Carnitine is great for a number of conditions: it is a good energy booster, a powerful antioxidant, and a mood and cognitive enhancer. Read on to discover more about the health benefits of carnitine.

What is Carnitine?

Carnitine is an amino acid found in nearly every cell of the body. It is a generic name for a variety of compounds such as L-carnitine, acetyl-L-carnitine, and propionyl-L-carnitine. The three are chemically similar and some of their benefits overlap. However, they have some distinct mechanisms of action and uses.

  • Acetyl-L-carnitine is generally used to improve brain functioning and cognition [1].
  • L-carnitine is used to increase energy levels and physical performance [23].
  • Propionyl-L-carnitine is used to boost circulation [4].

All forms of carnitine play a vital role in the production of energy. Carnitine helps turn body fat into energy. It also gets rid of toxic compounds from the mitochondria to prevent their buildup. Carnitine is produced by the liver and kidneys and stored in muscle, brain, and heart tissue–all of which use fatty acids as energy [5].

You’ll get carnitine from meat, fish, poultry, and milk. People with genetic disorders, chronic diseases, and those on a vegetarian diet can often benefit from supplemental carnitine. The same is true for underweight and premature babies. Other conditions that cause carnitine deficiency include angina (chest pain) and intermittent claudication (cramping leg pain from blocked arteries) [6].



  • Helps mitochondrial and energy function
  • Supports liver function
  • Enhances brain function
  • Reduces brain and bodily fatigue
  • Improves performance
  • Increases semen quality and fertility in men


  • May contribute to heart disease by metabolizing TMAO
  • Can cause nausea or stomach upset
  • Long-term use may cause oxidative stress in the liver and blood
  • Inhibits thyroid function

Health Benefits of Carnitine

1-2) Aids Weight Loss and Enhances Performance

L-carnitine is often referred to as a weight loss aid. Since younger people have a sufficient amount of carnitine in the body it does not have as great of results as in older people. In older people, carnitine improves body composition. However, it may improve exercise endurance in all ages by increasing muscle carnitine levels [7].

Initial studies have found that dietary carnitine stimulates the break down of fats into energy, reduces the amount of lactic acid produced during exercise, speeds up recovery from exercise stress, prevents cell damage, and prevents cell death. This may contribute to weight loss [8].

In a study of overweight women diagnosed with polycystic ovary syndrome, carnitine supplements reduced their weight, body mass index, and waist and hip size (circumference) [9].

One study supplemented the diets of dialysis patients with 1,000 mg of carnitine for 12 weeks but found no changes in leptin levels, body weight, or body mass [10].

3) May Reduce Fatigue From Disease and Aging

Fatigue is common in cancer patients after treatments from chemotherapy, radiation therapy, and poor nutrition. Low carnitine levels can contribute to this fatigue.

Carnitine may help improve mood and quality of sleep while diminishing fatigue. In one study, terminal cancer patients received 250 milligrams of carnitine 3 times a day and as a result, improved fatigue and quality of life [11].

Patients with kidney disease often have anemia, a condition in which red blood cells are deformed. The deformity prevents the blood cells from carrying enough oxygen to the body’s tissues, causing fatigue. A study following dialysis patients found that carnitine supplements reduced red blood cell deformity and increased overall red blood cell count in 3 months [12].

Another study on dialysis patients found that carnitine injections helped sustain higher levels of oxygen use (improved endurance), such as during exercise, and also reduced overall fatigue [13].

In a study of elderly subjects, acetyl-L-carnitine treatment reduced physical and mental fatigue, reduced muscle pain, and improved cognitive function [14].

Feeding acetyl-l-carnitine and lipoic acid to old rats significantly improved metabolic function while decreasing oxidative stress [15].

4) May Improve Mood

Carnitine’s energy-boosting abilities may also serve to reduce depressive symptoms.

Initial studies found that acetyl-L-carnitine has an anti-depressant effect in elderly patients with age-associated depression [16].

A study found that supplementing the diets of fibromyalgia patients with acetyl-L-carnitine improved depressive symptoms and reduced muscle pain [17].

In a mouse model of depression, treatment with acetyl-L-carnitine improved the main symptoms [18].

5) May Improve Cognition

Carnitine levels gradually decline as Alzheimer’s progresses, suggesting that patients with Alzheimer’s could potentially benefit from acetyl-L-carnitine treatment [19].

L-carnitine, especially acetyl-L-carnitine improves memory in older people and in Alzheimer patients by slowing the progression of the disease [20].

By consuming carnitine, acetylcholine is produced. This neurotransmitter usually declines as memory loss advances. In this case, carnitine increases energy production and gives energy to starved brain cells which slow down memory loss [21].

In a rat model of chronic kidney disease, administration of carnitine significantly improved cognitive function [22].

6) May Help Male Infertility & Sexual Function

The amount of carnitine in semen is directly related to sperm count and mobility. Therefore, an intake of carnitine can help treat male infertility. Carnitine can provide more energy for sperm cells and can reduce cell death in the testes [23].

A study of 100 infertile men revealed that the intake of carnitine supplements increased motility in the sperm cells [24].

Infertile men with varicose veins in the scrotum (varicocele) took carnitine for 6 months (250 mg, 4x a day). Results showed increased sperm count, mobility, and concentration [25].

A build-up of free radicals can be caused by infection, long sexual abstinence, harmful environmental factors, and varicocele. These free radicals damage cell structure and genetic material, and accelerates cell death.

Since carnitine is an antioxidant and has a neutralizing effect on free radicals, it makes sense it may improve the viability of sperm cells. This was confirmed both in cells and in organisms [22].

A study of dialysis patients found that testosterone levels were directly correlated with carnitine levels in the blood, suggesting that supplemental carnitine may increase testosterone levels and sexual function [26].

However, a study on rats showed that inhibiting the production of carnitine (and consequently lowering the overall level of carnitine) did not decrease the sexual activity or sperm quality of male rats [22].

7) May Help Insulin Resistance

Insulin resistance may be related to an inability to burn fat. Increased levels of fat in lean tissue can be a sign of insulin resistance.

Research suggests that carnitine may improve insulin sensitivity by boosting fat oxidation in lean tissue and muscles [27].

In a study of overweight women with polycystic ovary syndrome, carnitine supplements lowered glucose and insulin blood levels, and reduced insulin resistance [9].

8) Sleep Quality

Sleep-disordered breathing is associated with heart damage and altered heart carnitine metabolism. Although carnitine levels are low in heart tissue in those with chronic heart failure, carnitine levels of the blood are increased because of leakage from damaged heart cells and altered carnitine metabolism [28].

Carnitine supplementation can help patients suffering from obstructive sleep apnea, a condition where breathing repeatedly stops and starts during sleep. Carnitine helped improve airway for breathing and improved overall sleep quality for patients [29].

In a study of elderly subjects, acetyl-L-carnitine treatment improved sleep quality [14].

However, a study of fibromyalgia patients found no improvement in sleep disturbances by L-carnitine [30].

9) May Improve Daytime Alertness in Narcolepsy

Acylcarnitine levels are abnormally low in narcolepsy patients. L-carnitine supplements may improve daytime alertness in these patients. L-carnitine treatment increased acylcarnitine and reduced blood lipids [30].

10) May Protect Against Heart Disease

Carnitine and its derivatives protect heart function and have demonstrated benefits in conditions where a weak heart fails to pump enough blood, glucose, and oxygen to the body’s tissues. Without enough blood and oxygen to meet the body’s needs, heart attack and stroke can occur.

Carnitine can help those with heart conditions by increasing glucose metabolism, increasing blood flow, correcting abnormal heart rhythms, and reducing toxicity [31].

A 3-year long study on patients with heart failure found that L-carnitine increased survival rates compared to those who did not receive the treatment [32].

Taurine and L-carnitine can work together to benefit heart health. In rat muscle cells, L-carnitine and taurine stopped the multiplication and hardening of muscle cells. This can prevent plaque formation or atherosclerosis and cut the risk of heart disease [33].

11) May Slow HIV Progression to AIDS

Because HIV patients develop complications such as muscle, fat, and nerve degeneration, they may benefit from carnitine which prevents cell death. In HIV positive individuals L-carnitine and acetyl-L-carnitine treatments increased CD4 counts, reduced cell death, prevented heart tissue damage, and reduced the number of triglycerides (fat) in the blood [34].

L-carnitine prevents the death of white blood cells, which would help fight HIV infection. Specifically, L-carnitine treatment increased the amount of CD4 and CD8 T-cells, which are particularly helpful in fighting the HIV retrovirus [35].

An initial study on patients HIV-associated fat tissue degeneration did not find any evidence for using L-carnitine to reverse the effects of fat tissue degeneration. This study found that L-carnitine lowered cholesterol levels in the blood, but not the levels of triglycerides [36].

12) May Improve Kidney Function

In a rat model of chronic kidney disease, administration of carnitine significantly improved kidney function. Carnitine lowered the levels of creatinine and BUN in the blood, reduced kidney tissue damage and abnormal kidney enlargement [22].

13) May Strengthen Bones

In a mouse model of osteoporosis, L-carnitine and isovaleryl-L-carnitine stimulated bone formation, improving bone turnover, bone density, bone size, and bone structure [37].

Another study found that dietary L-carnitine improved the bone mineral content and bone mineral density in a female mouse model of postmenopausal bone loss. Results indicate slowed bone loss and improved bone structure [38].

Carnitine promotes bone mineralization, in part by inhibiting thyroid hormone action [39].

14) May Suppress Seizures

In several mouse studies of drug-induced seizure, pre-treating the mice with L-carnitine successfully suppressed seizures. The more carnitine a mouse was given, the more strongly seizures were suppressed [4041].

15) May Help the Liver

Many studies have found that valproate and other anticonvulsant drugs reduce the body’s carnitine levels, resulting in liver damage. L-carnitine supplementation in such individuals may prevent or reduce the severity of liver damage [42].

A rat model of hyperthyroidism induced by L-thyroxine injections showed that L-carnitine has a dose-dependent protective effect against liver damage [43].

In brain issues (encephalopathy) caused by liver cirrhosis, carnitine was able to lower ammonia and improve brain function [44].

16) Prevents Hyperthyroidism

Hyperthyroidism can occur when thyroid hormone is overproduced. L-carnitine can reverse and prevent symptoms of hyperthyroidism [39].

L-carnitine inhibits both triiodothyronine (T3) and thyroxine (T4) entry into the cell nuclei. This is relevant because thyroid hormone action is mainly mediated by specific nuclear receptors.

In one randomized trial, 2 and 4 grams per day of L-carnitine reversed hyperthyroid symptoms. In another study, L-carnitine relieved a “thyroid storm” [45].

17) May Help ALS

L-carnitine suppresses the onset of neuromuscular degeneration and increases the lifespan of mice with familial amyotrophic lateral sclerosis (ALS) [46].

Side Effects & Precautions

Taking doses at about 3 grams per day can cause vomiting, diarrhea, a fishy body odor, abdominal cramps, and nausea. More severe and rarer side effects are seizures and muscle weakness for those who are prone to heart disease [11].

Some research suggests that carnitine is metabolized into TMAO, which changes cholesterol metabolism and may promote plaque build-up in the arteries. This leads to the degeneration of artery walls, restricted blood circulation, and blood clots. These conditions may cause stress to the heart, possibly leading to heart disease [47].

As mentioned, carnitine inhibits both triiodothyronine (T3) and thyroxine (T4) entry into the cell.  This means that if you’re hypothyroid, it’s not a great supplement to take.

Long-term use of L-carnitine accelerates the production of reactive oxygen species in the liver and blood in mice [48].

L-carnitine may disturb kidney function through ion transporters in mice [48].

Buy Carnitine

I find that Acetyl Carnitine has more noticeable effects, especially when it comes to the brain.

This section contains sponsored links, which means that we may receive a small percentage of profit from your purchase, while the price remains the same to you. The proceeds from your purchase support our research and work. Thank you for your support.

Click here to subscribe


1 Star2 Stars3 Stars4 Stars5 Stars
(24 votes, average: 4.42 out of 5)

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.