L-carnitine: what is it and how does it work in our body?

Nutritional supplements with L-carnitine have become popular in recent years to improve sports performance and to promote weight loss, in addition to other uses of character doctor.

But what is L-carnitine exactly? How does it work in our body? And, most importantly, is it truly effective in all your applications? In this article we will answer these questions.

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What is L-carnitine?

L-carnitine is an amino acid produced by the kidneys and liver and that is stored in the brain, heart, muscles and sperm. It is involved in the transformation of fat into energy and antioxidant properties are attributed to it.

It is one of the two isomers or molecular structures of carnitine. While L-carnitine has positive effects on the body, the other isomer, D-carnitine, inhibits the activity of L-carnitine.

L-carnitine found mainly in red meat, especially in lamb and veal. It can be found in moderate amounts in pork, cod, chicken breast and in dairy, and there is also a small concentration of this amino acid in some vegetables and cereals.

This compound is used as a supplement to treat various disorders of the body and to enhance metabolic activity. However, not all of its applications have been endorsed by scientific research.

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How does it work in the body?

L-carnitine serves to transport fatty acids across the mitochondrial membranes of cells. The enzyme carnitine palmitoyltransferase binds L-carnitine molecules to fatty acids.

This amino acid has antioxidant effects: eliminates free radicals, particles that, if accumulated in excess, alter DNA and damage cells by oxidation, which may favor the appearance of cancer.

L-carnitine deficiencies can occur in the body due to genetic alterations or malnutrition, as well as the exclusive consumption of plant foods.

The lack of L-carnitine can cause different alterations depending on the age, severity and organs involved. Some of the most characteristic symptoms of this alteration are the reduction in the levels of glucose (hypoglycemia), the development of diseases of the heart muscle (cardiomyopathy) and the fatigue.

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What is it for?

The uses for L-carnitine as a nutritional supplement are multiple, although not all of its supposed benefits have been proven and much remains to be investigated. In this section we will detail the scientific evidence regarding the different applications of this substance.

In no case is it recommended to take L-carnitine supplements without a prescription since it is a drug in the experimental phase in most of its applications.

1. Kidney disease

The kidneys participate in the production of L-carnitine, so that the blood levels of this amino acid are affected when there is kidney disease. It is in this field that external L-carnitine is most clearly effective.

L-carnitine supplements have been shown to be effective as an adjuvant for people undergoing Hemodialysis, a form of therapy that replaces the function of the kidneys when they are not working properly. This not only reduces the symptoms of L-carnitine deficiency but can also prevent them.

2. Cardiovascular disorders

Scientific studies have found preliminary evidence in favor of the use of L-carnitine in diseases of the heart and the circulatory system in general.

Specifically, L-carnitine can increase the capacity for physical exertion of people diagnosed with angina pectoris or heart failure, as well as reducing the risk of mortality after heart attacks and in cases of cardiac inflammation (myocarditis).

On the other hand, it has been suggested that L-carnitine reduces pain and improves mobility in people with atherosclerosis, and that it prevents the appearance of this disorder by reducing cholesterol levels and triglycerides.

3. Weightloss

There is not enough scientific evidence to affirm that L-carnitine is effective as a supplement to reduce weight, despite the fact that this is one of its most famous applications.

Some studies claim that this compound reduces fat accumulation and increases muscle mass. In addition, the effects of L-carnitine to reduce fatigue would facilitate weight loss indirectly.

4. Male infertility

Male infertility has been linked with low levels of L-carnitine. Research shows that supplements of this amino acid are likely to increase the number and motility of sperm.

5. Diabetes

L-carnitine can help regulate blood glucose levels of people with diabetes if it is taken as a supplement to specific medication to treat this disease.

In the same vein, it may be effective in reducing the symptoms of diabetic neuropathy, which is occurs when elevated glucose levels damage the nerves in the extremities, causing pain and numbness.

6. Hyperthyroidism

L-carnitine seems to reduce the symptoms of hyperthyroidism, a disorder characterized by excessive secretion of thyroid hormones. The studies in this regard are promising but inconclusive at the moment.

Typical symptoms of hyperthyroidism include tachycardia, anxiety, insomnia, physical weakness, and tremors.

7. Erectile dysfunction

Although more studies are needed to confirm this, it has been suggested that L-carnitine can increase the effectiveness of Viagra in cases of impotence, especially in men who do not respond adequately to this medicine and who have undergone prostate surgery.

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8. Fatigue

There is preliminary scientific evidence regarding the usefulness of L-carnitine for reduce age-related fatigue, cancer, celiac disease, hepatitis, multiple sclerosis and chronic fatigue syndrome, as well as fatigue in general.

9. Sports performance

Intense physical exercise has been linked to a decrease in L-carnitine levels, so many athletes use these supplements to improve their performance. However, and although some studies support this hypothesis, it cannot be said that L-carnitine is useful for improving athletic performance.

Bibliographic references:

• Steiber A., ​​Kerner J., Hoppel C.L. (2004). Carnitine: a nutritional, biosynthetic, and functional perspective. Molecular Aspects of Medicine. 25 (5–6): 455 - 473.
• Vaz F.M., Wanders R.J.A. (2002). Carnitine biosynthesis in mammals. Biochem. J. 361: 417 - 429.
• Wall B.T., Stephens F.B., Constantin-Teodosiu D., Marimuthu K., Macdonald I.A., Greenhaff P.L. (2011). Chronic oral ingestion of L-carnitine and carbohydrate increases muscle carnitine content and alters muscle fuel metabolism during exercise in humans. PubMed.gov.