L-carnitine is a naturally occurring amino acid derivative that performs some important functions in the human body. This substance is also called vitamin-like, but it is not a vitamin, because the body can produce it on its own. The level of L-carnitine in the human body is homeostatic, which means that any excess is successfully eliminated by the body. Is it necessary to take L-carnitine additionally as a dietary supplement? Scientists have not firmly proven a direct fat-burning effect from supplementing in healthy, well-fed people, although it has clearer value in certain medical and dietary situations.
L-carnitine was discovered in 1905, but its physiological role was studied only by 1962. It turned out that this substance transports fatty acids to mitochondria through the inner membrane. In humans, it is present mainly in the muscles and the liver, and the body makes it from the amino acids lysine and methionine.
What is L-carnitine?
L-carnitine is the biologically active form of carnitine, the only form the body can use. It is concentrated in tissues that rely heavily on fat for fuel, such as skeletal muscle and the heart. Supplements come in several variants, including L-carnitine L-tartrate, which is popular with athletes, and acetyl-L-carnitine, which crosses into the brain more readily and is studied for cognitive uses.
L-carnitine action
Inside the muscle cells, there are microscopic bodies, which in science are called mitochondria. So, they are the generators of energy. The internal processes of mitochondria are similar to a stove, which will give more heat if you throw more fuel into it. In our body, in the role of fuel for these stoves act the same fats. And so, strictly speaking, that is what is burned.
As for the lives of athletes, the work of mitochondria is doubly important. After all, they give us energy by burning fat molecules. And the more energy we get, the better the results we show in training.
But where does L-carnitine fit in? This is where it gets interesting. Its job in this process is to deliver fat into the mitochondria. The more of these supplies that arrive, the more strongly the stove burns, the more energy we receive and the more fat we can use. Without enough carnitine, long-chain fatty acids cannot cross the mitochondrial membrane to be burned.
The main effects of L-carnitine:
- Fat burning support
- Increased intellectual and physical tone
- Increase stress tolerance
- Excretion of toxins and other harmful substances
- Lowering cholesterol
- Cardiovascular protection
Other beneficial effects of L-carnitine:
- Stimulates tissue regeneration
- Protects the nervous system
- Enhances oxygen supply to body tissues.
- Neutralizes the damaging effects of free radicals.
- Prevents apoptosis (cell death)
- Protects bones from osteoporosis
The benefits of L-carnitine for an athlete
L-carnitine increases the body’s endurance during aerobic sports (jogging, rowing, swimming, etc.). At the same time, if simultaneous weight loss is not required, the combination of L-carnitine with a high-fat diet will give the maximum energy effect.
L-carnitine is useful for increasing endurance and in anaerobic sports (bodybuilding, powerlifting, etc.). However, in this case, note that any apparent anabolic effect of L-carnitine may be masked by a decrease in total body weight due to a reduction in adipose tissue. Therefore, the effect of carnitine should be evaluated by calculating the percentage of adipose tissue relative to total body weight. At the same time, in order to maximize the effect of L-carnitine, it should be combined with a balanced diet and training. Some research also points to a useful role in recovery, with supplementation linked to less muscle soreness and damage after hard exercise.
Who should take L-carnitine?
L-carnitine is most relevant to endurance athletes looking to support fat use during long sessions, to people on a calorie-controlled diet who want to make the most of their training, and to older adults, whose natural carnitine levels tend to fall with age. Strict vegetarians and vegans, who eat little of the meat and dairy that supply carnitine, may also have lower stores. It is not a shortcut for weight loss on its own; without a calorie deficit and training, it does little.
Sources of L-carnitine
A large amount of this substance is found in fish, meat and dairy products. To meet the daily need you would have to eat around 300 to 400 grams of beef. In addition, any heat treatment significantly reduces the amount of L-carnitine in food. For this reason, it is sometimes taken in the form of a food supplement. There are quite a lot of similar products on the sports nutrition market, so it will not be difficult to find one.
Compatibility with other nutritional supplements
L-carnitine combines well with all fat burners, enhancing their positive effects and reducing possible side effects. In addition, carnitine can be combined with the intake of proteins and gainers during a period of gaining muscle mass. This can help you gain better-quality mass with less excess fat.
How much to take and when?
The optimal dosage of L-carnitine is a dose of 500 mg to 2 grams per day. Scientists have found that exceeding these doses leads neither to extra benefit nor, generally, to negative effects. It should be taken about 30 minutes before a workout and in the morning on an empty stomach. It is during these periods that L-carnitine has maximum activity. Because muscle stores build slowly, consistent daily use over several weeks matters more than any single dose.
Safety and side effects
For healthy adults, L-carnitine is generally well tolerated at the doses above. The most common complaints are mild and digestive, such as nausea or stomach upset, and very high doses can cause a fishy body odour. People with kidney disease, those on thyroid medication or seizure medication, and pregnant or breastfeeding women should speak to a doctor before using it.
Forms and how to choose
L-carnitine is sold in several forms, and the right one depends on your goal. Plain L-carnitine and L-carnitine L-tartrate are the usual choice for training and recovery, often as a powder or capsule. Acetyl-L-carnitine is favoured when the aim is mental focus, since it crosses into the brain more readily. Liquid versions are convenient and absorb quickly. Whichever you choose, take it with a meal that contains carbohydrate, since the insulin response helps the muscle take up and hold on to carnitine, and look for a product from a reputable brand with clear labelling of the dose per serving.
Frequently asked questions
Does L-carnitine really burn fat?
It enables fat to be transported into cells for burning, but it does not force the body to lose fat on its own. Results depend on training and a calorie deficit; carnitine supports the process rather than replacing it.
When is the best time to take it?
Common timing is in the morning and before exercise, ideally with a meal that contains some carbohydrate, which appears to help the muscle take up and retain carnitine.
Is L-carnitine safe for daily use?
For healthy people, daily doses within the recommended range are considered safe. Anyone with a medical condition or taking medication should check with a doctor first.