Acetyl-L-carnitine: benefits, dosage, contraindications
Scientific name(s)
Acetyl-L-carnitine
Family or group:
Pseudovitamin s
Indications
Scoring methodology
EFSA approval.
Cognitive decline ✪✪✪✪✪
Acetyl-L-carnitine appears to improve cognitive function and memory in elderly people with age-related cognitive impairment.
Posologie
Oral
1.5 - 2 g
3 - months
Seniors
Depression ✪✪✪✪✪
An analysis of clinical research conducted in Europe shows that acetyl-L-carnitine (1 to 4 grams per day) moderately reduces depressive symptoms compared with placebo in patients with dysthymia and depression. Acetyl-L-carnitine appears to be more effective in older patients and when used at higher doses.
Posologie
Oral
1 - 4 g
60 - days
Seniors
L-acetylcarnitine in depressed elderly subjects. A cross-over study vs placebo.
Effect of acetyl-L-carnitine on geriatric patients suffering from dysthymic disorders.
Evaluation of the effects of L-acetylcarnitine on senile patients suffering from depression.
Acetyl-L-carnitine and alpha-lipoic acid: possible neurotherapeutic agents for mood disorders?
Diabetic neuropathy ✪✪✪✪✪
Acetyl-L-carnitine slows neuronal degeneration and promotes the repair of neurons damaged by type 1 and type 2 diabetes.nn
Posologie
Orally
1.5 - 3 g
Adults
Acetyl-L-carnitine improves pain, nerve regeneration, and vibratory perception in patients with chronic diabetic neuropathy: an analysis of two randomized placebo-controlled trials.
Acetyl-L-carnitine as a new therapeutic approach for painful peripheral neuropathies.
Effects of acetyl-L-carnitine and methylcobalamin for diabetic peripheral neuropathy: A multicenter, randomized, double-blind, controlled trial.
Fatigue ✪✪✪✪✪
Clinical studies have shown that taking acetyl-L-carnitine at a dose of 2 grams twice daily for 180 days reduced physical fatigue by 52% and mental fatigue by 43%, compared with only 4% and 8% respectively in elderly patients treated with placebo. Post-exercise fatigue was also reduced by 51% in elderly patients treated with acetyl-L-carnitine, compared with only 4% for placebo.nn
Posologie
Orally
2 - 2 g
180 days
Seniors
L-Carnitine treatment reduces severity of physical and mental fatigue and increases cognitive functions in centenarians: a randomized and controlled clinical trial.
Effects of Citric Acid and L-Carnitine on Physical Fatigue.
Acetyl-L-carnitine (ALC) treatment in elderly patients with fatigue.
Male fertility disorders ✪✪✪✪✪
The oral intake of 1 g of acetyl-L-carnitine, in combination with 2 g of L-carnitine for 3 to 6 months, appears to increase sperm motility in men with infertility. In addition, the oral intake of 500 mg of acetyl-L-carnitine, combined with 1 mg of L-carnitine every 12 hours after 2 months of treatment with nonsteroidal anti-inflammatory drugs, appears to increase sperm count and motility in men suffering from infertility due to abacterial prostatovesiculoepididymitis (an inflammation of the prostate, seminal vesicles, and epididymis).
Posologie
Oral administration
500 - 500 mg
6 - months
Men, Seniors
A placebo-controlled double-blind randomized trial of the use of combined l-carnitine and l-acetyl-carnitine treatment in men with asthenozoospermia.
[Clinical efficacy of combined L-carnitine and acetyl-L-carnitine on idiopathic asthenospermia].
Cinnoxicam and L-carnitine/acetyl-L-carnitine treatment for idiopathic and varicocele-associated oligoasthenospermia.
Alzheimer's disease ✪✪✪✪✪
Acetyl-L-carnitine may slow the progression of Alzheimer's disease and improve memory, cognitive, and behavioral functions. Its effect appears to be greater in patients younger than 66 years at the onset of the disease.
Posologie
Oral administration
1.5 - 3 g
3 - months
Seniors
Acetyl L-carnitine slows decline in younger patients with Alzheimer's disease: a reanalysis of a double-blind, placebo-controlled study using the trilinear approach.
Long-term acetyl-L-carnitine treatment in Alzheimer's disease.
Clinical and neurochemical effects of acetyl-L-carnitine in Alzheimer's disease.
Double-blind, placebo controlled study of acetyl-l-carnitine in patients with Alzheimer's dementia.
Double-blind parallel design pilot study of acetyl levocarnitine in patients with Alzheimer's disease.
Hepatic encephalopathy ✪✪✪✪✪
Some clinical research has shown that taking acetyl-L-carnitine at a dose of 2 grams twice a day for 90 days reduces mental and physical fatigue and improves some markers of liver function, compared with placebo, in patients with mild to severe hepatic encephalopathy. However, other clinical studies have shown that taking the same dose of acetyl-L-carnitine improves physical function, but not mental function, compared with placebo in patients with mild hepatic encephalopathy.
Posologie
Oral
2 - 2 g
90 - days
Adults
Acetyl-L-carnitine improves cognitive functions in severe hepatic encephalopathy: a randomized and controlled clinical trial.
Acetyl-L-carnitine reduces depression and improves quality of life in patients with minimal hepatic encephalopathy.
Alcoholism ✪✪✪✪✪
Clinical research has shown that acetyl-L-carnitine, administered at a dose of 1 to 3 grams per day by slow intravenous infusion over 3 to 4 hours for 10 days, followed by 3 grams per day orally for an additional 80 days, reduces smoking cravings, the inability to feel pleasure (anhedonia), melancholic symptoms, and lengthens the time to the first drink, compared with placebo, in alcoholic subjects undergoing withdrawal. In addition, taking this same dose reduces relapse rates compared with placebo.
Posologie
Oral
1 - 3 g
80 days
Alcohol-dependent subjects
Properties
Neurological
It has been demonstrated in animal models that acetyl-L-carnitine increases dopamine levels in specific parts of the brain and may modulate NMDA receptors (N-methyl-D-aspartate is an amino acid that, at the level of its receptors, mimics the action of a neurotransmitter: glutamate). This effect is used to reduce alcohol withdrawal symptoms. Indeed, it is thought that dopaminergic agents and antagonists of N-methyl-D-aspartate (NMDA) neurotransmission may play an important role in alcohol withdrawal. Furthermore, in humans, acetyl-L-carnitine increases beta-endorphin levels (hormones that act on pain and anxiety and produce relaxation), which may also facilitate alcohol withdrawal.
Usages associés
Bioenergetic
Acetyl-L-carnitine plays an important role in burning fat to produce energy, and in transporting fatty acids across the mitochondrial membranes (a cellular organelle), where they are oxidized and converted into energy.nn
Usages associés
Fertility effect
Acetyl-L-carnitine and L-carnitine are present in human semen and seminal fluid. Levels of acetyl-L-carnitine and the ratio between acetyl-L-carnitine and L-carnitine are lower in infertile semen samples and in low-motility sperm. An increase in sperm motility is observed in vitro when acetyl-L-carnitine or L-carnitine is added to the sample.nnPreliminary research also suggests that acetyl-L-carnitine may increase testosterone production and improve testicular function.nn
Usages associés
Cognitive function
Acetyl-L-carnitine plays a role in improving age-related conditions such as fatigue, cognitive impairments, and Alzheimer's disease, but it is not clear whether acetyl-L-carnitine improves cognition by stimulating mitochondrial activity in the brain or by making more acetyl groups available for use in the synthesis of acetylcholine (a neurotransmitter in the brain that is reduced in many forms of dementia).nn
Usages associés
Hypoglycemic
The role of carnitine in fat metabolism affects all other cellular energy metabolism, including carbohydrate oxidation. Thus it may be linked to glucose metabolism, insulin, and metabolic syndrome (it increases insulin sensitivity).nn
Hepatoprotective
In patients with alcohol-induced cirrhosis, serum levels of L-carnitine are sometimes increased, probably due to increased biosynthesis of L-carnitine. In subjects with hepatitis or cirrhosis complicated by hepatic encephalopathy (brain damage in the case of severe liver failure), acetyl-L-carnitine appears to improve liver enzyme levels, ammonia, urea, prothrombin and bilirubin.
Usages associés
Safe dosage
Adults aged 18 and older: 500 mg - 2000 mg
Acetyl-L-carnitine has been used safely for periods of up to 33 months orally. The doses used can range from 500 mg to 2000 mg per day.
Interactions
Médicaments
Antiplatelet agents/Anticoagulants: strong interaction
Taking 1 g per day of L-carnitine appears to significantly increase the anticoagulant effects of acenocoumarol (sintrom*). An increase in INR after taking L-carnitine has been observed. This increase persisted for 10 weeks until L-carnitine was stopped, at which point the INR normalized. This interaction has been reported only with L-carnitine, but theoretically it may occur with acetyl-L-carnitine. The implicated anticoagulants are: acenocoumarol (sintrom*), warfarin (coumadin*).
Antibiotics: moderate interaction
Cefditoren pivoxil (spectracef*), pivampicillin and pivmecillinam increase urinary excretion of carnitine. Theoretically, losses of acetyl-L-carnitine may also be increased. With short-term treatment, blood carnitine levels decrease, but tissue levels do not appear to be affected. Treatment for 1 to 2 months leads to a decrease in muscle carnitine, and treatment for 6 months or longer produces symptoms of carnitine deficiency. Routine supplementation with L-carnitine or acetyl-L-carnitine is not necessary unless the treatment is prolonged or the patient has other factors contributing to decreased carnitine stores.
Valproic acid: moderate interaction
Valproic acid interferes with the biosynthesis of L-carnitine in the liver and forms a valproylcarnitine ester that is excreted in the urine, which reduces the reabsorption of free carnitine. The decrease in L-carnitine is not clinically significant in people taking valproic acid. Risk factors for symptomatic L-carnitine deficiency with valproic acid are: - age under 2 years, - a severe neurological disorder, - use of antiepileptic drugs, - a ketogenic diet. Some experts recommend L-carnitine supplementation for people treated with valproic acid who have the above risk factors.
Precautions
Pregnancy: avoid
Avoid use due to lack of reliable and sufficient information.
Hypothyroidism: avoid
L-carnitine appears to inhibit the activity of thyroid hormones at the level of target tissues. Theoretically, this could occur with acetyl-L-carnitine.
Bipolar disorder: avoid
Acetyl-L-carnitine may increase the risk of mania in patients with bipolar disorder.
Epilepsy: avoid
An increase in the frequency or severity of seizures has been reported in patients who have previously used L-carnitine orally or intravenously. Theoretically, this could occur with acetyl-L-carnitine.
Chemotherapy: avoid
The use of acetyl-L-carnitine in patients receiving taxane-based chemotherapy may increase symptoms of chemotherapy-induced neuropathy. nn
Breastfeeding woman: avoid
Avoid use due to lack of reliable and sufficient information.nn
