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What is L-carnitine, And How Does It Work?

L-carnitine is found in numerous supplements and energy drinks. The rationale behind taking L-carnitine is that it is thought to boost metabolism, help you lose weight, and enhance your athletic performance. 

As with all athletic supplements, we tend to get mixed messages about the benefits and safety of these things. Too much of our information comes from “folks” at the gym and not enough from established sources. This guide will give you the facts about L-carnitine

The word carnitine is derived from the Latin word for meat or flesh. L-carnitine is obviously a vital nutrient we get from meat. It is a naturally occurring chemical made by the kidneys from two amino acids. Technically, we do not require L-carnitine in our diets since it is synthesized in our bodies from other things. 

However, the natural benefits of L-carnitine can be increased by taking a supplement. The same natural processes our bodies are made to utilize when producing L-carnitine may be enhanced if we increase the amount of L-carnitine in our bodies. 

So far, research shows tremendous promise for L-carnitine supplements. Many people already see the benefits of taking L-carnitine as an exercise supplement. Increased stamina and faster recovery times are well known among people who take L-carnitine as an exercise supplement. 

But beyond exercise, scientists are finding that L-carnitine has a wealth of benefits. L-carnitine appears to help with everything from blood flow to brain function. 

This guide will give you the facts on L-carnitine. What exactly is L-carnitine? How does it work? What are the benefits of L-carnitine? And is L-carnitine safe?

What is L-carnitine

L-carnitine is a naturally occurring amino acid derivative. It is synthesized by our bodies using the amino acids lysine and methionine. We also require vitamin C for this synthesis to properly occur. 

Although our bodies produce sufficient amounts of L-carnitine, you can also get additional L-carnitine from meats and fish. Vegans and vegetarians may lack sufficient quantities of amino acids in their diets and therefore may need to get L-carnitine from a supplement. 

L-carnitine plays an important role in energy production in the body by transporting fatty acids to the mitochondria in cells. 

Mitochondria are the parts of cells that produce energy for metabolism and other functions. By burning the fatty acids, mitochondria generate energy for the body. 

Types of L-carnitine

The primary form of carnitine is L-carnitine. This is the chemical that is synthesized by our bodies and most common in meats and fish. It is also the most common form of carnitine in supplements. 

Yet, carnitine comes in serval forms. Like most naturally occurring chemicals, there are different formations of the same chemicals. 

Here are the various forms of carnitine:


This is an inactive form of carnitine that can cause deficiencies in your body. D-carnitine can inhibit the natural production of L-carnitine and make it impossible for your body to absorb other useful forms of carnitine. 


This is often called ALCAR. It is regarded as having the most benefits for the brains. Research demonstrates that ALCAR has benefits for people who suffer from neurodegenerative disorders. 


This form of carnitine is good for circulatory issues It shows promise in helping people with peripheral vascular disease and high blood pressure. Because propionyl-L-carnitine increases production of nitric oxide, it generally helps with blood flow issues. 

L-carnitine L-tartrate

This is the form used in sports supplements. It has a high absorption rate and can help with tired and sore muscles. 

The forms most often used in supplements are acetyl-L-carnitine and L-carnitine. They have the most widespread benefits for most people. However, check to see which form will best suit your needs and take the one the provides the most benefit. 

How does L-carnitine work?

The primary function of L-carnitine in the body is to assist in mitochondrial functions. The mitochondria are the cellular engines that produce energy. 

L-carnitine transports fatty acids into the mitochondria where it is converted through biochemical processes into energy. During periods in which the body is deprived of calories, for example, during exercise and dieting, L-carnitine helps with the biochemical mechanisms that transfer fatty acids from body tissue and transport these to cells to convert into energy. 

L-carnitine indirectly helps with brain function. Although brain tissue does not directly make use of L-carnitine and fatty acids, the increased oxidation that takes place in the chemical processes facilitated by L-carnitine boosts brain functions.

L-carnitine Benefits

The benefits of L-carnitine should be obvious. Cellular function, the production of energy, and enhanced brain function are the natural, baseline benefits of L-carnitine. As a supplement, though, L-carnitine can offer increased benefits for several reasons. 

Weight Loss

Since the basic function of L-carnitine is to take fatty acids from fatty tissue in the body, it logically follows that it offers benefits for weight loss when taken as a supplement. Increased L-carnitine levels mean increased use of fat for the production of energy rather.

One important study demonstrated that L-carnitine supplements can lead to significant weight loss, especially when combined with aerobic exercise. Over the course of a 42-day study, fat oxidation increased by as much as 62 percent in some subjects. 

Another study showed that individuals lost as much as three pounds in as little as a few days while taking L-carnitine supplements. These results were significantly high than people who took no supplements but underwent the same levels of exercise. This study showed that L-carnitine supplements were particularly effective for obese individuals. 

While the research can show mixed results, the overall picture of L-carnitine as a weight loss supplement is extremely promising. Much of the science demonstrates that L-carnitine supplements work well as a weight-loss supplement. 

Brain Function

L-carnitine shows tremendous promise in assisting brain function. 

Specifically, acetyl-L-carnitine (ALCAR) may help ward off the mental decline associated with age. It also helps improve one’s ability to learn. Studies have shown that ALCAR provides significant benefits for people who may be at risk for cognitive decline.  That ALCAR also enhances learning capacity is thought to be linked to the same mechanisms that preserve cognitive capacities. 

Still, further, another study showed that acetyl-L-carnitine can actually reverse some of the cognitive decline associated with Alzheimer’s disease and other diseases that reduce cognitive functions. Acetyl-L-carnitine can actually reverse dementia in some patients. 

Stemming from these studies, researchers have found that acetyl-L-carnitine provides significant benefits for people who have no cognitive decline and do not suffer from diseases of the brain. The same benefits that help people who are ravaged by problems that impact the brain can be extended to healthy people resulting in increased brain function. In fact, acetyl-L-carnitine can protect the brain from cell dame later in life. 

These cognitive benefits have also been found useful in treating alcoholism. One study showed that people with alcohol addiction showed significant improvement after taking a small dose of acetyl-L-carnitine supplements, and these improvements led to higher recovery rates. 

Exercise Supplement

L-carnitine is also widely regarded as an excellent supplement for exercise. L-carnitine appears to increase oxidation processes which enhance oxygen and blood flow. This produces some tangible results for exercise. These benefits include:


L-carnitine supplements can improve recovery from high-intensity training by speeding up the processes of rebuilding tissue. 

Oxygen supply to muscles

Because L-carnitine enhances oxidation at the cellular level, it tends to increase oxygen in the blood. Combined with the fact that L-carnitine specifically enhances the flow of blood overall, and we find that an L-carnitine supplement substantially increases the amount of oxygen that saturates muscles during exercise. 


The increase in blood flow and the enhanced nitric oxide output that come from L-carnitine supplements increase stamina. 

Muscle soreness

Again, increased blood flow and higher levels of oxygen tend to reduce the muscle soreness that comes from exercise. 

Red blood cell production

The natural effects of L-carnitine are increased with a supplement, and this leads to an increase in the production of red blood cells. An increase in red blood cells makes it possible to exercise more and opens the pathways to increased muscle protein synthesis. 

Researchers say that there is room for more study, but the results at this stage clearly show that L-carnitine supplements are beneficial for increased brain functions. 

Type 2 Diabetes

Some research shows that L-carnitine has benefits for people with type 2 diabetes. One study, in particular, demonstrated that people with type 2 diabetes who were already taking prescribed medications showed significantly reduced blood sugar levels after taking L-carnitine supplements. Researchers believe that L-carnitine helps produce an enzyme that aids in metabolizing carbohydrates. 

Food sources with L-carnitine

L-carnitine is produced in the body, and for most healthy people there is enough present to sufficiently perform body functions. However, we can always get more L-carnitine from food sources. Some of the best sources of L-carnitine include:


A 4-ounce steak contains between 56 and 160 milligrams of L-carnitine. 


1 cup of milk contains 8 milligrams. 

Chicken breast

4 ounces of cooked chicken breast contains 3 to 5 milligrams. 


A 2-ounce serving of cheese contains 2 milligrams. 

You can get L-carnitine from non-animal sources in whole wheat bread and asparagus. 

Adults who regularly eat meat generally get about 60 to 180 milligrams of L-carnitine per day through dietary sources. Vegetarians and vegans tend to get around 1-12 milligrams per day. 

The body absorbs between 50 and 80 percent of the L-carnitine taken in through dietary sources. 

L-carnitine Side Effects and Precautions

Since L-carnitine is a naturally occurring chemical, produced by the body and found in a variety of food sources, it is generally considered safe and has no real side effects or dangers. 

When taking L-carnitine supplements, experts generally say there are no real side effects or dangers for as much as a year if you are taking them as directed. 

Over time, some side effects can include nausea, vomiting, stomach upset, heartburn, and diarrhea. L-carnitine supplements can also cause urine, breath, and sweat to take on a “fishy” odor. 

Do not take D-carnitine and DL-carnitine. These can block the normal function of L-carnitine and produce the effects of L-carnitine deficiency. 

L-carnitine Dosage

For the standard form of L-carnitine, the normal dose is 500-2000 milligrams per day. 

For other forms of L-carnitine the doses are slightly different, and these dosages can depend on exactly why you are taking them. Here is a general overview:


For brain healthy and increased brain function the doses vary from 600- 2500 mg per day.

L-carnitine L-tartrate

This is used primarily for exercise performance. The doses are 1000-4000 mg per day. 


This is taken to improve blood flow and vascular health. It can also help with high blood pressure. The doses are generally 400-1000 mg per day. 

Over the long term, taking up 2000 mg per day of some form of L-carnitine is widely regarded as safe. 

Wrapping things up

L-carnitine is already widely known as a dietary supplement. People are taking L-carnitine as an exercise supplement, weight loss, increased blood flow and increased brain function. The scientific studies so far show that L-carnitine really does work for all these things.

We naturally produce L-carnitine in our bodies. It is made with a combination of simple amino acids. We also generally produce enough L-carnitine to stay healthy. A simple and healthy diet makes it possible to synthesize all the L-carnitine we need for normal functions. 

However, since L-carnitine works in ways that are specifically helpful for blood flow, oxidation, and burning fats, it is clearly useful to take supplemental L-carnitine for specific purposes. 

People who engage in regular high-intensity exercise can benefit from the boost to blood flow and oxidation that L-carnitine offers. An L-carnitine supplement helps enhance stamina and reduce muscle tiredness and soreness. 

Still, further, L-carnitine supplements have been scientifically proven to help with weight loss, especially for people struggling with obesity. It has real benefits for people who are suffering from cognitive decline. And L-carnitine can also provide real benefits for people with vascular disease and blood flow problems. 


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