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1. Charles Patrick Davis, MD, PhD (8/29/2018). “ACETYL-L-CARNITINE”. Retrieved from https://www.rxlist.com/acetyl-l-carnitine/supplements.htm.

 

INTRODUCTION

 

In the body, Acetyl-L-Carnitine is made from L-Carnitine. It can also be converted to L-Carnitine. L-Carnitine is an amino acid (a building block for proteins) that is naturally produced in the body. It helps produce energy. Although it is an amino acid, L-Carnitine is not used to make proteins.

 

Acetyl-L-Carnitine is used for a variety of mental disorders including Alzheimer’s disease, age-related memory loss, late-life depression, thinking problems related to alcoholism, thinking problems related to Lyme disease, and thinking problems related to very poor liver function (hepatic encephalopathy). It is also used for withdrawal from alcohol, Down syndrome, bipolar disorder, poor circulation in the brain after a stroke, cataracts, nerve pain due to diabetes, nerve pain due to drugs used in the treatment of AIDS or cancer, nerve pain caused by sciatica, fibromyalgia, and facial paralysis. Acetyl-L-Carnitine is used for tiredness related to getting older, tiredness related to a disease called multiple sclerosis, a muscle wasting disease called amyotrophic lateral sclerosis, high levels of activity in children with the genetic condition fragile-X syndrome, and attention deficit-hyperactivity disorder (ADHD). It is also used for aging skin.

 

Some men use acetyl-L-Carnitine for infertility, symptoms of “male menopause” (low testosterone levels due to aging), and a disease of the penis called Peyronie’s disease.

 

The body can convert L-Carnitine to acetyl-L-Carnitine and vice versa. But, no one knows whether the effects of acetyl-L-Carnitine are from the chemical itself, from the L-Carnitine it can make, or from some other chemical made along the way. For now, don’t substitute one form of Carnitine for another.

 

ACETYL – L – CARNITINE BENEFITS (Aleksa Ristic, MS (Pharmacy), reviewed by Ana Aleksic, MSc (Pharmacy), last updated: November 5, 2019. “9 Acetyl-L-Carnitine Benefits + Dosage & Side Effects”. Retrieved from https://selfhacked.com/blog/acetyl-l-carnitine/)

 

Possibly Effective:

 

— Nerve Damage

 

Nerves are particularly sensitive to oxidative stress. Certain drugs and conditions such as diabetes can cause nerve damage (neuropathy), which manifests with pain, tingling, or numbness in legs and arms.

 

In two meta-analyses with more than 2,000 neuropathy patients, Acetyl-L-Carnitine (ALCAR) significantly reduced pain and improved nerve health.

 

— Diabetic Neuropathy

 

Acetyl-L-Carnitine seems to be an effective option for diabetic neuropathy. A review of six clinical trials (711 patients) suggested its ability to shield the nerves against toxic glucose levels and reduce pain in people with diabetes. However, the results are less convincing when it comes to nerve conduction speed.

 

— Anti-HIV Treatment

 

Anti-HIV drugs can also cause nerve damage, antiretroviral toxic neuropathy (ATN), which is a major drawback of HIV treatment. Based on multiple reviews and clinical trials, ALCAR (2-3 g daily) can repair nerve damage and relieve pain and other symptoms in patients with ATN [21, 22, 23, 24].

 

— Other

 

According to animal trials and limited clinical evidence, Acetyl-L-Carnitine may also help with:

 

– Carpal tunnel syndrome (hand and wrist nerve injury)
– Spinal cord injury
– Chronic pain due to nerve damage and inflammation
– On the other hand, it may not help with nerve damage from chemotherapy (more details below).

 

A limitation for neuropathy benefits is that many studies used intravenous or intramuscular treatment; oral supplementation might not have the same effects.

 

Acetyl-L-Carnitine can repair nerve damage and relieve pain caused by diabetes, anti-HIV treatment, and injuries. These conditions may require intravenous or intramuscular treatment.

 

— Depression

 

Acetyl-L-Carnitine (ALCAR) supplies the nerves with energy and enables the production of neurotransmitters crucial for mental health; these include Acetylcholine, GABA, and Glutamate.

 

It strengthens the myelin around the brain cells and stimulates their growth, helping to “regrow” your brain.

 

According to a meta-analysis of 11 clinical trials (791 patients), ALCAR is superior to placebo in reducing depressive symptoms. It seems to have effects comparable to standard antidepressants while causing fewer side effects.

 

Two clinical reviews came to a similar conclusion but also pointed out certain limitations that call for further research. According to one review, ALCAR is especially suitable for older patients and those struggling with side effects from antidepressants.

 

Rapid onset of action is another advantage of ALCAR when it comes to depression. Although patients used it for two months or more, most of them experienced improvement after one week.

 

Acetyl-L-Carnitine may reduce depression by protecting the nerves and boosting neurotransmitters. In some studies, it had fewer side effects and acted faster than standard antidepressants.

 

— Alzheimer’s Disease

 

No other neurotransmitter is more important for cognition and memory than acetylcholine; impaired cholinergic transmission is the hallmark of Alzheimer’s disease.

 

By boosting cholinergic activity in the brain, ALCAR may help prevent cognitive decline and Alzheimer’s disease.

 

It also increases brain levels of glutathione, shielding it against oxidative stress and amyloid beta plaques that destroy neurons in Alzheimer’s disease.

 

A meta-analysis summarized the data from 21 clinical trials with more than 1,200 Alzheimer’s disease patients. Long-term treatment with acetyl-L-carnitine (1.5-3g daily for 3+ months) was safe and significantly improved the patients’ mental condition.

 

Alzheimer’s patients receiving ALCAR had improved:

– Attention and memory
– Mental agility and focus (reaction time)
– Speech and behavior

 

Another large review by came to a similar conclusion, though the authors emphasized most improvements were subjective. They also pointed to other statistical limitations and concluded that more research is needed to confirm the clinical effectiveness of ALCAR [40].

 

According to a study of 23 patients with drug-resistant Alzheimer’s disease, acetyl-carnitine may boost the effectiveness of standard drugs, such as donepezil (Aricept) and rivastigmine (Exelon).

 

Acetyl-L-carnitine may help with Alzheimer’s disease by boosting acetylcholine and reducing oxidative stress in the brain. It may also improve the effectiveness of drug treatment.

 

— Fertility and Sexual Function

 

Men

 

In a meta-analysis of nine clinical trials with over 800 infertile men, a combination of L-Carnitine and ALCAR significantly improved sperm mobility. As a result, the chance of a successful pregnancy increased more than 4 times.

 

In 120 older patients, a combination of Acetyl-L-Carnitine and Propionyl-Carnitine (2 g daily each, for 6 months) was as effective as testosterone in improving sexual dysfunction. Carnitines showed even better effects on erectile function and, unlike testosterone, didn’t cause prostate enlargement.

 

Peyronie’s disease manifests with a curved penis during erection, due to the presence of scar tissue or plaque, which may lead to erectile dysfunction. In a study of 48 patients with this condition, ALCAR showed better results than a drug, tamoxifen. Unlike tamoxifen, ALCAR significantly reduced penile curvature while having fewer side effects.

 

Women

 

Women with hypothalamic amenorrhea have irregular cycles and fertility issues due to inadequate GnRH secretion. ALCAR increased sex hormones and improved the symptoms in three studies of 71 women.

 

Acetyl-L-Carnitine may improve fertility and sexual function in both sexes, but the evidence for women is weaker. A combination with L-Carnitine has shown the best results.

 

— Cognitive Decline and Brain Damage

 

The brain-protective effects of Acetyl-L-Carnitine aren’t limited to Alzheimer’s disease. It may also improve memory and reduce mental fatigue from different causes.

 

Studies in Older People

 

Maintaining good brain health is especially important for the ageing brain. As cells age, they become senescent: less functional and more pro-inflammatory. As a result, they produce less Acetylcholine.

 

Research suggests that ALCAR might offset senescence and thus improve mental health and cognition in the elderly.

 

In two studies with 576 older people, Acetyl-L-Carnitine enhanced cognition, improved mood and behavior, and reduced fatigue. In 56 older patients, it partially reversed dementia due to reduced blood flow in the brain.

 

Animal Studies

 

Many animal trials suggest that ALC may support learning, memory, and emotional health. Scientists observed its ability to shield the brain and improve cognition by:

 

– Maximizing energy (ATP) production
– Boosting mitochondrial health
– Increasing acetylcholine
– Scavenging free radicals
– Preventing brain aging caused by lactate buildup in the brain

 

Based on these effects, Acetyl-L-Carnitine might also have nootropic effects (improve cognition) regardless of age, though studies haven’t researched this yet.

 

Alpha-Lipoic Acid Synergy
Alpha-lipoic acid is another potent antioxidant that protects the nerves against diabetes and other conditions with increased oxidative stress.

 

According to animal studies and limited clinical data, acetyl-L-carnitine and alpha-lipoic acid may have a synergistic effect on brain aging and oxidative damage, which makes them a potential combination for cognitive support [63, 64, 65, 66].

 

Well-designed clinical trials should test the safety and efficacy of this combination.

 

Acetyl-L-Carnitine combats brain ageing and improves cognition, mood, and energy. A combination with alpha-lipoic acid may yield even better results, but the evidence is limited.

 

— Hepatic Encephalopathy

 

Acetyl-L-Carnitine was effective for brain damage due to liver disease (hepatic encephalopathy) in three clinical trials of over 250 patients. The treatment with ALCAR:

 

– Reduced depression and improved cognitive function
– Enhanced social function and general wellbeing
– Lowered the levels of ammonia and improved other biomarkers

 

— Fatigue

 

In 96 older people, supplementation with Acetyl-L-Carnitine improved:

 

– Fatigue after exercise, by 51%
– Muscle pain, by 27%
– Sleep disorders, by 28%
– It also boosted mood and mental clarity while causing no side effects.

 

ALCAR (2g daily) significantly improved mental fatigue and attention in 30 patients with chronic fatigue syndrome.

 

Patients with chronic fatigue due to multiple sclerosis may also benefit from Acetyl-L-Carnitine, but the available research doesn’t allow for a definite conclusion.

 

ALCAR may boost energy production and combat fatigue. It’s particularly effective in older people who often lack Carnitine.

 

— Fibromyalgia Symptoms

 

Fibromyalgia is a complex syndrome that manifests with muscle pain, fatigue, and mood problems. Doctors are still looking for effective treatment options.

 

Acetyl-L-Carnitine significantly reduced pain and depressive symptoms in 102 fibromyalgia patients. Researchers used a combination of oral (1000 mg/day) and intramuscular treatment.

 

In 65 women with fibromyalgia, ALCAR relieved pain and depression; it was equally effective as an antidepressant Duloxetine.

 

— Alcohol Addiction

 

In a study of 64 alcohol abusers, ALCAR (1g/day) provided some short-term benefits such as longer abstinence and reduced cravings. Further research should investigate the potential benefits for alcohol addiction and similar disorders in the long run.

 

— Weight Loss and Bodybuilding

 

Acetyl-L-Carnitine is a popular supplement for boosting weight loss and physical performance, especially among bodybuilders. Most studies in this field have tested L-Carnitine, and they showed mixed results.

 

A meta-analysis of nine clinical trials and 911 people suggested mild benefits of L-Carnitine for weight loss. However, the effect tended to diminish over time, so it might be a good strategy to use it over short cutting cycles.

 

According to limited clinical evidence and animal trials, supplementation with L-Carnitine may enhance physical performance, speed up recovery, and stimulate fat burning.

 

In theory, ALCAR might provide the same benefits by supplying L-Carnitine, but no studies have confirmed this.

 

— Diabetes and Heart Health

 

Impaired fatty acid metabolism and oxidative stress contribute to diabetes. ALCAR may help prevent diabetes or reduce the symptoms by enhancing the breakdown of fats and scavenging free radicals.

 

In a small trial of 18 diabetic patients, intravenous ALCAR treatment improved glucose control.

 

However, a study of 229 diabetics with high blood pressure and lipids found no effects of ALCAR supplementation on glucose metabolism, lipid levels, or blood pressure.

 

SIDE EFFECTS AND PRECAUTIONS

 

Side Effects

 

Acetyl-L-Carnitine was safe and well-tolerated in most clinical trials. In rare cases, it caused:

 

– Upset stomach
– Vomiting
– Diarrhoea
– Headache
– Insomnia

 

Our bodies partly metabolize Carnitine into Trimethylamine-N-oxide (TMAO), which may promote plaque build-up in blood vessels (atherosclerosis). In a study of over 2,500 people, those with higher blood levels of L-Carnitine had increased rates of heart disease [92].

 

There are various ways to lower your TMAO levels, such as eating more vegetables, dietary fiber, probiotic– and resveratrol-rich foods.

 

L-Carnitine supplementation may cause unpleasant fishy odour and suppress thyroid hormones. ALCAR might do the same, but studies haven’t confirmed this.

 

Acetyl-L-Carnitine is likely safe for long-term use. It might contribute to heart disease and suppress thyroid hormones, but more research is needed to confirm this.

 

Sensitive Groups

 

Safety data about acetyl-L-Carnitine during pregnancy is lacking, while the evidence for L-Carnitine is limited. If you’re pregnant or trying to conceive, stay on the safe side and avoid ALCAR supplements.

 

RESEARCH DOSAGE

 

Although meat and animal products are the main dietary source of Carnitine, most ALCAR supplements are vegan-friendly.

 

The below doses used in clinical trials may not apply to you personally. If your doctor suggests using ALCAR, work with them to find the optimal dosage according to your health condition and other factors.

 

The effective dosage of Acetyl-L-Carnitine for most conditions ranges from 1500 to 3000 mg, divided into two or three daily doses. Standard treatment duration is 2-3 months, though cognitive impairment and nerve damage may require 6-12 months.

 

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