All you need to know about carnitine

What is L-carnitine and what is it used for ?


L-Carnitine plays a crucial role in energy metabolism, acting as a molecular transporter that facilitates the oxidation of long-chain fatty acids in the mitochondria. At the heart of these cellular energy powerhouses, fatty acids undergo conversion into ATP, constituting the body's main source of energy. This conversion is crucial not only for optimising athletic performance, but also for maintaining vitality on a daily basis.

In addition, l-carnitine has shown beneficial effects on cardiovascular health, contributing to optimal heart function and lipid profile management. For individuals aiming for improved body composition, carnitine can play a supportive role in weight management, optimising the use of fat as an energy source. Whether the aim is to improve sporting performance or maintain general well-being, carnitine is proving to be a valuable biochemical partner, helping the body to achieve an optimal state of fitness.

Carnitine or L-carnitine ?

Carnitine and L-carnitine essentially refer to the same molecule, but there is a technical nuance in their designation which is linked to the molecular structure. However, in everyday language, we always refer to carnitine. In this article we will use the 2 terms to refer to the same molecule:

  • Carnitine: The term "carnitine" refers to a molecule that plays a crucial role in energy production by transporting long-chain fatty acids into the mitochondria of cells, where they are oxidised to produce energy. It is naturally produced in the human body and can also be obtained through the diet, particularly through red meat and dairy products.
  • L-Carnitine: L-carnitine is in fact the form of carnitine that is biologically active in the human body. Organic molecules such as carnitine can exist in different forms that are mirror images of each other (called isomers). These forms are designated by the prefixes "L" and "D". In the case of carnitine, it is the "L" form (L-carnitine) that is used by the body for its metabolic functions.

In summary, although the terms are often used interchangeably, "L-carnitine" is the more precise term for the form of carnitine that is active in the human body and used in dietary supplements and therapeutic applications.

What are the health benefits of L-carnitine?

Increased fat metabolism :

L-carnitine helps transport fat into the mitochondria, where it is oxidised to produce energy. This can help increase the amount of fat you burn during exercise, which can contribute to weight loss and improved body composition.

Improving sporting performance :

Studies suggest that carnitine supplementation can improve physical performance, particularly during endurance exercise. It could help reduce fatigue and improve recovery after exercise.

Recovery support :

L-carnitine can reduce muscle damage that occurs after a workout, which can help with faster recovery and reduced muscle soreness.

Impact on muscle mass :

By supporting energy metabolism and reducing muscle fatigue, L-carnitine can also help maintain or increase muscle mass, especially when combined with resistance training.

Effects on overall health :

Carnitine, beyond its energy role, is a precious ally for the heart. Clinical research has revealed numerous benefits of L-carnitine for cardiovascular health. For example, an in-depth analysis of 10 clinical studies showed that L-carnitine can considerably reduce diastolic blood pressure, especially in overweight or obese individuals. Another analysis of 17 studies showed that L-carnitine could improve cardiac function and reduce symptoms in people suffering from congestive heart failure. In addition, a review of 2020 showed that L-carnitine could reduce total cholesterol and LDL (bad cholesterol), while increasing HDL (good cholesterol) in people at risk of heart disease. These findings suggest that carnitine could play a protective and enhancing role in the management of cardiovascular health, offering significant support for a healthy heart


It is important to note that, although L-carnitine can be beneficial, it is not a miracle solution for weight loss. A balanced diet and a regular exercise programme are essential to achieve significant results. In addition, L-carnitine is most effective when taken as part of a healthy diet and lifestyle.

Can L-carnitine improve sports performance ?


Optimising energy production :

By helping to transport fatty acids into the mitochondria to be burned as fuel, L-carnitine can improve energy efficiency, which is particularly useful during endurance exercise.

Reduced fatigue :

L-carnitine supplementation can reduce the feeling of fatigue, helping to extend exercise duration and improve endurance.

Improved recovery :

L-carnitine may contribute to faster muscle recovery by reducing muscle damage and decreasing the production of lactic acid, a by-product of intense exercise that can contribute to muscle fatigue.

Effects on muscle mass :

By supporting fat metabolism and reducing muscle breakdown during exercise, L-carnitine can help preserve muscle mass, which is beneficial for strength and performance.

Impact on fat oxidation :

By increasing the amount of fat used as energy during exercise, L-carnitine can reduce reliance on muscle glycogen stores, which can be useful during endurance activities.

It is important to stress that, although some research shows potential benefits, other studies have not found a significant effect of L-carnitine on improving sports performance The effectiveness of supplementation can vary depending on several factors, such as the amount and duration of intake, but also on the individual's physical condition and diet.

For those looking to improve their sporting performance, it is recommended that they consult a healthcare professional or sports coach for personalised advice and to determine whether L-carnitine is appropriate for their specific goals.

Is L-carnitine useful for weight loss?

It is crucial to understand that L-carnitine cannot compensate for a poor diet or lack of exercise. Generally, fat reduction occurs when there is a calorie deficit, which can be achieved through a combination of diet and physical activity.

For those considering taking L-carnitine for weight loss, it is recommended to do so alongside a balanced diet and a well-structured exercise programme. As always, it's best to consult a healthcare professional before starting any new supplement, especially if you have underlying medical conditions or are taking other medications.

Here are the 3 actions of carnitine in relation to fat loss:

  • 1. Fat metabolism: L-carnitine plays a key role in the metabolism of fatty acids by transporting them to the mitochondria to be burnt for energy. Theoretically, this could help increase the amount of fat the body burns, which could contribute to weight loss.
  • 2.Exercise and endurance: By improving endurance during exercise, L-carnitine could enable longer or more intense workouts, which could in turn increase calorie expenditure and promote weight loss.
  • 3. Fatigue reduction: By reducing fatigue, L-carnitine can help people stay active and maintain a regular level of exercise, which is beneficial for weight management.

If, and only if, you follow a suitable diet, carnitine can help you burn fat but also boost your training and so if training is more intense, or longer, so will calorie expenditure.

How and when to take carnitine ?

L-carnitine can be taken in many forms, including capsule, liquid or powder. Here's some general advice on how and when to take it to maximise its effectiveness, especially when it comes to exercise and weight loss:


  • Before exercise: Taking L-carnitine around 30 to 60 minutes before exercise can be beneficial, as this gives your body time to assimilate it and use it for fat metabolism during physical activity. Every carnitine enthusiast will testify to its obvious impact: it increases sweating in athletes during physical exertion.
  • If L-carnitine is taken in liquid form it will be more quickly assimilated.
  • With meals: Some experts recommend taking L-carnitine with a meal, particularly those containing carbohydrates and protein, as this can increase insulin levels and help transport L-carnitine into muscle cells.


The typical dose of L-carnitine is 500 to 3000 mg per day, although some studies have used higher doses. It is important to follow the dosage recommendations provided by the manufacturer or a healthcare professional.


To observe potential benefits, it may be necessary to regularly supplement your L-carnitine intake over an extended period of time... The effects are generally not immediate and may take some time to become apparent.

Form of supplement.

  • Acetyl-L-carnitine: Often used for cognitive function.
  • L-carnitine L-tartrate: Preferred for physical recovery and perhaps most effective for athletes.
  • Propionyl-L-carnitine: Generally used for blood circulation problems and associated heart disease.

Special considerations.

  • L-carnitine is best absorbed when not taken with fibre-rich food, as fibre can interfere with its absorption.
  • The addition of L-carnitine to the diet may not be essential for everyone, particularly for those who ingest an adequate amount of red meat, which is a natural source of carnitine and who do not have a carnitine deficiency. As a result, it can also be an important supplement for vegetarians.

Where can you find L-carnitine ?

L-carnitine is found naturally in several food sources, mainly in meat and animal products. Here are some of the best food sources of carnitine:

  • Red meat: The richest source of L-carnitine, particularly lamb and beef.
  • Dairy products: Milk and some cheeses contain carnitine, although in lower amounts than meat.
  • White meat: Poultry such as chicken and turkey also contain carnitine, but less than red meat.
  • Fish: Some fish and seafood are moderate sources of carnitine.
  • Vegetable foods: Although L-carnitine is mainly found in animal products, some plant foods contain small amounts, such as avocados, asparagus and peanuts.
  • Fermented foods: L-carnitine can also be found in fermented foods such as tempeh or brewer's yeast.

Het is belangrijk op te merken dat carnitinebronnen in de voeding voldoende kunnen zijn voor mensen die geen vegetariërs of veganisten zijn en die verschillende voedingsmiddelen eten, waaronder vlees en zuivelproducten. Vegetariërs en veganisten kunnen een lagere inname van carnitine hebben, maar het menselijk lichaam is ook in staat om L-carnitine in voldoende hoeveelheden te synthetiseren voor de meeste mensen, op voorwaarde dat hun dieet voldoende lysine en methionine bevat, de precursor aminozuren van carnitine.

Carnitine can be found in various supplement forms; in solid form, in capsules like in Maxi L-Carnitine or L-Carnitine 500 mg, in concentrated liquid form as in Liquid Carnitine or Carnitine 3000 mg, but also in drink form as in Carnitine 2000 mg or Immunity Water, and carnitine is also found in Vegan Protein Bars

Are there any side effects or precautions to take with L-carnitine ?

L-carnitine is generally considered safe when taken as recommended. However, as with any supplement, there can sometimes be side effects and precautions to consider:

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Possible side effects:

  • Gastrointestinal upset: High doses of L-carnitine can cause nausea, vomiting, stomach cramps and diarrhoea. But this is usually an effect that is quickly felt.
  • Body odour: Excessive consumption of L-carnitine can produce an unpleasant body odour, often described as being similar to fish, but this is fairly rare.
  • Allergic reactions: Although rare, some people can develop an allergic reaction to L-carnitine, as to almost any food.
  • Effects on blood sugar levels : L-carnitine can affect blood sugar levels, which is an important consideration for people with diabetes.
  • Drug interactions : L-carnitine can interact with certain drugs, including those used for thyroid and anticoagulants.

Precautions :

  • Pregnancy and breastfeeding: There is insufficient reliable data on the safety of taking L-carnitine in large quantities during pregnancy or breastfeeding. It's therefore best to stick to normal dietary intakes.
  • Thyroid disease: L-carnitine can interfere with thyroid hormone and could potentially worsen the symptoms of hypothyroidism or other thyroid problems.
  • Renal insufficiency: People with renal insufficiency should be cautious with L-carnitine supplementation, as this could lead to an accumulation of the substance in the blood.
  • Epilepsy: There have been reports suggesting that L-carnitine may cause seizures in people with a history of seizures.

The coach's advice.

  • When you start a weight loss program, taking carnitine before exercising can help optimize your energy metabolism. You might notice an increase in sweating, a sign of an intensified basal metabolism. This could make your workouts more effective.
  • The best way to optimize your results is to combine the intake of L-carnitine with fat burners!
  • It's essential to understand that desired fitness results are not the product of a miraculous process. They depend on a balanced diet and regular physical activity. Without these key elements, it's unlikely to achieve the set goals.
  • Also, don't forget that L-carnitine is recognized for its potential benefits beyond aiding in weight loss; it can contribute to improving lipid profiles and supporting cardiovascular health.
  • At QNT, we have various supplements to help you take a carnitine supplement: Maxi L-Carnitine, L-Carnitine 500 mg, Liquid Carnitine, Carnitine 3000 mg, Carnitine 2000 mg, Immunity Water, Vegan Protein Bars.

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