Key takeaways
- L-carnitine, a naturally occurring amino acid derivative, plays a vital role in energy production by transporting fatty acids into cells’ mitochondria.
- While L-carnitine supplementation may aid in weight loss, improve brain function, and benefit heart health and type 2 diabetes, the evidence is mixed. Consulting a healthcare professional is recommended to determine its appropriateness.
- L-carnitine supplementation is generally safe at doses of 2 grams or less per day, though mild side effects are possible. It can be obtained from meat and dairy products, which are absorbed more readily than supplements.
L-carnitine is an amino acid derivative produced in the body, found naturally in some foods, and often taken as a supplement. It plays a key role in energy production by transporting fatty acids into your cells’ mitochondria.
The mitochondria act as engines within your cells, burning these fats to create usable energy. Your body can produce L-carnitine out of the amino acids lysine and methionine.
More than
You can also obtain small amounts by eating animal products, such as meat and dairy. People who eat plant-based diets or those with certain genetic conditions may be unable to produce or obtain enough L-carnitine, making it a conditionally essential nutrient.
Keep reading to learn more about the possible functions, risks, and benefits of L-carnitine.
A note on L-carnitine supplements
Some people suggest that L-carnitine supplements may have some health benefits, including increased weight loss and improved brain function.
However, popular claims about supplements and those listed on a product for marketing purposes don’t always match up with the science.
Dietary supplements like L-carnitine are not regulated by the
Before taking any dietary supplements, consider speaking with a healthcare professional. They can advise you on the best type and dosage of supplement to take, if appropriate.
L-carnitine helps transport more fatty acids into your cells to be burned for energy, so it’s sometimes used as a weight loss supplement.
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Another 2021 review in 1,239 people with type 2 diabetes found that taking 2 grams (g) of L-carnitine daily for at least 2 weeks helped promote weight loss.
Still, more research is needed to understand how it may impact long-term weight loss.
Furthermore, while it may aid in weight loss for some people, consider speaking with a dietitian to develop a thorough diet and exercise regimen first.
L-carnitine may benefit brain function.
Some research suggests that the acetyl form, acetyl-L-carnitine (ALCAR), may help prevent age-related cognitive decline and improve markers of learning.
In fact, a 2018 study found that taking 1,500 milligrams (mg) of ALCAR daily for 28 weeks significantly improved brain function in people with dementia.
However, other studies have turned up mixed results.
For instance, a 2017 review showed that taking L-carnitine for 3 days had no effect on markers of brain function — including reaction time, vigilance, immediate memory, and delayed recall — in young adults without cognitive impairment.
Therefore, further research is needed to assess the potential benefits of supplementation.
Some studies demonstrate that L-carnitine may benefit several aspects of heart health.
According to a 2024 review, L-carnitine may support heart health by strengthening the heart muscle and helping it contract and pump blood more effectively.
What’s more, a
Another
The evidence is mixed regarding the effects of L-carnitine on sports performance, but it may offer some benefits. According to a 2021 review, some studies suggest that L-carnitine may help improve:
- exercise and muscle recovery
- muscle oxygen supply
- exercise performance, endurance, and power
However, the researchers note that some studies found no significant benefits from L-carnitine supplementation on these parameters.
L-carnitine’s benefits may also be indirect and take weeks or months to appear. This differs from supplements like caffeine or creatine, which can directly enhance sports performance.
Consider speaking with a healthcare professional before taking L-carnitine to boost exercise performance. They may suggest a better alternative for you.
L-carnitine may be beneficial for people with type 2 diabetes.
A 2023 review concluded that L-carnitine supplementation may reduce fasting blood sugar and hemoglobin A1c, while also improving insulin sensitivity in people with diabetes, overweight, or obesity.
L-carnitine is believed to work by altering insulin receptors and changing the expression of specific genes that regulate sugar metabolism.
It may also help improve the function of beta cells, which produce insulin in the pancreas.
Some research suggests that L-carnitine could be beneficial for the treatment of depression.
In a
Several studies included in this review also found that acetyl-L-carnitine was as effective as antidepressant medications but caused fewer adverse effects.
Still, more research is needed to understand how L-carnitine may affect depression.
For most people, taking 2 g or less per day is relatively safe and unlikely to cause serious side effects. But some mild side effects like heartburn and indigestion are possible.
Some studies have also used doses up to 4,500 mg per day.
It’s important to note, however, that L-carnitine supplements may raise your blood levels of trimethylamine-N-oxide (TMAO) over time. High levels of TMAO are linked to an increased risk of atherosclerosis — a disease that clogs your arteries.
More studies on the safety of L-carnitine supplements are needed.
You can get small amounts of L-carnitine from your diet by eating meat and dairy products. The best sources of L-carnitine are:
- Beef: 139 to 143 mg per 3.5 ounces (oz), or 100 g
- Pork: 25 to 61 mg per 3.5 oz (100 g)
- Chicken: 13 to 34 mg per 3.5 oz (100 g)
- Cow’s milk: 40 mg per 3.5 oz (100 g)
- Hard cheese: 3 mg per 3.5 oz (100 g)
Interestingly, food sources of L-carnitine have a greater absorption rate than supplements.
According to a 2004 study,
Your body also produces L-carnitine naturally from the amino acids methionine and lysine if your stores are low.
As such, L-carnitine supplements are only necessary in special cases, such as disease treatment.
Your L-carnitine levels are influenced by both what you eat and how much your body produces.
Vegans and vegetarians
L-carnitine levels are often lower in vegetarians and vegans since they restrict or avoid animal products, according to
Therefore, vegetarians and vegans may want to consider L-carnitine supplements, which can help normalize carnitine levels in the blood and muscles.
Older adults
Older adults may also benefit from L-carnitine supplements.
A 2016 study found that taking 1.5 g of L-carnitine per day for 10 weeks improved functional status and frailty in older adults.
On the other hand, a 2018 study showed that L-carnitine supplementation had no effect on muscle strength or markers of inflammation in older women.
Chronic conditions
The risk of deficiency is higher for those with diseases like cirrhosis and kidney disease. If you have one of these conditions, a supplement may be beneficial.
However, as with any supplement, you should speak with a doctor before taking L-carnitine.
Studies on the potential benefits of L-carnitine have used a wide range of doses.
Dosage varies from study to study and may vary depending on the form of carnitine you take:
- Acetyl-L-carnitine: This form is best for brain health and function. Doses vary from 500 to 3,000 mg per day.
- L-carnitine L-tartrate: This form is most effective for exercise performance. Doses vary from 1,000 to 4,500 mg per day.
- Propionyl-L-carnitine: This form may help improve blood flow in those with high blood pressure or related health conditions. A 2005 study used a dose of
2 g per day .
Some research suggests that taking 500 to 510 mg of L-carnitine daily may help treat narcolepsy, a sleeping condition characterized by abnormal sleeping patterns.
Some research suggests that L-carnitine may reduce body weight, BMI, and belly fat in people with polycystic ovary syndrome (PCOS).
If you’re pregnant or have recently delivered, consider speaking with a doctor about your carnitine levels. People who are pregnant have a higher risk of carnitine deficiency.
People who are taking certain types of antibiotics and anticonvulsants should speak with a doctor before taking L-carnitine, as this supplement may interact with the medications.
L-carnitine is an amino acid that may help support weight loss, brain function, and disease prevention.
It’s produced naturally in your body, but it’s also found in foods like meat and dairy products. Supplements may benefit those with lower levels, such as older adults, vegans, and vegetarians.
Consider speaking with a healthcare professional before taking L-carnitine. They could help you decide whether it’s appropriate and recommend the best dosage.