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.
What is Acetyl-L-Carnitine?
Amino Acid Fuel
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 .
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 .
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 .
Who Needs It?
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
- 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 .
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 .
- 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
Acetyl-L-Carnitine vs. L-Carnitine
Table 1: Uses and Benefits of Acetyl-L-Carnitine (ALCAR) vs. L-Carnitine
1) Combats Depression
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 .
2) Helps with 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 .
A large review by came to a similar conclusion, though the authors emphasized most improvements were subjective .
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) .
3) May Enhance Cognition and Shield the Brain
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.
Studies in Older People
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].
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].
Overall Brain Protection
- Maximizing energy (ATP) production
- Boosting mitochondrial health
- Increasing acetylcholine
- Increasing glutathione, the body’s master antioxidant
- Scavenging free radicals
- Preventing brain aging caused by lactate buildup in the brain
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 Synergy
Alpha-lipoic acid is another potent antioxidant that protects the nerves against diabetes and other conditions with increased oxidative stress.
4) Reduces Fatigue
In 96 older people, supplementation with acetyl-L-carnitine (ALCAR) improved :
It also boosted mood and mental clarity while causing no side effects.
5) May Support Weight Loss and Bodybuilding
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 .
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 .
- 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].
6) Improves Fertility
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 .
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 .
7) Repairs 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 [69, 70].
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].
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 .
- Carpal tunnel syndrome (hand and wrist nerve injury)
- Spinal cord injury
- Chronic pain due to nerve damage and inflammation
8) May Help With Diabetes
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 .
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 .
9) Reduces Fibromyalgia Symptoms
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 .
Acetyl-L-Carnitine Side Effects & Precautions
- Upset stomach
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 .
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 Dosage & Supplements
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.
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.
Want More Targeted Ways to Enhance Mood and Brain Function?
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.