9 Amazing Acetyl-L-Carnitine Benefits & Side Effects

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Acetyl-L-carnitine can lift your mood, sharpen your mind, and offset brain aging. It works by maximizing energy use in the body and boosting acetylcholine, the most important neurotransmitter for learning and memory. Read on to find out if acetyl-L-carnitine is for you and how to use it for optimal results.

Acetyl-L-carnitine (ALC or ALCAR) is an amino acid that fuels energy production in your cells and supports nerve function. It supplies the acetyl group for burning fats in your mitochondria (fatty acid oxidation) and producing acetylcholine [1, 2].

Your muscles and heart tissue stock different forms of carnitine as energy reserves [3].

Meat and other animal foods contain L-carnitine, but your liver and kidneys can also produce it from two amino acids: lysine and methionine. An enzyme called carnitine acetyltransferase (CRAT) then turns L-carnitine into acetyl-L-carnitine and vice versa [4].

Vegetarians consume less carnitine from the foods they eat, however, they maintain normal carnitine levels in the blood. How? The theory is that vegetarians are able to adapt to diets low in carnitine and absorb it more efficiently [3].

Under normal conditions, your body will produce sufficient amounts of carnitine and acetyl-L-carnitine. However, the following may impair the process and raise your risk of carnitine deficiency [5, 6, 7, 3]:

• Genetic disorders
• Old age
• Kidney disease
• Liver disease
• Antibiotics
• Diabetes
• Obesity
• Long-term fasting or calorie restriction
• Drugs for seizures
• Premature birth

Do athletes and bodybuilders need more carnitine? Not quite. However, they benefit from supplementation because higher levels of l-carnitine in the blood and muscles increase blood flow and oxygen supply, enhancing muscle recovery after exercise [8].

Most people use acetyl-L-carnitine to enhance their cognition and rev up energy levels. Clinical research confirms the benefits of acetyl-l-carnitine for the brain, especially in older people. We’ll cover the main ALCAR benefits below [3].

Your body makes enough acetyl-L-carnitine under normal conditions. Older people and kidney disease patients may lack L-carnitine and thus require supplementation.

• Combats depression and Alzheimer’s disease
• Reverses brain and nerve damage
• Supports mitochondrial health
• Reduces fatigue
• May help with weight loss and diabetes
• Boosts fertility

• May cause stomach upset
• May raise the risk of heart disease
• May suppress thyroid hormones

Both Acetyl-L-Carnitine (ALCAR) and L-carnitine combat fatigue and enhance fertility, but they also have some distinct benefits [9].

ALCAR boosts acetylcholine and has more pronounced effects on mental health and cognition. It also shields the brain against oxidative stress better than L-carnitine [10, 11, 12].

On the other hand, L-carnitine is a better-researched option for weight loss, physical performance, and heart health [13, 8, 14, 15].

Table 1: Uses and Benefits of Acetyl-L-Carnitine (ALCAR) vs. L-Carnitine

Brain & Nerves	Mood	Weight Loss	PhysicalPerformance	Heart Health	Fertility	Energy
ALCAR	✔	✔	✘	✘	✘	✔	✔
L-Carnitine	✘	✘	✔	✔	✔	✔	✔

Acetyl-L-carnitine (ALCAR) supplies your nerves with energy and enables the production of neurotransmitters crucial for mental health; these include acetylcholine, GABA, and glutamate [16].

It strengthens the myelin around your brain cells and stimulates their growth, helping to “regrow” your brain [16].

According to a meta-analysis of 11 clinical trials (791 patients), ALCAR is superior to placebo in reducing depressive symptoms. Its has effects comparable to standard antidepressants but causes fewer side effects [17].

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 [18, 19].

Acetyl-L-carnitine may also relieve depression in patients with mild brain damage due to liver disease (hepatic encephalopathy) [20, 21, 22].

Acetyl-L-carnitine reduces depression by protecting your nerves and boosting neurotransmitters. It has fewer side effects and acts faster than standard antidepressants.

No other neurotransmitter is more important for cognition and memory than acetylcholine; impaired cholinergic transmission is the hallmark of Alzheimer’s disease [23, 24].

As mentioned, acetyl-L-carnitine supports acetylcholine production. By boosting cholinergic activity in the brain, it prevents cognitive decline and Alzheimer’s disease [25].

It also increases brain levels of glutathione, shielding it against oxidative stress and amyloid beta plaques that destroy neurons in Alzheimer’s disease [26, 10].

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 [12].

Alzheimer’s patients receiving ALCAR had improved attention and memory, mental agility and focus (reaction time), speech and behavior [12, 27, 28].

A large review by came to a similar conclusion, though the authors emphasized most improvements were subjective [29].

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) [30].

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

The brain-protective effects of acetyl-L-carnitine (ALCAR) aren’t limited to Alzheimer’s disease. It may also improve memory and reduce mental fatigue in people of all ages.

Maintaining good brain health is especially important for the aging brain. As cells age, they become senescent: less functional and more pro-inflammatory. As a result, they produce less acetylcholine. The mitochondria of senescent cells also start breaking down, dropping energy levels in the whole body [31, 32, 33].

Research reveals ALCAR might be a way to offset senescence: it can improve mental health and cognition in the elderly [34, 35].

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 [36, 37, 38].

Many animal trials suggest that ALC supports learning, memory, and emotional health. It shields the brain and improves cognition by [39, 40, 16, 41, 42, 43]:

• Maximizing energy (ATP) production
• Boosting mitochondrial health
• Increasing acetylcholine
• Scavenging free radicals

Based on these effects, acetyl-l-carnitine might also improve cognition in younger people, though this hasn’t been researched [44, 45].

The typical changes that occur with aging can also be triggered by stress, toxins, and chronic diseases–all of which contribute to mitochondrial dysfunction and brain fog [46].

If you’re exposed to these aging-accelerators, supplementing with acetyl-l-carnitine might be a good way to protect your brain and mitochondria.

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

Acetyl-L-carnitine and alpha-lipoic acid have a powerful synergistic effect on reversing brain aging and oxidative damage, which makes them a great combination for cognitive support [47, 48, 49, 50].

Acetyl-L-carnitine combats brain aging and improves cognition, mood, and energy. A combination with alpha-lipoic acid may yield even better results.

In 96 older people, supplementation with acetyl-L-carnitine (ALCAR) improved [37]:

It also boosted mood and mental clarity while causing no side effects.

ALCAR (2 g daily) significantly improved mental fatigue and attention in 30 patients with chronic fatigue syndrome [51].

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 [52, 53].

Additionally, L-carnitine can increase energy levels and reduce fatigue, especially in people with chronic kidney disease who often lack this amino acid [54, 55].

Acetyl-L-carnitine boosts energy production and combats fatigue. It’s particularly effective in older people and kidney disease patients who often lack carnitine.

Acetyl-L-carnitine (ALC) 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 found promising results [56].

A meta-analysis of 9 clinical trials and 911 people confirmed 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 [13].

According to limited clinical evidence and animal trials, supplementation with L-carnitine may [57, 58, 8, 59, 60]:

• Improve physical performance and endurance
• Speed up recovery from exercise
• Prevent oxidative stress and cell damage
• Increase fat burning while maintaining muscle mass

However, comprehensive reviews have failed to confirm the above benefits of L-carnitine supplements in healthy people. Their effects may be limited to older or overweight people, kidney disease patients, and other groups with carnitine deficiency [61, 62, 63].

Acetyl-L-carnitine supplies L-carnitine, which may enhance weight loss, fat burning, and physical performance, but the evidence is limited.

In a meta-analysis of nine clinical trials with over 800 infertile men, a combination of L-carnitine and acetyl-L-carnitine (ALC) significantly improved sperm mobility. As a result, the chance of a successful pregnancy increased more than 4 times [64].

Women with hypothalamic amenorrhea have irregular cycles and fertility issues due to inadequate GnRH secretion. Acetyl-L-carnitine increased sex hormones and improved the symptoms in three studies with 71 women [65, 66, 67].

L-carnitine may help with PCOS, another major cause of infertility in women [68].

Acetyl-L-carnitine boosts fertility in men and women alike. A combination with L-carnitine may give the best results.

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 [69, 70].

In two meta-analyses with more than 2,000 neuropathy patients, acetyl-L-carnitine (ALCAR) significantly reduced pain and improved nerve health [71, 72].

ALCAR is a great option for diabetic neuropathy. A review of 6 clinical trials (711 patients) verified its ability to shield the nerves against toxic glucose levels in people with diabetes [73].

Anti-HIV drugs can also cause nerve damage, antiretroviral toxic neuropathy (ATN), which is a major drawback of HIV treatment. Acetyl-L-carnitine (2-3 g daily) can repair nerve damage and relieve pain and other symptoms in patients with ATN [74, 75, 76, 77].

Acetyl-carnitine has shown promising effects against chemotherapy-induced nerve damage in smaller clinical trials [78, 79].

However, it provided no benefits in a study of 409 cancer patients. It slightly worsened the symptoms of nerve damage after 6 months of treatment [80].

A limitation for neuropathy benefits is that many studies used intravenous or intramuscular treatment; oral supplementation might not have the same effects [71, 73, 75].

According to animal trials and limited clinical evidence, acetyl-carnitine may help with [81, 82, 83]:

• Carpal tunnel syndrome (hand and wrist nerve injury)
• Spinal cord injury
• Chronic pain due to nerve damage and inflammation

Impaired fatty acid metabolism and oxidative stress contribute to diabetes. Acetyl-L-carnitine (ALCAR) may help prevent diabetes or reduce the symptoms by enhancing the breakdown of fats and scavenging free radicals [84, 85].

In a small trial of 18 diabetic patients, intravenous ALCAR treatment improved glucose control [86].

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 [87].

On the other hand, l-carnitine significantly reduced blood glucose and lipids (LDL and total cholesterol) in a review of four clinical trials with 284 diabetic patients [88].

Fibromyalgia causes muscle pain, fatigue, and mood problems. 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 [89, 90].

In 65 women with fibromyalgia, ALCAR relieved pain and depression; it was equally effective as an antidepressant duloxetine [91].

Acetyl-L-carnitine was safe and well-tolerated in most clinical trials. In rare cases, it caused [17, 12, 37, 71, 92]:

• Upset stomach
• Vomiting
• Diarrhea
• 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 an increased risk of heart disease [93].

There are various ways to lower your TMAO levels, such as eating more vegetables, dietary fiber, probiotic– and resveratrol-rich foods [93, 94, 95].

L-carnitine supplementation may cause unpleasant fishy odor and suppress thyroid hormones. ALCAR might do the same, but studies haven’t confirmed this [96, 97, 98].

Acetyl-L-carnitine is safe for long-term use, but it may cause digestive side effects. It might contribute to heart disease and suppress thyroid hormones.

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 [68, 99].

Acetyl-L-carnitine appears to be safe for children, but they should use it under strict medical supervision [100, 101].

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 [17, 12, 36, 37, 71].

Most products are sold as capsules with 500 mg of acetyl-L-carnitine HCl (hydrochloride). Some also contain alpha-lipoic acid.

You will also find products with different forms of carnitine combined. “Quadracarn” contains four of them, including L-carnitine and ALCAR.

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

Most supplements contain 500 mg of acetyl-L-carnitine per capsule. Combinations with other forms of carnitine and alpha-lipoic acid are also available.

People use acetyl-L-carnitine (ALCAR) supplements to get rid of brain fog and enhance their focus and memory. Combinations with alpha-lipoic acid are popular as cognitive boosters.

Some users have also reported positive effects on their depression due to increased energy and mental clarity.

A fraction of users experienced no benefits from ALCAR supplements. The most common side effects include nausea, headache, and dizziness. It worsened anxiety in some people.

If you’re interested in natural and more targeted ways of improving your cognitive function, we recommend checking out the Limitless Mind DNA protocol. It gives genetic-based diet, lifestyle and supplement tips that can help improve your cognitive function. The recommendations are personalized based on your genes.

If you’re interested in natural and more targeted ways of improving your mood, check out this mood DNA wellness report. It gives genetic-based diet, lifestyle and supplement tips that can help improve your mood.

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Acetyl-L-carnitine (ALC or ALCAR) supplies your cells with energy and supports mental health. It increases acetylcholine levels to support cognition and lower oxidative stress in the brain.

Older people and kidney disease patients may especially benefit from supplementing. ALCAR can slow down brain aging and help with depression, Alzheimer’s disease, fatigue, and nerve damage.

Acetyl-L-carnitine is safe, but it may cause digestive side effects and headaches in some people. Pregnant women and children should skip it unless prescribed by a doctor.

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