L-carnitine: Proven Benefits, Risks, and More
This article covers what L-carnitine is and some of its benefits.
L-carnitine is derived from an amino acid and is found in almost all the cells in the body. The word comes from the Latin, carnus, or flesh, being that the L-carnitine compound is isolated from meat. L-carnitine plays a role in energy production and is concentrated in skeletal and cardiac muscles.
For most people, the body naturally produces enough L-carnitine to meet their needs. But for some individuals, such as preterm infants or those with genetic or medical conditions, the body can’t make enough L-carnitine. For these individuals, L-carnitine is considered an essential nutrient.
L-carnitine is mostly found in animal products, such as meat, fish, poultry, and dairy. The redder the meat is, the higher it is in L-carnitine. For instance, 4 ounces of cooked beef steak contains 56–162 milligrams of L-carnitine. In dairy products, L-carnitine is primarily found in the whey portion.
People may supplement with L-carnitine for many reasons, such as athletic performance, fat burning, aging, cardiovascular protection, cancer, and infertility. However, the Food and Drugs Administration (FDA) has approved the supplementation of L-carnitine only for people with a true deficiency.
Some people receiving certain treatment, such as hemodialysis, may also be deficient in L-carnitine.
Some people take L-carnitine to improve athletic performance. However, there is very limited research to show that supplementation with L-carnitine improves athletic performance in healthy individuals.
In people without a fatty acid oxidation defect, the benefits of L-carnitine are likely to be minimal.
L-carnitine is frequently marketed as a weight loss supplement, but the research is inconclusive. Some research suggests that oral L-carnitine might reduce fat mass, especially in people with overweight or obesity.
L-carnitine is thought to play a role in the aging process because its concentration in bodily tissues decreases with age, causing a decline in mitochondrial function.
Type 2 diabetes
Researchers noted some positive effects of the supplement on blood sugar, but it was not always statistically significant. There were other effects on reducing some symptoms of type 2 diabetes, including fatigue and insomnia, after 6 months of treatment.
The researchers concluded that much more research is needed. Still, L-carnitine could one day be a beneficial supplement in people with type 2 diabetes alongside their recommended treatment and the Mediterranean diet.
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Cardiovascular and peripheral arterial disease
Some research has found that L-carnitine supplementation and standard pharmacological treatment after a heart attack reduce mortality and subsequent occurrences of chest pain. However, not all studies have found this.
Some other research has found that taking L-carnitine can help reduce muscle cramping in individuals with peripheral arterial disease. This cramping is called claudication and results from an inadequate supply of oxygen-rich blood to the legs.
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L-carnitine may be of value for treating male infertility because carnitine content in seminal fluid is directly related to sperm count and motility. Several studies suggest that L-carnitine may improve sperm quality and reduce cell death in the testes.
However, more research is needed to determine the overall effects of L-carnitine on male fertility.
High doses of L-carnitine can cause diarrhea and gastrointestinal distress.
Other side effects include:
Generally, the side effects of taking L-carnitine are mild.
People who decide to take L-carnitine should do so under the supervision of their doctor in case there are interactions with other medications or supplements.
Because more research is needed on the benefits of L-carnitine, people should be aware that they may not always see desired effects from L-carnitine supplementation.
Always talk with your doctor before starting any new supplement, especially if you have an underlying condition. Your doctor will be able to tell you more about its safety in your circumstances and will also be able to recommend other measures to help you achieve your aims.
L-carnitine can interact with other medications. People taking the following medications should be aware of the following possible interactions with L-carnitine:
- pivalate-conjugated antibiotics, such as pivampicillin, used to prevent urinary tract infections
- some anticonvulsants, including:
- valproic acid
According to the 2020–2025 Dietary Guidelines for Americans, most people can and should meet their required daily amount of L-carnitine through their food intake rather than supplements.
Exceptions to this are people who have a medical reason to take a supplement, such as people who are pregnant or have a specific medical condition.
For individuals who need to take L-carnitine supplements, their doctor will recommend the appropriate dosage for them. However, they should never exceed 3 g per day, as this can cause side effects.
L-carnitine is derived from amino acids and plays a role in energy production. Most people naturally produce enough L-carnitine to meet their body’s needs.
L-carnitine is found in animal products, with the highest concentrations found in red meat. Although many people take L-carnitine supplements, more research is needed on its benefits.
You should talk with your doctor before taking L-carnitine supplements, especially if you have certain medical conditions or take prescription medications.