L-carnitine, also known as levocarnitine, is a naturally occurring amino acid structure that the body produces. It plays a critical role in energy production, converting fat into energy.
Most people will get enough L-carnitine from their diet or their body’s production of this compound. Those with low L-carnitine levels may benefit from taking an oral supplement.
As well as supporting energy production, L-carnitine may help some other functions in the body, such as maintaining general brain function and reducing the risk of certain disorders.
Some people may experience mild side effects when increasing their L-carnitine intake, especially with long-term use.
This article explains current research about L-carnitine, including its benefits, effectiveness, and side effects.
L-carnitine is a type of carnitine, which
L-carnitine is a conditionally essential nutrient, meaning that the body can generally make enough of it, but, in some cases, a person may have to get the compound from food or oral supplements if they cannot make enough.
In the body, the liver and kidneys create L-carnitine from the amino acids lysine and methionine. The kidneys can also store L-carnitine for later use and eliminate the excess through the urine stream.
L-carnitine, and carnitine in general, is a key component in creating energy for the cells. Its
L-carnitine also has a secondary function of helping remove some waste products from the cells to prevent them from accumulating and causing problems.
In addition to its core functions, L-carnitine may offer the following benefits to the body.
Heart health
According to a 2024 review, L-carnitine may significantly impact heart health. It may help to reduce oxidative stress and maintain efficient energy production, which can benefit the heart muscle.
It may also have some beneficial effects for:
- heart failure
- coronary artery disease
- heart attack recovery
- peripheral vascular disease, which causes narrow arteries
However, it is important to note that L-carnitine’s heart benefits remain controversial, and further research is necessary.
Key terms explained: Oxidative stress
Oxidative stress is an imbalance of free radicals and antioxidants in the body. Free radicals are a type of reactive molecule that can accumulate and damage cells.
Cancer treatment
A small 2018 study suggests certain cancer treatments, such as chemotherapy, may cause L-carnitine deficiencies. In these cases, L-carnitine supplements may help reduce symptoms such as fatigue and weakness.
However, it is important to note that this study was very small and only looked at a sample of 11 people. No larger study has currently validated the same conclusion.
Researchers are currently studying the compound as a possible way to prevent tissue damage due to chemotherapy, but this research is in the early stages.
Diabetes
Some research suggests L-carnitine has benefits for blood sugar management in people with diabetes.
A 2023 review concludes that L-carnitine supplementation may help to reduce the following:
- fasting blood sugar levels
- HbA1c levels, which are the average blood sugar level over
90 days - insulin resistance
L-carnitine supplements cannot substitute diabetes treatments. People should speak with a healthcare professional before using this supplement if they have diabetes.
Kidney or liver disease
As the kidneys and liver help create and use L-carnitine, disease in these organs or organ failure
Doctors may recommend L-carnitine supplementation in these cases to support the function of the kidneys and liver and prevent deficiency.
Most people tolerate L-carnitine well. However, some
- stomach cramps
- nausea
- vomiting
- diarrhea
- “fishy” body odor
People with high levels of urea may also experience muscle weakness, and those with a seizure disorder may experience seizures due to high L-carnitine dosages.
Some studies suggest that high levels of L-carnitine may raise the long-term risks of cardiovascular diseases, though more research is necessary.
L-carnitine supplements may interact with certain antibiotics or anticonvulsants. Anyone considering taking L-carnitine should talk with their doctor to discuss any medications they are taking and the possible drug interactions.
It is a good idea to talk with a healthcare professional before taking L-carnitine. They may have additional recommendations to support any treatment that the person needs and can help them avoid possible reactions and interactions.
The recommended dosage is roughly 1 to 3 grams (g) per day. However, people with genetic irregularities or other health conditions causing a lack of L-carnitine should talk with their doctor for a more specific dosage.
The
Even though the body produces it naturally, carnitine is widely available in a number of simple foods. Animal proteins, such as fish, red meat, and poultry, are some of the best sources.
The NIH suggests adults with an omnivorous diet get about 24 to 145 milligrams (mg) of carnitine per day. People who avoid animal products, such as those following a vegan diet, may get around 1 to 14.5 mg from their diet.
However, the kidneys can store carnitine for later use, so people’s overall levels will be about the same, regardless of their diet. The kidneys also eliminate excess carnitine through urine to maintain healthful concentrations.
Key terms explained: Omnivorous
An omnivorous diet is a mixed diet that includes fruits, vegetables, grains, and animal products, including meat.
The best amount and form of L-carnitine may vary depending on the person’s reason for wanting more of this compound. Generally speaking, healthy adults
Athletes
Some athletes take extra L-carnitine, believing that it will boost their athletic performance.
Some research suggests this supplement may aid recovery following exercise, including muscle soreness.
However, a 2020 review notes that more research is necessary to support the use of L-carnitine for better exercise performance.
For weight loss
As L-carnitine helps burn fatty acids for energy, people
For example, a
However, L-carnitine cannot replace habits such as a balanced diet and regular exercise. It is a good idea to speak with a healthcare professional before taking L-carnitine for weight loss.
Carnitine is a broad term that describes a few different compounds. L-carnitine is a form of carnitine present in the body and many supplements. Other forms include:
- Acetyl L-carnitine: This form, sometimes known as ALCAR, also plays a role in metabolism. It possesses neuroprotective properties that may help protect the nervous system.
- D-carnitine: This type is the optical isomer (mirror image) of L-carnitine. It is toxic to the body, as it may inhibit the absorption of other forms of carnitine.
- L-carnitine L-tartrate: Athletes may take this type as a sports supplement. Research suggests that it may be useful in lowering fatigue and aiding recovery after exercise.
- Propionyl-L-carnitine: This form displays pain relieving and antirheumatic properties and may benefit heart health.
L-carnitine is an amino acid that the body naturally produces. In people with good health, the liver and kidneys produce and store enough of the compound to prevent deficiency.
People with L-carnitine deficiencies may need to get the compound through their diet or as a supplement. It is advisable to talk with a doctor before taking an L-carnitine supplement.
Some people may wish to take L-carnitine supplements for their potential benefits, such as aiding athletic performance or weight loss. However, more research is necessary to confirm these benefits.