnitine and L-acetyl carnitine in men with idiopathic oligoasthenoteratozoospermia: A systematic review and meta-analysis2020
A meta-analysis of 7 RCTs (693 men) with oligoasthenoteratozoospermia found combined L-carnitine and L-acetylcarnitine increased forward motility, total motile sperm, and pregnancy rate versus placebo.
15.SupplementDEX Database: Male infertility — L-carnitine and L-acetylcarnitine supplementation for idiopathic male infertility2020
A meta-analysis of 8 RCTs found carnitine supplementation improved total and progressive sperm motility and morphology but not sperm concentration or clinical pregnancy rate.
18.SupplementDEX Database: Male infertility — Double-blind, randomised, placebo-controlled trial on the effect of L-carnitine and L-acetylcarnitine on sperm parameters in men with idiopathic oligoasthenozoospermia2019
An RCT in 175 men aged 19–44 with oligoasthenozoospermia found Proxeed Plus (L-carnitine plus L-acetylcarnitine with micronutrients) for 6 months improved progressive motility, vitality, and reduced sperm DNA fragmentation versus placebo.
19.SupplementDEX Database: Male infertility — Semen quality in patients with Chlamydia trachomatis genital infection treated concurrently with prulifloxacin and a phytotherapeutic agent2012
In 206 men with Chlamydia-associated oligoasthenoteratozoospermia, 6 months of FERTIMEV (L-arginine, L-carnitine, acetyl-L-carnitine, ginseng) plus prulifloxacin improved sperm concentration and motility more than antibiotic alone.
20.SupplementDEX Database: Male infertility — Treatment with carnitine, acetyl carnitine, L-arginine and ginseng improves sperm motility and sexual health in men with asthenozoospermia2010
An RCT in 180 men with asthenozoospermia found treatment with carnitine, acetylcarnitine, L-arginine, and ginseng significantly improved progressive sperm motility and sexual satisfaction versus no treatment.
21.SupplementDEX Database: Male infertility — Clinical efficacy of combined L-carnitine and acetyl-L-carnitine on idiopathic asthenospermia2008
A trial in 25 men with idiopathic asthenospermia found combined L-carnitine and acetyl-L-carnitine for 3 months significantly improved sperm vitality, grade a+b motility, and total sperm count.
22.SupplementDEX Database: Male infertility — Placebo-controlled double-blind randomized trial on the use of L-carnitine, L-acetylcarnitine, or combined L-carnitine and L-acetylcarnitine in men with idiopathic asthenozoospermia2005
In 59 men with asthenozoospermia, 6 months of L-carnitine, acetyl-L-carnitine, or combined therapy increased sperm motility and seminal antioxidant capacity, with acetyl-L-carnitine showing the strongest effect.
23.SupplementDEX Database: Male infertility — A placebo-controlled double-blind randomized trial of combined L-carnitine and L-acetyl-carnitine treatment in men with asthenozoospermia2004
In 56 infertile men with oligo-astheno-teratozoospermia, combined L-carnitine 2 g/day and acetyl-L-carnitine 1 g/day for 6 months significantly increased sperm motility, especially in men with lower baseline motile sperm counts.
24.SupplementDEX Database: Male infertility — Cinnoxicam and L-carnitine/acetyl-L-carnitine treatment for idiopathic and varicocele-associated oligoasthenospermia2004
In men with idiopathic or varicocele-associated oligoasthenospermia, L-carnitine plus acetyl-L-carnitine with cinnoxicam raised pregnancy rates to 38.0% versus 21.8% with carnitine alone and 1.7% with placebo over 6 months.
25.SupplementDEX Database: Male infertility — Antioxidant treatment with carnitines is effective in infertile patients with prostatovesiculoepididymitis and elevated seminal leukocyte concentrations after NSAID treatment2002
An RCT in 98 infertile men with prostatovesiculoepididymitis found carnitines after 2 months of NSAIDs produced the greatest reduction in seminal reactive oxygen species and greatest gains in sperm motility.
26.SupplementDEX Database: Age-related cognitive decline — Acetyl-L-Carnitine in Dementia and Other Cognitive Disorders: A Critical Update2020
A 2020 review of acetyl-L-carnitine studies in dementia concluded that clinical benefit remains unproven and that more homogeneous, long-term RCTs are needed before routine use.
27.SupplementDEX Database: Age-related cognitive decline — A Multicenter, Randomized, Double-blind, Placebo-controlled Clinical Trial for Efficacy of Acetyl-L-carnitine in Patients with Dementia Associated with Cerebrovascular Disease2018
A 28-week study of 52 dementia patients found that 1500 mg/day acetyl-L-carnitine improved MoCA-K scores, a measure of early dementia and cognitive impairment. However benefits were limited to improvements in attention skills and language processing with no benefits for abstraction, delayed recall, orientation, visuo-executive and naming ability.
28.SupplementDEX Database: Age-related cognitive decline — L-carnitine for cognitive enhancement in people without cognitive impairment2017
A Cochrane review of 2 RCTs in cognitively healthy young adults found no evidence that L-carnitine improved reaction time, vigilance, or memory after 3 days; overall evidence quality was very low.
29.SupplementDEX Database: Age-related cognitive decline — Meta-analysis of double blind randomized controlled clinical trials of acetyl-L-carnitine versus placebo in the treatment of mild cognitive impairment and mild Alzheimer's disease2003
A meta-analysis of double-blind RCTs (3–12 months, 1.5–3 g/day) in mild cognitive impairment and early Alzheimer's found acetyl-L-carnitine significantly improved clinical and psychometric scores versus placebo, with benefits apparent by 3 months.
30.SupplementDEX Database: Age-related cognitive decline — Acetyl-L-carnitine for dementia2003
A Cochrane review of 11 Alzheimer's trials found acetyl-L-carnitine showed no benefit on cognition, dementia severity, or functional ability, though a chance finding on clinical global impression did not support routine use.
31.SupplementDEX Database: Age-related cognitive decline — L-acetylcarnitine treatment of mental decline in the elderly1994
A single-blind trial in 481 older adults with mild mental impairment found L-acetylcarnitine 1500 mg/day for 90 days significantly improved MMSE, memory, and depression scores versus baseline.
32.SupplementDEX Database: Age-related cognitive decline — Acetyl-L-carnitine in the treatment of mildly demented elderly patients1990
An RCT in 60 mildly impaired adults over age 65 found acetyl-L-carnitine 2 g/day for 3 months significantly improved memory, attention, and behavioral scores versus placebo.
SupplementDEX Database · Age-related fatigue
1 reference33.SupplementDEX Database: Age-related fatigue — Acetyl L-carnitine (ALC) treatment in elderly patients with fatigue2008
An RCT in 96 elderly patients (avg age ~76) with chronic fatigue found acetyl-L-carnitine significantly reduced physical and mental fatigue and improved functional status and MMSE versus placebo.
SupplementDEX Database · Alcohol use disorder
3 references34.SupplementDEX Database: Alcohol use disorder — Acetyl-L-Carnitine in the treatment of anhedonia, melancholic and negative symptoms in alcohol dependent subjects2011
An RCT in 64 detoxified alcohol-dependent patients found IV acetyl-L-carnitine (1–3 g/day) for 10 days accelerated improvement in anhedonia and melancholic symptoms versus placebo; oral ALC afterward showed no further benefit.
35.SupplementDEX Database: Alcohol use disorder — Acetyl-L-carnitine for alcohol craving and relapse prevention in anhedonic alcoholics: a randomized, double-blind, placebo-controlled pilot trial2010
A pilot RCT in 64 anhedonic alcohol-dependent patients found acetyl-L-carnitine prolonged abstinence and reduced craving from day 10 versus placebo, though relapse rates at 90 days did not differ.
36.SupplementDEX Database: Alcohol use disorder — Role of acetyl-L-carnitine in the treatment of cognitive deficit in chronic alcoholism1990
An RCT in 55 abstinent alcoholics found acetyl-L-carnitine 2 g/day for 90 days significantly improved long-term memory and cognitive test performance versus placebo.
SupplementDEX Database · Alzheimer's disease
6 references37.SupplementDEX Database: Alzheimer's disease — Acetyl-L-carnitine slows decline in younger patients with Alzheimer's disease: a reanalysis of a double-blind, placebo-controlled study using the trilinear approach1998
A reanalysis of a 334-patient, 1-year Alzheimer's RCT found acetyl-L-carnitine slowed cognitive decline only in patients under age 61; overall groups declined at the same rate.
38.SupplementDEX Database: Alzheimer's disease — A 1-year multicenter placebo-controlled study of acetyl-L-carnitine in patients with Alzheimer's disease1996
A 1-year RCT in 431 mild-to-moderate Alzheimer's patients found 3 g/day acetyl-L-carnitine did not slow overall decline, though early-onset patients (≤65 years) showed a trend toward slower progression.
39.SupplementDEX Database: Alzheimer's disease — Clinical and neurochemical effects of acetyl-L-carnitine in Alzheimer's disease1995
A 1-year double-blind study in 12 probable Alzheimer's patients found acetyl-L-carnitine significantly slowed MMSE and ADAS decline and normalized brain phosphomonoester levels versus placebo.
40.SupplementDEX Database: Alzheimer's disease — Double-blind parallel design pilot study of acetyl levocarnitine in patients with Alzheimer's disease1992
A 6-month pilot RCT in 30 mild-to-moderate Alzheimer's patients found acetyl levocarnitine (2.5–3 g/day) reduced deterioration on timed cancellation and digit span versus placebo.
41.SupplementDEX Database: Alzheimer's disease — Long-term acetyl-L-carnitine treatment in Alzheimer's disease1991
A 1-year RCT in 130 Alzheimer's patients found acetyl-L-carnitine slowed deterioration on 13 of 14 outcome measures, reaching significance on Blessed Dementia Scale, logical intelligence, and selective attention.
42.SupplementDEX Database: Alzheimer's disease — Double-blind, placebo-controlled study of acetyl-L-carnitine in patients with Alzheimer's dementia1990
A 24-week RCT in 36 Alzheimer-type dementia patients found acetyl-L-carnitine 2 g/day showed trends toward better short-term memory scores, but group differences did not reach statistical significance.
SupplementDEX Database · Athletic performance
2 references43.SupplementDEX Database: Athletic performance — Effect of Acute and Chronic Oral L-Carnitine Supplementation on Exercise Performance Based on the Exercise Intensity: A Systematic Review2021
A systematic review of 11 studies found that an acute dose of 3 to 4 grams L-carnitine taken 60 to 90 minutes before a high intensity exercise (>80% VO2 max) improved peak power, average power, lactate threshold and reduced perceived exertion. A dose ranging from 2 to 2.72 g/day L-carnitine taken for 9 to 24 weeks reduced lactate accumulation, reduced perceived exertion, increased work capacity in all out efforts, increased peak power in a Wingate test, and increased number of repetitions and volume lifted in leg press exercises. However, there was no effect from a dose of 2.72 to 3 g/day L-carnitine (4 to 24 weeks) in exercise of moderate intensity (50-79% VO2 max).
44.SupplementDEX Database: Athletic performance — Effects of nine weeks L-Carnitine supplementation on exercise performance, anaerobic power, and exercise-induced oxidative stress in resistance-trained males2018
In 23 resistance-trained men, 9 weeks of L-carnitine 2 g/day increased bench press volume and peak power and reduced post-exercise blood lactate and oxidative stress markers versus placebo.
45.SupplementDEX Database: Chemotherapy-induced peripheral neuropathy — Randomized double-blind placebo-controlled trial of acetyl-L-carnitine for the prevention of taxane-induced neuropathy in women undergoing adjuvant breast cancer therapy2013
A 24-week randomized double-blind trial in 409 women undergoing adjuvant taxane-based chemotherapy compared acetyl-L-carnitine (3,000 mg/day) with placebo. There was no evidence that ALC prevented chemotherapy-induced peripheral neuropathy at 12 weeks; by 24 weeks, ALC significantly increased CIPN (scores 1.8 points lower with ALC). Patients receiving ALC were more likely to have a >5-point decrease in neurotoxicity scores (38% vs 28%), and grade 3–4 neurotoxicity was more frequent in the ALC arm (8 vs 1). The authors concluded that ALC increased CIPN and that patients should be discouraged from using supplements without proven efficacy.
46.SupplementDEX Database: Age-related testosterone deficiency — Carnitine versus androgen administration in the treatment of sexual dysfunction, depressed mood, and fatigue associated with male aging2004
An RCT in 120 men aged 60–74 found propionyl-L-carnitine plus acetyl-L-carnitine (2 g/day each) for 6 months improved erectile function and mood as well as testosterone, without raising prostate volume.
SupplementDEX Database · ALS
1 reference47.SupplementDEX Database: ALS — Randomized double-blind placebo-controlled trial of acetyl-L-carnitine for ALS2013
A 48-week pilot RCT in 82 ALS patients on riluzole found acetyl-L-carnitine 3 g/day improved ALSFRS-R and FVC scores and extended median survival (45 vs 22 months) versus placebo.
SupplementDEX Database · Atherosclerosis
1 reference48.SupplementDEX Database: Atherosclerosis — Efficacy of γ-linolenic acid, Vitis vinifera extract, and acetyl-L-carnitine combination therapy for improving arterial stiffness in Korean adults: Real-world evidence2023
A retrospective study in 318 Korean adults with high arterial stiffness found a triple combination of γ-linolenic acid, Vitis vinifera extract, and acetyl-L-carnitine reduced brachial-ankle pulse wave velocity after 1 year.
SupplementDEX Database · ADHD
2 references49.SupplementDEX Database: ADHD — Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce2022
WFSBP/CANMAT 2022 guidelines rated acetyl-L-carnitine as not recommended for ADHD based on Grade A evidence from meta-analyses and RCTs.
50.SupplementDEX Database: ADHD — Acetyl-L-carnitine as an adjunctive therapy in the treatment of attention-deficit/hyperactivity disorder in children and adolescents: a placebo-controlled trial2011
A 6-week RCT in 40 children with ADHD found acetyl-L-carnitine (500–1500 mg/day) plus methylphenidate did not improve parent or teacher ADHD ratings versus methylphenidate plus placebo.
SupplementDEX Database · Bipolar disorder
1 reference51.SupplementDEX Database: Bipolar disorder — A placebo-controlled trial of acetyl-L-carnitine and α-lipoic acid in the treatment of bipolar depression2013
A 12-week RCT in 40 patients with bipolar depression found acetyl-L-carnitine plus α-lipoic acid did not reduce depression scores versus placebo on the Montgomery-Åsberg Depression Rating Scale.
SupplementDEX Database · Carpal tunnel syndrome
2 references52.SupplementDEX Database: Carpal tunnel syndrome — Clinical usefulness of nutraceutics with acetyl-L-carnitine, α-lipoic acid, phosphatidylserine, curcumin, C, E and B-group vitamins in patients awaiting carpal tunnel release during the COVID-19 pandemic: a randomized controlled open-label prospective study2023
An open-label RCT in 147 mild-to-moderate carpal tunnel patients awaiting surgery found a nutraceutical blend with acetyl-L-carnitine improved pain and symptom scores after 60 days, but not hand function.
53.SupplementDEX Database: Carpal tunnel syndrome — Acetyl-L-carnitine to enhance nerve regeneration in carpal tunnel syndrome: a double-blind, randomized, controlled trial2019
A 2-month RCT in 20 women with severe carpal tunnel syndrome post-surgery found acetyl-L-carnitine 3000 mg/day did not improve nerve regeneration or functional outcomes versus placebo.
SupplementDEX Database · Chronic fatigue syndrome
1 reference54.SupplementDEX Database: Chronic fatigue syndrome — Exploratory open-label, randomized study of acetyl- and propionylcarnitine in chronic fatigue syndrome2004
An open RCT in 90 chronic fatigue syndrome patients found acetyl-L-carnitine 2 g/day for 24 weeks improved mental fatigue and propionyl-L-carnitine improved general fatigue; combined treatment was less effective.
SupplementDEX Database · Diabetes
1 reference55.SupplementDEX Database: Diabetes — Blood pressure and metabolic effects of acetyl-L-carnitine in type 2 diabetes: DIABASI randomized controlled trial2018
The DIABASI RCT in 229 hypertensive type 2 diabetes patients found acetyl-L-carnitine 1000 mg twice daily for 6 months did not improve blood pressure, glycemic control, lipids, or insulin sensitivity versus placebo on statin therapy.
SupplementDEX Database · Fibromyalgia
3 references56.SupplementDEX Database: Fibromyalgia — Palmitoylethanolamide and acetyl-L-carnitine act synergistically with duloxetine and pregabalin in fibromyalgia: results of a randomized controlled study2023
An RCT in 130 fibromyalgia patients on duloxetine plus pregabalin found adding palmitoylethanolamide 600 mg and acetyl-L-carnitine 500 mg twice daily for 12 weeks further reduced pain and disease severity scores.
57.SupplementDEX Database: Fibromyalgia — A randomized controlled trial comparing duloxetine and acetyl-L-carnitine in fibromyalgic patients: preliminary data2015
A preliminary RCT in 65 women with fibromyalgia found acetyl-L-carnitine 1500 mg/day and duloxetine 60 mg/day both improved pain and depression over 12 weeks; duloxetine improved psychological quality of life more.
58.SupplementDEX Database: Fibromyalgia — Double-blind, multicenter trial comparing acetyl-L-carnitine with placebo in the treatment of fibromyalgia patients2007
A multicenter RCT in 102 fibromyalgia patients found acetyl-L-carnitine (oral plus IM for 2 weeks, then oral for 8 weeks) continued to improve tender points and pain scores at 10 weeks versus placebo.
SupplementDEX Database · Fragile X syndrome
2 references59.SupplementDEX Database: Fragile X syndrome — A double-blind, parallel, multicenter comparison of L-acetylcarnitine with placebo on attention deficit hyperactivity disorder in Fragile X syndrome boys2008
A 1-year multicenter RCT in 56 boys with fragile X syndrome and ADHD found L-acetylcarnitine (20–50 mg/kg/day) reduced hyperactivity and improved social behavior versus placebo on Conners' and Vineland scales.
60.SupplementDEX Database: Fragile X syndrome — Double-blind, placebo-controlled study of L-acetylcarnitine for the treatment of hyperactive behavior in Fragile X syndrome1999
A double-blind, placebo-controlled study examined L-acetylcarnitine for hyperactive behavior in fragile X syndrome; insufficient abstract detail is available to report specific outcomes.
SupplementDEX Database · Frailty
1 reference61.SupplementDEX Database: Frailty — Acetyl-L-carnitine slows the progression from prefrailty to frailty in older subjects: a randomized interventional clinical trial2022
An RCT in 92 prefrail older adults found acetyl-L-carnitine 3 g/day for 3 months improved MMSE scores and 6-minute walk distance and reduced CRP versus placebo.
SupplementDEX Database · Hepatic encephalopathy
5 references62.SupplementDEX Database: Hepatic encephalopathy — Acetyl-L-carnitine for patients with hepatic encephalopathy2019
A Cochrane review of 5 RCTs (398 patients) found insufficient evidence that acetyl-L-carnitine improves quality of life or fatigue in hepatic encephalopathy; all trials were at high risk of bias.
63.SupplementDEX Database: Hepatic encephalopathy — Oral acetyl-L-carnitine treatment in hepatic encephalopathy: view of evidence-based medicine2013
A meta-analysis of 7 RCTs (660 patients) with hepatic encephalopathy found acetyl-L-carnitine improved serum ammonia and number connection test completion time versus placebo.
64.SupplementDEX Database: Hepatic encephalopathy — Acetyl-L-carnitine reduces depression and improves quality of life in patients with minimal hepatic encephalopathy2011
An RCT in 67 patients with minimal hepatic encephalopathy found acetyl-L-carnitine 4 g/day for 90 days improved quality of life, depression scores, and ammonia levels versus placebo.
65.SupplementDEX Database: Hepatic encephalopathy — Oral acetyl-L-carnitine therapy reduces fatigue in overt hepatic encephalopathy: a randomized, double-blind, placebo-controlled study2011
An RCT in 121 patients with overt hepatic encephalopathy found acetyl-L-carnitine 2 g twice daily for 90 days reduced fatigue severity and increased physical activity versus placebo.
66.SupplementDEX Database: Hepatic encephalopathy — Acetyl-L-carnitine improves cognitive functions in severe hepatic encephalopathy: a randomized and controlled clinical trial2011
An RCT in 61 patients with severe hepatic encephalopathy found acetyl-L-carnitine 2 g twice daily for 90 days improved cognitive test scores and reduced ammonia versus placebo.
SupplementDEX Database · Multiple sclerosis
1 reference67.SupplementDEX Database: Multiple sclerosis — Evaluating the effects of amantadine, modafinil and acetyl-L-carnitine on fatigue in multiple sclerosis: results of a pilot randomized, blind study2013
A pilot RCT in 60 MS patients found 1 month of amantadine 200 mg/day significantly reduced fatigue versus placebo; acetyl-L-carnitine 2 g/day showed only a trend toward benefit.
SupplementDEX Database · Peyronie's disease
1 reference68.SupplementDEX Database: Peyronie's disease — Acetyl-L-carnitine vs tamoxifen in the oral therapy of Peyronie's disease: a preliminary report2001
An RCT in 48 Peyronie's disease patients found acetyl-L-carnitine 1 g twice daily for 3 months reduced pain and disease progression more than tamoxifen 20 mg twice daily, with fewer side effects.
SupplementDEX Database · PCOS
2 references69.SupplementDEX Database: PCOS — Acetyl-L-carnitine ameliorates metabolic and endocrine alterations in women with PCOS: a double-blind randomized clinical trial2021
An RCT in 147 women with PCOS found adding acetyl-L-carnitine to metformin plus pioglitazone for 12 weeks improved insulin, adiponectin, body circumference, and restored regular menses in 97% versus 13% on metformin alone.
89.Clinical evidence of the effects of carnitine supplementation on body weight, glycemic control and serum lipids in women with polycystic ovary syndrome: a systematic review and meta-analysisExternal source
SupplementDEX Database · Schizophrenia
1 reference70.SupplementDEX Database: Schizophrenia — Acetyl-L-carnitine augmentation of clozapine in partial-responder schizophrenia: a 12-week, open-label uncontrolled preliminary study2016
A 12-week open-label trial in 9 schizophrenia patients on clozapine found acetyl-L-carnitine 1 g/day add-on reduced positive symptoms modestly but did not meaningfully improve overall PANSS scores.
SupplementDEX Database · Sciatica
1 reference71.SupplementDEX Database: Sciatica — Thioctic acid and acetyl-L-carnitine in the treatment of sciatic pain caused by a herniated disc: a randomized, double-blind, comparative study2008
An RCT in 64 sciatica patients found thioctic acid 600 mg/day produced greater symptom score improvements and reduced analgesic need more than acetyl-L-carnitine 1180 mg/day after 60 days.
SupplementDEX Database · Stroke
1 reference72.SupplementDEX Database: Stroke — Clinical evidence of acetyl-L-carnitine efficacy in the treatment of acute ischemic stroke: a pilot clinical trial2022
A pilot RCT in 69 acute ischemic stroke patients found acetyl-L-carnitine 1000 mg three times daily for 3 days improved NIHSS and mRS at 90 days, with 52.9% achieving mRS 0–1 versus 28.6% on placebo.
Safety (2000 mg long term)
1 reference73.Risk assessment for carnitineExternal source
Safety (8 weeks; 12 months)
1 reference74.A prospective study to evaluate the efficacy and safety of oral acetyl-L-carnitine for the treatment of chemotherapy-induced peripheral neuropathyExternal source
bioavailability
1 reference75.Kinetics, pharmacokinetics, and regulation of L-carnitine and acetyl-L-carnitine metabolismExternal source
Daily Value / western diet
1 reference76.Carnitine — Health Professional Fact Sheet. NIH Office of Dietary Supplements. ODSExternal source
carnitine food list
1 reference77.Characteristics of Selected Antioxidative and Bioactive Compounds in Meat and Animal Origin Products. PMC6769838. PMCExternal source
How does carnitine work?
1 reference78.Carnitine transport and fatty acid oxidationExternal source
facilitate, stabilisation, exercise
1 reference79.The Role of l-Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease InitiationExternal source
transport system
1 reference80.The Carnitine Palmitoyl Transferase (CPT) System and Possible Relevance for Neuropsychiatric and Neurological ConditionsExternal source
ketogenesis
1 reference81.Mitochondrial Fatty Acid Oxidation Disorders: Laboratory Diagnosis, Pathogenesis, and the Complicated Route to TreatmentExternal source
Who has risk? (pregnant)
1 reference82.Carnitine Deficiency — StatPearls — NCBI Bookshelf. NCBI BooksExternal source
When necessary? (children)
1 reference83.Carnitine deficiency disorders in childrenExternal source
premature infants
1 reference84.Carnitine Inborn Errors of MetabolismExternal source
markers
1 reference85.Carnitine supplementation of parenterally fed neonatesExternal source
kidney disease
1 reference86.Effects of L-carnitine supplementation in maintenance hemodialysis patients: a systematic reviewExternal source
vegetarians/vegans
1 reference87.Effect of L-carnitine supplementation on the body carnitine pool, skeletal muscle energy metabolism and physical performance in male vegetariansExternal source
sleep/narcolepsy
1 reference88.Impact of L-carnitine in narcolepsy treatment: a systematic review on the effectiveness and safetyExternal source
PCOS glucose/insulin
1 reference90.Effects of L-carnitine on Polycystic Ovary SyndromeExternal source