IngredientImpactMain FunctionSecondary Dosage
L-Carnitine7Fat BurnEnergy2-4 g

What is L-Carnitine?

L-Carnitine is a naturally occurring amino acid derivative that is often taken as a supplement. It is generally used to promote weight loss and can have a positive impact on brain function if used in the correct dosage.

For workout purposes, L-Carnitine plays an essential role in producing energy by transporting fatty acids into your cells’ mitochondria. These are effectively engines located within your cells, which burn the fats to create energy your body can utilise.

People need plenty of vitamin C for their body to produce L-Carnitine in sufficient amounts while eating meat or fish can also help generate it in small quantities.

L-Carnitine is a commonly used ingredient in pre-workout supplements as it has been proven to possess performance-enhancing properties.

Evidence for effectiveness

Body Composition

Pre-workout benefits of L-Carnitine

The two main variations of L-Carnitine are L-Carnitine Tartrate and Acetyl L-Carnitine.

L-carnitine Tartrate is one of the most common forms found in sports nutrition supplements due to its rapid absorption rate. It is found in its highest levels in tissues that use fatty acids as the primary fuel source and should be taken in conjunction with a healthy, balanced diet and exercise regime.

Acetyl L-Carnitine is created in the body from the amino acids lysine and methionine and is ideal for athletes who partake in regular exercise. Many scientific studies recommend taking L-Carnitine about one hour before your workout, although some research has shown it can be effective if taken after exercise.

L-Carnitine’s benefits can be indirect and take months to appear, unlike the more immediate results delivered by supplements such as creatine and caffeine.

The benefits of L-Carnitine include improved recovery from workouts and increased oxygen supply to your muscles. It has been proven to increase blood flow and nitric oxide production, helping to delay discomfort, reduce fatigue and lower muscle soreness. L-Carnitine may also increase the production of red blood cells, which transport oxygen throughout your body and muscles.

The latest science

L-Carnitine has long been investigated as an ergogenic aid for enhancing exercise capacity in the healthy athletic population.

Some early research indicates beneficial effects on acute physical performance, such as higher power output and increased maximum oxygen consumption.

Other studies highlight the positive impact of L-Carnitine on the recovery process after exercise, particularly regarding muscle injury and cellular damage.

L-Carnitine has also been proven by recent research to provide increased muscle mass, lower body weight and reduce fatigue in older adults.

A prolonged study into L-Carnitine discovered it did not significantly affect muscle strength in healthy aged women, suggesting the benefits may be gender-specific.

The National Institutes of Health (NIH) go a step further, saying that healthy people do not need extra L-Carnitine from food or supplements.

They argue that adults who eat a mixed diet that includes red meat, poultry and other animal products get enough L-Carnitine for their workout needs.

Other health benefits of L-Carnitine

L-Carnitine has been shown to have the potential to reduce blood pressure and the inflammatory process associated with heart disease.

One study showed that taking two grams of Acetyl-L-Carnitine per day can produce a 10-point drop in systolic blood pressure.

L-Carnitine has also been strongly linked to improvements in patients with coronary heart disease and chronic heart failure.

It may also reduce symptoms of type 2 diabetes and its associated risk factors, with one study showing that L-Carnitine supplements can significantly lower blood sugar levels.

L-Carnitine can also combat diabetes by increasing a key enzyme called AMPK, which improves your body’s ability to use carbohydrates effectively.

What to look for on the label

The research into the best doses of the two main variations of L-Carnitine is conflicting, although the following are deemed to be the optimal ranges:

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

For most people, two grams or less per day is relatively safe and free from any severe side effects when used over a long-term period.

One study discovered that people who took three grams every day for 21 days experienced no adverse effects.

Synergistic effect with other pre-workout ingredients

It is widely believed that L-Carnitine works synergistically with other pre-workout ingredients, and there appears to be very little evidence suggesting otherwise.

However, some studies have shown side effects such as mild nausea and stomach discomfort have been caused by L-Carnitine supplements.

It has been found that L-Carnitine may raise your blood levels of trimethylamine-N-oxide (TMAO) over time, which could lead to clogged arteries.

This is unlikely to occur if people stick to the recommended dosage, although further studies are needed before a definitive opinion can be provided.

L-Carnitine has been found to interact with some blood clotting medicines, so speak to a medical professional before using any products containing this.

It has also been shown to decrease how well thyroid hormone works, which would have a negative impact on metabolism, growth and many other bodily functions.

In summation, while there are some mixed messages concerning L-Carnitine, there is undoubtedly plenty of evidence that it provides useful workout benefits.

L-Carnitine supplements may also benefit people with lower levels of lean muscle, such as older adults, vegans and vegetarians.