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What Is L-Carnitine? Benefits, Dosage, and Side Effects

Miss Tooba

June 24, 2025

L-carnitine is produced by the body or obtained from the diet for the majority of people. However, taking an oral supplement may be beneficial for those with low levels of L-carnitine. This naturally occurring amino acid may aid in the creation of energy as well as other bodily processes, including preserving brain health and lowering the risk of certain illnesses. However, increasing L-carnitine intake can cause modest negative effects in some people, especially if they utilize it for an extended period.

What is L-carnitine?

L-carnitine is a type of carnitine , made up of amino acids. It performs a variety of vital bodily functions. The body uses carnitine to help break down fatty acids and convert them into energy that powers the cells.

L-carnitine is a conditionally essential nutrient , as the body can normally produce it. However, if a person's body is unable to produce enough of the chemical, they may need to obtain it from the diet or oral supplements. As a conditionally essential nutrient, L-carnitine may be insufficiently produced or obtained by people who follow plant-based diets or who have specific genetic conditions.

This amino acid is produced in the body by the liver and kidneys using the amino acids methionine and lysine. Additionally, the kidneys can store L-carnitine for later usage and excrete excess through the urine stream.

Types of carnitine:

The term "carnitine" refers to a wide range of substances. A more prevalent type of carnitine, L-carnitine, is found in numerous supplements and the body. Carnitine comes in several forms, such as:

1. Acetyl L-carnitine:

This form, also referred to as ALCAR, is involved in metabolism. The nervous system may be protected by its neuroprotective qualities.

2. D-carnitine:

This kind is L-carnitine's optical isomer. It is toxic to the body because it may prevent the body from absorbing other types of carnitine.

3. The L-carnitine L-tartrate:

Sports supplements are one way that athletes might use this kind. According to Research , it might help with healing and reduce muscle discomfort.

4. Propionyl-L-carnitine:

This type of propionyl-L-carnitine has antirheumatic and pain-relieving qualities and may be good for heart health.

Benefits of L-carnitine:

Carnitine, including L-carnitine, is essential for the production of cell energy. Its primary purpose is to keep the body's cells energized and functioning well by aiding in the breakdown of fatty acids as fuel.

Another secondary role of L-carnitine is to assist in the removal of certain waste products from the cells so that they don't build up and cause issues.

Apart from its fundamental roles, L-carnitine might offer the body other advantages. These consist of:

1. Aids in weight loss:

L-carnitine is occasionally used as a weight loss supplement because it helps transport more fatty acids into your cells for burning as fuel. A review of 37 studies conducted in 2020 found that L-carnitine supplementation dramatically decreased body weight, body mass index (BMI), and fat mass. It did not, however, affect the percentage of body fat or belly fat.

According to a 2021 assessment of 1,239 individuals with type 2 diabetes. Weight loss was also aided by taking 2 grams (g) of L-carnitine daily for at least two weeks,

However, further study is required to determine its potential effects on long-term weight loss. Additionally, even if it could help some people lose weight, you should first consult a nutritionist to create a comprehensive food and activity plan.

2. Heart health:

Research on the effects of L-carnitine on several heart health indicators is still in progress. However, it has been determined that in the short term, after a heart attack, supplements may help raise L-carnitine levels in a failing heart, which may restore circulation and heart function. Additionally, supplements may aid with heart failure symptoms like arrhythmia and chest pain.

3. Effects on brain function:

L-carnitine helps improve brain function. Research suggests that Acetyl-L-carnitine (ALCAR) may improve learning indicators and prevent age-related mental decline. A 2018 study discovered that individuals with dementia who took 1,500 mg of ALCAR daily for 28 weeks experienced a significant improvement in brain function.

4. Cancer treatment:

A person may occasionally get an L-carnitine deficiency as a result of cancer treatments like chemotherapy. Supplements containing L-carnitine may help lessen symptoms like weakness and exhaustion.

The chemical is presently being investigated as a potential means of preventing tissue damage brought on by chemotherapy, but this research is still in its early phases.

5. Kidney or liver issues:

L-carnitine deficit may result from illness in the kidneys or liver, which aid in the production and utilization of L-carnitine. In certain situations, doctors could advise taking L-carnitine supplements to support liver and kidney function and avoid deficiencies.

6. Type 2 diabetes:

L-carnitine may help those who have type 2 diabetes. According to a 2023 review , L-carnitine supplements may reduce fasting blood sugar and haemoglobin A1c. It also helps improve insulin sensitivity in diabetic patients or overweight individuals.

Insulin receptors and the expression of certain genes that control sugar metabolism are thought to be altered by L-carnitine. Additionally, beta cells, which are in charge of the pancreatic production of insulin, may benefit from it.

7. Exercise:

A review published in 2021 claims that some research indicates L-carnitine may help enhance:

Exercise, muscle repair, and oxygen delivery to muscles
Power, endurance, and workout performance
The scientists point out that some research on these parameters did not find any appreciable advantages of L-carnitine administration.

The advantages of L-carnitine might also be indirect and take weeks or months to manifest. This is not the same as supplements that can directly improve athletic performance, such as creatine or caffeine.

Food sources of L-carnitine:

Consuming meat and dairy products can provide you with small amounts of L-carnitine.

L-carnitine is best obtained from:

100 g (3.5 oz) of beef contains 139–143 mg.
Pork: 25–61 milligrams per 100 g (3.5 oz)
13–34 milligrams per 3.5 oz (100 g) of chicken
40 mg per 3.5 oz (100 g) of cow's milk
3 milligrams per 3.5 oz (100 g) of hard cheese

It's interesting to note that L-carnitine is more readily absorbed from food than from supplements.

L-carnitine dosage:

Those who want to take L-carnitine should first consult a physician. The doctor can assist the patient in avoiding potential reactions and interactions and may have other suggestions to support any treatment required.

L-carnitine is generally well tolerated. The recommended dosage is one to three grams daily. A more precise dosage should be discussed with a doctor for those who have genetic disorders or other illnesses that result in a deficiency of L-carnitine.

Side effects of L-carnitine:

L-carnitine is easily tolerated by most people. However, consuming L-carnitine may cause

digestive adverse effects in certain people. These consist of:

nausea and stomach cramps
Diarrhoea
Additionally, some people may complain of a "fishy" body odour, which is normally harmless but could be annoying.

A few studies suggest that high L-creatine levels may increase the long-term risk of cardiovascular conditions like atherosclerosis.

Supplemental L-carnitine may interfere with some anticonvulsants or antibiotics. Anyone thinking about taking L-carnitine should discuss any medications they are taking and potential drug interactions with their doctor.

Conclusion:

L-carnitine is a naturally occurring chemical that aids in the body's conversion of fat into fuel, which is essential for energy generation. Although individual outcomes may differ, it has potential advantages for male fertility, workout recovery, heart health, and brain function. Although L-carnitine is typically safe when taken as prescribed, it may not be appropriate for everyone, particularly those with specific medical issues, and may have moderate side effects, including an unsettled stomach or fishy odour. Before using any supplement, it's crucial to speak with a healthcare provider to make sure it's suitable for your needs.

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