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L-Carnitine Benefits, Side Effects & Safety Information

Published: 13th May 2018. Last updated: 21th July 2019.

Luna Smithton

Editor & Fact Checker


Acetyl-l-carnitine (ALCAR) is an amino acid - a building block for protein - found in nearly all cells of the body. Its main role is helping your cells produce energy.

Acetyl-l-carnitine transports lipids and fatty acids into the mitochondria – which encourages fat to breakdown inside the cells. Due to this particular effect, acetyl-l-carnitine has been recommended by some experts as a supplement to those who are trying to lose weight.

Acetyl-l-carnitine is often used to treat various mental disorders, such as Alzheimer’s disease, late-life depression, thinking problems (particularly related to alcoholism, Lyme disease and very poor liver function), and improving memory problems in elderly people.

It is also used to treat poor blood flow to the brain, nerve pain due to diabetes and drugs used in the AIDS treatments and Down syndrome.

Men may use acetyl-l-carnitine to treat infertility caused by inflammation of some reproductive organs and tissues, and symptoms of “male menopause” - low testosterone levels due to aging. In addition to that, acetyl-l-carnitine is used for a disease affecting the fibrous scar tissue of the penis called Peyronie’s disease.

Whereas acetyl-l-carnitine is most commonly used for treating various mental disorders, it is also often taken as a supplement. Due to the many ways it benefits both the brain and the body, it is particularly popular among bodybuilders, those looking to enhance their cognitive function and/ or energy, those aiming to lose weight and promote heart health.

The Potential Benefits of L-Carnitine

Below we have listed everything we believe could be viewed as a potential benefit, based on credible scientific studies:

It May Help With Weight Loss

Acetyl-l-carnitine performs a key function of transporting lipids and fatty acids into the mitochondria, which encourages fat to breakdown inside the cells.

Because it supports fat metabolism [1], Acetyl-L-Carnitine has been recommended by some authors as a supplement for those who are aiming to lose weight. It could be particularly beneficial for those who combine dieting with physical activity, as it has been found to be effective in enhancing overall athletic performance [2], leading to boosted energy levels and increased metabolism.

It May Improve Cognitive Function

Acetyl-l-carnitine has been found to be very effective in boosting cognitive function [3], particularly in areas like memory [4], ability to learn and thought processing.

It has been found that supplemental acetyl-l-carnitine nourishes neurotransmitters in your brain, and boosts levels of acetylcholine - the primary neurotransmitter involved in memory.

The nutrient is widely used to treat several mental disorders, and supplemental acetyl-l-carnitine could be used by healthy individuals to help improve not only memory, but other cognitive functions, such as levels of attention and focus.

It May Help Increase Athletic Productivity

Acetyl-l-carnitine is commonly used in the athletic community due to its multiple benefits related to sports and nutrition. Firstly, it effectively boosts energy levels - but the effect is natural and differs from the effect caffeine has.

In addition to that, people who do sports opt for acetyl-l-carnitine as a supplement because of its ability to help burn fat (i.e. boost fat loss). Moreover, the supplement helps your muscles recover after a workout - as well as minimize the damage [5] done during the workout.

Studies have shown that ALCAR helps reduce recovery time after an intense work-out, due to enhanced oxygen uptake in the muscles. [6]

It May Help Protect Your Heart Health

Multiple studies have shown that ALCAR also directly supports the heart. It is a powerful nutrient which works to nourish the autonomous nervous system that regulates heart rhythms.

As fatty acids are the fuel of our hearts (not sugar, as it is often believed), the heart needs the body to be able to efficiently burn fat for fuel for normal energy production (also known as beta oxidation). Acetyl-l-carnitine is a source of carnitine – the specific nutrient the body must have to perform beta oxidation. [7]

It May Be An Effective Neuroprotectant

Due to its antioxidant properties, acetyl-l-carnitine acts as a neuroprotectant, meaning that it works to prevent and repair damage caused by free radicals.

It helps the brain eliminate other toxins and is also thought to be effective in reducing cell death, caused by excitotoxicity (the process by which nerve cells are damaged or killed due to excessive stimulation).

Moreover, acetyl-l-carnitine has been found to improve the neural network and has even been shown to protect the brain against the harmful effects of alcohol. [8]

How To Use L-Carnitine

As a supplement, acetyl-l-carnitine can be taken with or without food – but it has been found to be more effective when taken with a meal.

Since supplement ingredients vary greatly from maker to maker, establishing a standard dose is difficult.

For supplemental use, the dosage ranges from 250-500mg per day to 3g. It is recommended that you do not exceed 3g.

Before beginning to use acetyl-l-carnitine, it is recommended that you speak with your doctor, who will be able to determine the best dosage of the supplement for your needs.

Are There Any Foods That Contain L-Carnitine?

Acetyl-L-Carnitine is naturally present in a range of foods we consume daily. Higher amounts of it are found in dairy and meat products, meaning that vegetarians and vegans may be the groups that need supplementation the most. Here are the food products that contain acetyl-l-carnitine:

  • Red meat – beef, veal, pork.
  • Dairy – milk, cheese, ice cream.
  • Poultry and fish – chicken, codfish.
  • Other sources – avocado, tempeh, asparagus, whole-wheat bread, peanut butter.

L-Carnitine Side Effects List

Since Acetyl-L-Carnitine is a natural supplement, the risk of potential negative side effects is low.

However, it is worth knowing about the side effects it could have, so you can make sure you are fully aware of the potential risks.

The following side effects could potentially be:

  • Stomach upset
  • Nausea
  • Vomiting
  • Dry mouth
  • Headaches
  • Restlessness [9]

Note: these side effects are possible but may not be the typical user experience.

Is L-Carnitine Safe?

Acetyl-l-carnitine is highly safe and has been found to be well-tolerated. The side effects it could cause are rare, and even when they are experienced, they are minor and only associated with high dosage.

However, prior to using acetyl-L-carnitine, you should consult with your doctor if you have any kind of medical condition or are taking other supplements or drugs.

Acetyl-l-carnitine could increase the effect of many drugs, including natural herbs and supplements.


Acetyl-l-carnitine has been found to be remarkably effective in treating various mental disorders, age-related illnesses and certain physical diseases.

Taking it in supplemental form can also significantly boost certain areas of your wellbeing such as heart health, cognitive function (memory, focus, ability to learn), athletic productivity and healthy weight loss.

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