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Alc9.0
Acetyl-L-Carnitine Research
Likely helpsHigh safety
32 peer-reviewed studies
What the evidence says
Likely helps
Acetyl-L-Carnitine appears to help in 8 of 11 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 2003–2025 with a typical study size of 200 participants.
Based on 32 studies · 15 meta-analyses · 8 RCTs · 11,626 total participants
Confidence
High
What the studies found
8helped3unclear· 21 more without graded effect data
By outcome
Therapeutic & clinical
Mixed evidence15 studies
Cognitive functionBetter memory, especially in older adults · 4-12 weeks
Depression & moodAntidepressant effects comparable to some medications in meta-analyses · 4-8 weeks
Mostly mechanism / observational3 studies
Fertility & reproductiveMay support reproductive health and fertility markers · 4-12 weeks
Mostly mechanism / observational3 studies
Energy & fatigueEnhanced mental and physical energy · 1-2 weeks
Too few graded studies2 studies
By the numbers
Pulled from 30 studies with measurable effects
Likely real effects
100%
across studies
People studied
12k
typical study: 200 people
Strongest designs
23
15 pooled, 8 randomised
Showed benefit
73%
8/11 studies
How long studies ran
1–3 months
2
3+ months
2
Populations Studied
Hepatic encephalopathy patients2
Multiple sclerosis patients2
Major depressive disorder patients2
Fibromyalgia patients2
Active research area
14 studies in the last 5 years · Latest meta-analysis: 2025
200320142025
1Erectile function improvementMeta-AnalysisCited 4×n=1,000 · large study2024
Against a background of general ineffectiveness of most nutraceutical interventions, L-Arginine and the mix PLC + ALC appeared to be of some usefulness in improving erectile function, especially in combination with PDE5i in organic ED.
Barbonetti A et al. · The journal of sexual medicine (2024)
In patients with organic ED, the efficacy of Sildenafil and Tadalafil was significantly improved by PLC + ALC and L-Arginine, respectively.
Against a background of general ineffectiveness of most nutraceutical interventions, L-Arginine and the mix PLC + ALC appeared to be of some usefulness in improving erectile function, especially in combination with PDE5i in organic ED.
3Pain reduction in diabetic peripheral neuropathyMeta-AnalysisCited 45×n=907 · large study2019
We are very uncertain whether ALC causes a reduction in pain after 6 to 12 months' treatment in people with DPN, when compared with placebo, as the evidence is sparse and of low certainty.
Rolim LC et al. · The Cochrane database of systematic reviews (2019)
Noticeable benefit
← WorseNo effectBetter →
Likely real
The risk of bias was high in both trials of different ALC doses and low in the other two trials.No included trial measured the proportion of participants with at least moderate (30%) or substantial (50%) pain relief.
ALC reduced pain more than placebo, measured on a 0- to 100-mm VAS (MD -9.16, 95% CI -16.76 to -1.57; three studies; 540 participants; P = 0.02; I² = 56%; random-effects; very low-certainty evidence; a higher score indicating more pain).
The overall certainty of adverse event evidence for the comparison of ALC versus placebo was low.The study comparing ALC with methylcobalamin reported that 34/117 participants (29.1%) experienced adverse events in the ALC group versus 33/115 (28.7%) in the methylcobalamin group (P = 0.95).
5Sperm quality and pregnancy ratesMeta-AnalysisCited 1×2025
CoQ10 was the most effective intervention measure for improving sperm concentration, and L-carnitine was regarded as the best treatment method for enhancing sperm motility.
Niu C et al. · Reproductive sciences (Thousand Oaks, Calif.) (2025)
Huge benefit
← WorseNo effectBetter →
L-carnitine, coenzyme Q10 and L-carnitine + acetyl-L-carnitine significantly improved sperm quality parameters compared with placebo.
CoQ10 induced the highest increase in sperm concentration (SMD 2.98 [95% CI: 1.13 to 7.87]).
Furthermore, L-Carnitine has the greatest improvement effect on progressive sperm motility (SMD 4.19 [95% CI: 1.60 to 10.95]).
8Serum ammonia levelMeta-AnalysisCited 23×n=660 · large study2013
Acetyl-L-carnitine is promising as an effective and tolerable treatment for hepatic encephalopathy that associated with improved serum ammonia levels and the number connection test.
Jiang Q et al. · Annals of hepatology (2013)
Noticeable benefit
← WorseNo effectBetter →
Acetyl-L-carnitine was effective to improve serum ammonia level (weighted mean difference 25.90, 95% confidence intervals 20.89 to 30.91, P < 0.05) and the number connection test completion time (weighted mean difference 16.62, 95% confidence intervals 9.88 to 23.36, P < 0.05).
Acetyl-L-carnitine is promising as an effective and tolerable treatment for hepatic encephalopathy that associated with improved serum ammonia levels and the number connection test.
Duloxetine is an effective and well-tolerated option, while pregabalin shows promising results but requires further investigation.
Jesus Palma AC et al. · Pain management nursing : official journal of the American Society of Pain Management Nurses (2025)
Investigated medications exhibited varied outcomes, with some showing significant benefits in reducing neuropathic pain while others did not demonstrate statistically significant efficacy.
Duloxetine is an effective and well-tolerated option, while pregabalin shows promising results but requires further investigation.
Other agents, such as venlafaxine and tapentadol, lack strong supporting evidence.
11Global impression of deteriorationMeta-AnalysisCited 79×n=217 · medium study2020
There are a variety of controlled trials addressing the effects of dietary interventions for MS with substantial variation in active treatment, comparator, and outcomes of interest.
Parks NE et al. · The Cochrane database of systematic reviews (2020)
No clear effect
← WorseNo effectBetter →
Among four trials comparing PUFAs with MUFAs, there may be little to no difference in global impression of deterioration (RR 0.85, 95% CI 0.71 to 1.03; 4 studies, 542 participants; 40% in the PUFA group versus 47% in the MUFA group; low-certainty evidence).
In two trials comparing different PUFAs (omega-3 versus omega-6), there may be little to no difference in relapses (RR 1.02, 95% CI 0.62 to 1.66; 2 studies, 129 participants; 30% in the omega-3 versus 29% in the omega-6 group; low-certainty evidence).
Among three trials comparing omega-3 with omega-6, there may be little to no difference in change in disability progression, measured as mean change in Expanded Disability Status Scale (EDSS) (mean difference (MD) 0.00, 95% CI -0.30 to 0.30; 3 studies, 166 participants; low-certainty evidence).
12Blood ammonium levelsMeta-AnalysisCited 32×n=398 · medium study2019
This Cochrane systematic review analysed a heterogeneous group of five trials at high risk of bias and with high risk of random errors conducted by only one research team.
Martí-Carvajal AJ et al. · The Cochrane database of systematic reviews (2019)
Noticeable benefit
← WorseNo effectBetter →
The effects of acetyl-L-carnitine compared with placebo on general health at 90 days are uncertain (MD -6.20 points, 95% confidence interval (CI) -9.51 to -2.89).
Meta-analysis showed a reduction in blood ammonium levels favouring acetyl-L-carnitine versus placebo (MD -13.06 mg/dL, 95% CI -17.24 to -8.99; 387 participants; 5 trials; very low-quality evidence).
It is unclear whether acetyl-L-carnitine versus placebo increases the risk of non-serious adverse events (8/126 (6.34%) vs 3/120 (2.50%); RR 2.51, 95% CI 0.68 to 9.22; 2 trials; very low-quality evidence).
13Systematic ReviewCited 14×n=22 · very small study2024
Based on the review, we cannot recommend any supplement use for the management of CIPN, although further research into N-acetyl-cysteine, l-carnosine, crocin, and magnesium is warranted.
Frediani JK et al. · Pain practice : the official journal of World Institute of Pain (2024)
Based on the review, we cannot recommend any supplement use for the management of CIPN, although further research into N-acetyl-cysteine, l-carnosine, crocin, and magnesium is warranted.
Acetyl-l-carnitine was found to be likely ineffective or harmful.
14Peripheral blood metabolites in major depressive disorderMeta-AnalysisCited 171×n=46 · small study2021
This meta-analysis examined the effects of Acetyl-L-Carnitine.
Pu J et al. · Molecular psychiatry (2021)
Pathway and network analyses revealed altered amino acid metabolism and lipid metabolism, especially for the tryptophan-kynurenine pathway and fatty acid metabolism, in the peripheral system of MDD patients.
Our findings may facilitate biomarker development and the elucidation of the molecular mechanisms that underly MDD.
15Treatment recommendations for nutraceuticals and phytoceuticals in psychiatric disordersMeta-AnalysisCited 117×2022
Based on the current data and clinician input, a range of nutraceuticals and phytoceuticals were given either a supportive recommendation or a provisional recommendation across a range of various psychiatric disorders.
Sarris J et al. · The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry (2022)
Based on the current data and clinician input, a range of nutraceuticals and phytoceuticals were given either a supportive recommendation or a provisional recommendation across a range of various psychiatric disorders.
However several had only a weak endorsement for potential use; for a few it was not possible to reach a clear recommendation direction, largely due to mixed study findings; while some other agents showed no obvious therapeutic benefit and were clearly not recommended for use.
It is the intention of these guidelines to inform psychiatric/medical, and health professional practice globally.
16Pain improvement in fibromyalgiaSystematic ReviewCited 52×2020
Therefore, there is insufficient evidence to recommend any one particular nutritional intervention for the management of fibromyalgia and further research is needed.
Lowry E et al. · Nutrients (2020)
It is estimated to have a worldwide prevalence of 1.78%, with a predominance in females.
Significant improvements in reported pain were observed for those following a vegan diet, as well as with the low fermentable oligo di-mono-saccharides and polyols (FODMAP) diets.
Supplementation with Chlorella green algae, coenzyme Q10, acetyl-l-carnitine or a combination of vitamin C and E significantly improved measures of pain.
There is insufficient evidence that carnitine for the treatment of MS-related fatigue offers a therapeutic advantage over placebo or active comparators.
Tejani AM et al. · The Cochrane database of systematic reviews (2012)
No clear effect
← WorseNo effectBetter →
There was no difference between carnitine and amantadine for the number of patients withdrawing from the study due to an adverse event (relative risk ratio 0.20; 95% confidence interval 0.03 to 1.55) and no patients experienced a serious adverse event in either treatment group.
There is insufficient evidence that carnitine for the treatment of MS-related fatigue offers a therapeutic advantage over placebo or active comparators.
Results of the ongoing trial are eagerly anticipated in order to provide clarity.
20Glaucoma biomarker identificationSystematic ReviewCited 43×n=13 · very small study2021
In this review, we summarize existing metabolomic studies related to glaucoma biomarker identification and point out a series of metabolic disorders in OAG patients, providing information on the molecular mechanism changes in glaucoma.
Wang Y et al. · Investigative ophthalmology & visual science (2021)
In this review, we summarize existing metabolomic studies related to glaucoma biomarker identification and point out a series of metabolic disorders in OAG patients, providing information on the molecular mechanism changes in glaucoma.
Additional studies are needed to validate existing findings, and future research will need to explore the potential overlap between different biological fluids.