L-carnitine | What is it? Benefits, When To Take It & Dosage

 An Introduction to L-carnitine

When you exercise, a thousand biochemical reactions are taking place inside your body. Glycogen is taken from inside muscle cells and is broken down into glucose. This then enters the bloodstream and travels to the mitochondria – the organelles responsible for providing your cells with energy. Enzymes come into action and start to break down stored fat into fatty acids and glycerol to be used as fuel throughout the exercise. L-carnitine is a compound that plays an important role in this process.

The intensity and duration of your workout depends on how optimised your body is at using fat for fuel. Wouldn’t it be nice if there was a supplement that could boost fat oxidation so you can keep exercising longer?

Well, in fact, there is. It is called L-carnitine and has been used by athletes from different sports around the world to improve performance. It is one of the most popular supplements for weight loss and fat burning.

What Is L-carnitine?

L-carnitine is a non-essential amino-acid-like compound, meaning it’s produced in the body naturally. Its main function is to help the body to produce energy and plays an important role in muscle movement as well as the normal functioning of the brain and heart.

L-carnitine is responsible for escorting long-chain fatty acids to your cells’ mitochondria, where energy is produced. L-carnitine also ushers toxic by-products of energy production out of your cells preventing them building up. Approximately 98% of the body’s L-carnitine stores are found in the muscles, along with trace amounts in the liver and blood.

In some cases, L-carnitine is conditionally-essential meaning the body does not produce sufficient amounts of the compound. Supplements might be essential for these individuals and are particularly recommended for people who have a genetic condition or are undergoing medical procedures that use up the body’s L-carnitine supply.

They are also recommended to anyone whose diet affects the amount of L-carnitine in their body, for example, vegans or strict vegetarians. This is because natural food sources of L-carnitine include primarily animal products like beef, pork, chicken and milk, although it can be found in some plant products such as avocado and soybeans.

 Types Of L-carnitine & Their Uses

The two main variations of L-carnitine that are supplemented in the diet are L-carnitine tartrate and acetyl L-carnitine.

1. L-carnitine Tartrate

L-carnitine Tartrate is created in the body from the amino acids lysine and methionine. It is mainly synthesised in the liver and kidneys and must be transported for use to other tissues in the body. It is found in its highest levels in tissues that use fatty acids as the main fuel source such as the skeletal and cardiac muscles. It is recommended to consume 1 serving of L-carnitine 2-3 times daily with meals for best results. L-Carnitine should be taken with a healthy balanced diet.

2. Acetyl L-carnitine (ALCAR)

Acetyl L-carnitine is created in the body from the amino acids lysine and methionine. The main difference between ALCAR and L-carnitine tartrate is that ALCAR has an acetyl group attached to the carnitine molecule which changes its functionality and allows it to pass through the blood-brain barrier.

This means it is often found in the nervous system, particularly the brain and is the preferred choice of supplement for brain support (more on these benefits in a moment). ALCAR is ideal for athletes and active people who take part in regular exercise or anyone looking for an easy-to-consume source of L-carnitine that can be taken throughout the day.

Benefits Of L-carnitine 

1. L-carnitine & Weight-loss

L-carnitine helps your body to produce energy by utilizing the body’s fat stores allowing you to work-out for longer and ultimately aiding in fat loss. Taking L-carnitine on a daily basis has been proven to increase the blood and muscular concentrations of this amino acid-like compound, enhancing fat metabolism.

2. L-carnitine & Exercise Performance

Given its fat burning capabilities, L-carnitine optimises how your body uses fat for fuel allowing you to exercise for longer. Research has also found that muscle lactate was reduced when performing high-intensity exercise (at 80% VO2max). This is not the first study to show that L-carnitine supplementation is able to reduce various markers of metabolic stress and muscle soreness. Similar results were found by Spiering et. al. (2007) (3) and Jacobs et. al. (2009) (4).

3. L-carnitine & Brain Function

L-carnitine may also benefit brain function. ALCAR has been proven to positively impact learning capacity. In experimental models carried out on rats, it has been found that the ALCAR-treated subjects had a superior learning capacity compared to those in the control group when subjected to a maze memory test.

In human studies, taking ALCAR daily helped to reverse the decline in brain function associated with Alzheimer’s Disease and other brain pathologies. Pilot studies on dementia patients have helped to reveal the effective impact on Alzheimer’s Disease; subjects scored better for memory, attention, language, visuospatial, and constructional abilities following ALCAR supplementation.

In another study, acetyl L-carnitine showed signs of protecting your brain from cell damage. The study involved alcoholic subjects taking two grams of acetyl-L-carnitine per day for 90 days. These subjects showed significant improvements in all measures of brain function.

When to Take L-carnitine?

Studies have shown that the L-carnitine-carbohydrates combination has ergogenic effects and can increase work output by 11%. So you should take your L-carnitine supplement with a reasonable amount of fast-acting carbohydrates (e.g. 60g of dextrose or maltodextrin).

Whilst there is some evidence to suggest L-carnitine can take effect approximately 30-45 minutes after consumption, the “before or after workout” dilemma ultimately doesn’t seem to be the most important factor when considering L-carnitine supplementation. Rather, take it daily for some weeks and you should be able to see some solid results.

 L-carnitine Dosage – How Much Do You Take?

The usual dose of L-carnitine is 500–2,000 mg per day, but varying studies suggest different doses for each form of L-carnitine.

  • Acetyl-L-Carnitine: 600–2,500 mg per day.
  • L-Carnitine L-Tartrate: 1,000–4,000 mg per day.
  • Propionyl-L-Carnitine*: 400–1,000 mg per day.

*Propionyl-L-carnitine shares similar benefits to other variations of L-carnitine and is known for its ability to protect against free radicals and assist in energy production.

Myprotein’s L-carnitine Tablets come in 1000mg servings, which as a dietary supplement we recommend taking as two tablets one-two times a day.

Take-home Message

Made famous as a fat-burner, L-carnitine’s ability to move more fatty acids into your cells to be burned for energy also makes it an effective performance aid.

Though it is widely known as an effective weight loss and performance supplement, much of the convincing evidence points towards improving brain function, capacity and long-term memory.

The various forms of L-carnitine are top supplements for vegans and vegetarians who don’t easily acquire it from natural food sources, as well as elderly people who often have difficulties producing sufficient amounts naturally.

The most popular types include Acetyl-L-Carnitine which is most commonly associated with brain health and function, L-Carnitine L-Tartrate which is most effective for improving exercise performance, and Propionyl-L-Carnitine which is best for improving blood flow in those with high blood pressure or related health conditions.

So now you’re clued up on L-Carnitine, we want to help you boost your workout even further – that’s why we’re offering our Zone readers an exclusive free sample of Mypre. Click here to get yours!


1 – Altern Med Rev. 1998 Oct;3(5):345-60

2 – J Physiol. 2011 Feb 15;589(Pt 4):963-73

3 – J Strength Cond Res. 2007 Feb;21(1):259-64

4 – J Int Soc Sports Nutr. 2009 Apr 2;6:9



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