A deeper look into L-carnitine

By Dava Stewart

The world of nutritional supplements can be confusing. Usually people who are considering taking a supplement have a particular issue they want to address. Since every person is different, with a unique set of circumstances, the first step in deciding whether or not to take a supplement should be research, including a conversation with a qualified healthcare provider.

Researching the supplement L-carnitine will yield mixed results. One website may claim the supplement helps with weight loss, while another says it is useful in treating certain heart conditions. How can consumers determine L-carnitine will work in their situations?

Begin with some basic facts:

• L-carnitine is an amino acid. Amino acids are often called the “building blocks of protein.” The body uses proteins for growth, muscle repair, digestion, and other functions. Nutritionally, meat and dairy products contain important amino acids and are the best source for L-carnitine.
•  L-carnitine plays a critical role in delivering long-chain fatty acids to the mitochondria so that they can be used to produce energy.
•     Human bodies produce L-carnitine in the liver and kidneys. It is stored mainly in the skeletal muscles, and in much smaller amounts in the heart and brain.
•     There have been numerous studies regarding L-carnitine, including its effect on athletic performance, aging, various cardiovascular diseases, AIDS and HIV, cancer, diabetes, and more.
•     Many nutritional supplements, particularly those marketed to weightlifters and other athletes contain L-carnitine.

Valid scientific studies have shown that L-carnitine is an appropriate supplement for people who have some condition that prohibits their bodies from producing the substance, or whose bodies do not properly circulate it. In those cases, the person is most likely being treated by a physician.

Various other studies are inconclusive as to whether or not L-carnitine has any impact on athletic performance. Because the majority of L-carnitine is stored in the skeletal muscles, it is rapidly depleted during even moderate exercise. However, a normal body produces enough of the substance to meet even athletic needs.

Some of the most interesting research involving L-carnitine is related to cardiovascular conditions. Several studies seem to indicate that short term use (up to one year) of the supplement can have beneficial effects on the cardiovascular system, particularly in patients with restricted blood flow to the heart (cardiovascular ischemia) or poor circulation in the legs (intermittent claudication).

Cancer patients suffering from fatigue caused by chemotherapy may benefit from taking supplemental L-carnitine. Scientific studies have shown that these patients often have a deficiency of L-carnitine. Taking the supplement showed improvement in energy levels and quality of sleep in two studies.

The kidneys regulate the amount of L-carnitine distributed throughout the body. It stands to reason that those suffering from kidney disease may have low levels and feel fatigue and heart problems, among other serious health issues. Doctors may administer very high doses of L-carnitine by injection to patients with very low levels.

The National Institutes of Health says that L-carnitine is “well-tolerated and generally safe therapeutic agent.” Although there is no conclusive evidence that taking it as a regular supplement will improve energy levels or athletic performance in a normally healthy adult, it is also highly unlikely that it will cause harm.

Sources:

umm.edu/health/medical/altmed/supplement/carnitine-lcarnitine
nlm.nih.gov/medlineplus/ency/article/002222.htm
hyperphysics.phy-astr.gsu.edu/hbase/organic/essam.html
ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/
acatoday.org/content_css.cfm?CID=3746