What is Carnitine? – Definition, Benefits, Side Effects,

Carnitine is a naturally occurring amino acid that you can also get from your diet. The primary function of this compound is to produce energy.

It also helps in maintaining the general wellbeing of your brain and lowering the risk of several disorders.

Consuming too much of this substance can produce counterproductive effects (more on that later).

In this article, we will cover everything you need to know about carnitine, including how it benefits your body, where to get it, and some potential side effects. But first, let us start by defining what carnitine is.

What is Carnitine?

Carnitine is a compound that your body produces naturally in small amounts. You can also get it from dietary intake or supplements.

By transporting fatty acids to the mitochondria (i.e., the powerhouse of the cell), carnitine helps with producing energy. There, the fats get metabolized to produce usable energy. When the body is trying to synthesize carnitine, it uses two amino acids known as lysine and methionine.

However, most people are unaware that the production of carnitine requires sufficient amounts of vitamin C.

You can get small amounts by consuming animal products (e.g., meat, fish).

Unsurprisingly, vegans and people with certain genetic disorders may have low levels of carnitine, which could negatively impact their general health.

Different Types

The biologically active form of carnitine is L-carnitine – this is generally the form available in the body, food, and supplements.

Other types of carnitine include:

  • D-carnitine – this is the inactive form that could lead to carnitine deficiency, by inhibiting the absorption of active forms.
  • Acetyl-L-carnitine (ALCAR)studies found that this form of carnitine may be the most effective for brain health. In fact, preliminary research suggests that ALCAR lowers the risk of some neurodegenerative disorders.
  • Propionyl-L-carnitine – most helpful for cardiovascular diseases, propionyl–L–carnitine boosts the production of nitric oxide (NO), which is essential for vasodilation (i.e., expansion of blood vessel diameter).
  • L-carnitine L-tartrate – you will most like find this form of carnitine in sports supplements because of its rapid absorption. Potential benefits of L-carnitine L-tartrate include the reduction of muscle soreness and acceleration of recovery after exercise.

Role in Your Body

The main role of L-carnitine is to optimize the function of the cell’s powerhouse. The vast majority of carnitine stores (98%) reside within your muscles. The remaining amount is usually found in the liver and blood circulation.

Some evidence even suggests that L-carnitine may be an effective anti-aging element.

The good news is that the available research showed that different forms of carnitine have different functions in the body. Therefore, if an individual wants to optimize their brain function, he/she can take ALCAR instead of a random type of carnitine.

The Benefits of Carnitine

Besides producing energy, carnitine may be helpful in getting rid of cellular waste, which prevents programmed death (i.e., apoptosis).

The following sections will detail the expected benefits of taking carnitine supplements:

Promotes Cardiovascular Health

L-carnitine can help with cardiovascular health.

Supplementing yourself with L-carnitine may improve the symptoms of heart failure (e.g., arrhythmias, chest pain).

According to some studies, carnitine may also be able to lower blood pressure and inflammation in the body.

One study found that 2 grams of acetyl-L-carnitine lowered systolic blood pressure (the top number of a blood pressure reading) by 10 points.

Patients with severe forms of heart disease, such as chronic heart failure and coronary artery disease, may also benefit from taking carnitine.

May Aid in Cancer Treatment

Cancer patients often have to undergo a long, exhausting process of chemotherapy, which increases their risk of carnitine deficiency. If this is the case for you, taking L-carnitine supplements will help with the symptoms of weakness and lethargy.

Interestingly, there is some early research that inspects the potential use of carnitine in preventing the tissue damage caused by chemotherapy.

Could Promote Weight Loss

Since L-carnitine drives fatty acids to the mitochondria for energy production, it makes sense that supplementing your body can lead to weight loss.

However, the complexity of the human body may interfere with this process. After all, not all results reported on animal subjects apply to human beings.

In one study that included 38 women who exercised 4 times per week, researchers found no evidence that supports the weight loss effects of carnitine.

However, other studies suggest a slight drop in body weight after taking L-carnitine supplements.

For instance, one review included 9 clinical trials and concluded that there is some evidence to support this theory. On average, participants who took carnitine supplements lost 1.3 kilograms more than those who did not.

Effects on Brain Function

L-carnitine may be useful for optimizing brain function.

Several animal studies found that ALCAR is beneficial in preventing age-related cognitive decline while improving learning skills.

When scientists inspected these effects on human subjects, they found that ALCAR helps in maintaining cognitive function in patients with Alzheimer’s disease and other neurodegenerative illnesses. For individuals without Alzheimer’s disease, carnitine exhibited optimized brain function.

Some people claim that carnitine may even protect the brain from inflicting damage caused by oxidative stress.

In one study, people who suffer from alcohol addiction took 2 g of ALCAR per day. Most participants experienced substantial improvement in all aspects of their brain function.

Exercise Performance

There is conflicting evidence surrounding the effectiveness of carnitine in optimizing physical performance.

Interestingly, researchers believe that some benefits of carnitine supplements may take weeks or months before becoming clinically relevant.

Here are the aspects where L-carnitine may be beneficial:

  • Recovery from exercise – L-carnitine may accelerate your recovery after strenuous physical activity. It can also help prevent DOMS, which is delayed-onset muscle soreness.
  • Muscle oxygen supply – oxygen is indispensable for the function of your muscles. By expanding the blood vessels that bring oxygen and nutrients to the muscles, carnitine may help athletes and gym-goers.
  • Stamina – the same action of improving blood flow throughout the body can reduce the threshold of fatigue and increase your stamina.
  • Red blood cell productionsome research suggests that carnitine may be able to boost the action of a hormone known as erythropoietin, which stimulates the bone marrow to produce more red blood cells.

May Regulate Blood Sugar Levels

L-carnitine may improve the symptoms of high blood sugar and the risk factors it poses.

In one study, scientists noted a significant drop in blood sugar in patients with type II diabetes after taking carnitine supplements. The placebo group did not experience this drop.

The authors of the study reported that carnitine increases the levels of an enzyme known as AMPK, which optimizes the use of carbohydrates in the body.

May Help with Hair Loss

Scientists are researching the effects of topical carnitine on hair growth. This amino acid promotes cellular proliferation and prevents apoptosis, which is optimal for hair growth.

In a study published by the Journal of Dermatological Science, scientists conducted a double-blind, randomized, placebo-controlled clinical trial on subjects with hair loss. The study involved the topical application of Carnitine Tartrate (CT) for 6 months (twice a day).

Scientists recruited 60 healthy participants with androgenetic alopecia, then divided them into two groups:

  • The first group received a 2% solution of CT
  • The second group received a placebo

After analyzing the results, the vast majority of participants reported a significant hair growth, which was objectified using the triclosan technique.

The authors of the study stated that “In this perspective, double-blind, randomized, placebo-controlled observational study, topical treatment of volunteers with moderate-level androgenetic alopecia with a 2% CT solution increased the total amount of scalp hairs after a period of 6 months. This study requires more experiments with a larger pool and a longer period of time.”


Sources – Where To Get Carnitine

Foods that contain decent amounts of carnitine include animal products, poultry, meat, and dairy. Red meat has the highest amounts of this substance.

To get sufficient amounts of carnitine, consume the following food elements:

  • Beefsteak (4 ounces) – contains 56 to 162 milligrams (mg)
  • Milk (1 cup) – contains 8 mg
  • Chicken breast (4 ounces) – contains 3 to 5 mg
  • Cheese (2 ounces) – contains 2 mg

If you are vegan, you could get some carnitine by consuming whole-wheat bread or asparagus.

Researchers found that adults who consume high amounts of red meat get between 60 and 180 mg of carnitine per day. Contrast that with the 10–12 mg that a vegan would get from their diet.

As for the absorption of this compound, research suggests that the intestinal walls are able to absorb 55–85% of dietary carnitine. The percentage drops substantially when carnitine is taken as a supplement (14–18%).

The Side Effects of Carnitine

When the dosage of carnitine is below 2 grams per day, most people experience no side effects. One study followed participants who daily took 3 grams of carnitine for 21 days. No side effects were reported.

Another review evaluated the effects of L-carnitine (2 grams per day) in the long term. Aside from mild side effects, such as nausea and bloating, participants did not develop any serious damage.

Theoretically, consuming L-carnitine for a long time can increase your levels of a compound known as trimethylamine-N-oxide (TMAO). Scientists found that high levels of TMAO increase the risk of plaque formation in the blood vessels (i.e., atherosclerosis). As a result, you could be more likely to develop heart disease, stroke, and peripheral artery disease.

With that said, more studies are necessary to determine the long-term side effects of this supplement and the toxic dosage.

The Appropriate Dosage Of Carnitine

Depending on the reason you are taking carnitine, the appropriate dosage may vary.

The following scenarios will describe the ultimate goal behind taking carnitine supplements.

Healthy adults

According to the National Institutes of Health (NIH), the liver and kidneys of healthy adults are capable of producing enough carnitine.

Additionally, the kidneys are able to store some carnitine, which makes blood concentration stable for some time, even if you consume foods that contain no carnitine. Finally, the kidneys will clear the excess carnitine through urine if you consume too much of this compound.

Therefore, supplementation may not be necessary.


Unlike regular people, athletes may need to take L-carnitine supplementation to optimize their performance. While this is not always necessary, many athletes report improved physical features after taking L-carnitine.

In theory, carnitine stops the catabolism (i.e., breakdown) of muscle tissue, which aids athletes during high-intensity exercises.

However, a recent study published in Molecules states that there isn’t enough evidence to support this effect. Therefore, we still don’t know whether carnitine supplements are necessary for athletes or not.

People Who Want to Lose Weight

Since L-carnitine aids in burning fats to produce energy, people claim that it can help people lose weight.

To optimize the action of carnitine, you need to follow healthy lifestyle habits, such as eating a balanced diet and exercising on a regular basis.

Dosage recommendations

If you want to take L-carnitine supplementation, it would be optimal to speak with your doctor first. In many cases, your doctor will suggest several methods to compensate for any potential nutritional deficiencies.

Moreover, many of the supplements that we consume irregularly can interfere with the action of vital medications (e.g., antihypertensive drugs, cholesterol drugs).

With all of that said, consuming 1–3 grams of carnitine per day is generally tolerable by most people. If you have any genetic disorder that interferes with metabolizing different compounds, speaking with your doctor is a must before taking carnitine supplements.


Carnitine is a necessary compound to produce energy in the cell by burning fatty acids. The supplementation of this substance may be useful for some people; however, the appropriate dosage varies, depending on your goals.

We hope that this article answered all the questions you had about carnitine and its effects on the human body.

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