Carnitine or L-carnitine is a naturally occurring amino acid in the human body that aids in energy production by converting fats into energy. Carnitine helps transport fatty acids into the mitochondria, which are responsible for producing energy in every cell of the body.


Acetyl-Carnitine or L-Carnitine is used for infertility problems, especially male infertility and sperm health, as well as for memory and neurological problems. Additionally, carnitine is used for disorders related to alcoholism and Parkinson’s disease.


Types of Carnitine


There are several types of carnitine which are classified according to their activity in the body, into active and inactive:


  • D-Carnitine: prevents the absorption of other types of carnitine, therefore it is not considered a nutritional supplement.
  • Acetyl-L-carnitine: effective in protecting the brain from neurological diseases in addition to maintaining human body health and energy production.
  • Propionyl-L-carnitine: effective in lowering blood pressure. It helps in the production of nitric oxide which dilates the blood vessels leading to increased blood flow and lowering of blood pressure.
  • L-carnitine: added to other supplements, specifically those related to athletic performance. It aids in boosting athletes’ energy and maintaining muscle health.


Mechanism of Action of Carnitine


L-Carnitine transports fatty acids into the mitochondria, which is the cell’s energy powerhouse to be oxidized for energy production.


Benefits of L-Carnitine and Acetyl-L-Carnitine


  • Carnitine & Sterility


Studies have shown that taking L-carnitine in men increases levels of testosterone leading to improved sexual function. This is especially beneficial as men age and testosterone levels drop.


It was also observed that taking L-carnitine increases sperm count and motility leading to a higher chance of conception. L-carnitine also helps relieve symptoms of Peyronie disease, which causes bending of a man’s penis.


  • Carnitine & Memory


Carnitine helps improve overall memory and brain function. It also protects brain cells from damage. Studies have shown that carnitine reduces memory loss accompanying old age.


  • Carnitine for Alzheimer’s


Carnitine slows the progression of Alzheimer’s disease, as it supports healthy brain function and memory, especially in younger patients, who generally have a faster rate of disease progression.


  • L-Carnitine for Nerves


Studies have shown that taking carnitine supplements significantly improves symptoms associated with nerve damage and pain, such as diabetic neuropathy. Other studies have shown the role of carnitine in relieving the symptoms of Sciatica, which causes pain in the lower back that spreads to the hip, buttocks, and entire leg.


Although carnitine supplements relieve neuropathic pain and it’s symptoms, they may increase nerve pain resulting from chemotherapy given to cancer patients. Therefore, it is advised to avoid carnitine in cases of cancer and chemotherapy.


  • L-Carnitine to Enhance Athletic Performance


Studies conducted have shown the apparent effect of carnitine in increasing athletic endurance and performance. Since carnitine is stored in skeletal muscles, it helps by enhancing energy production in the cells’ mitochondria which directly gives muscles an energy boost while training.


Taking carnitine may assist in:

  • Recovery: L-carnitine supplements speed up muscle recovery from injuries by supplying the muscles with oxygen to break down lactic acid.
  • Endurance: L-carnitine supplements may increase muscle perfusion as well as the production of nitric oxide, which helps increase endurance and reduce fatigue.
  • Muscle pain relief: especially after exercise.
  • Increasing red blood cell production: Some studies indicate that L-carnitine helps increase the production of red blood cells (erythropoiesis), which transport oxygen to the muscles.


  • Carnitine & Alcohol


Due to the severity and difficulty of alcohol withdrawal symptoms that usually appear within the first week after cessation of alcohol consumption, some addicts cannot tolerate them leading to relapse. L-Carnitine greatly reduces alcohol withdrawal symptoms, especially when injected into the blood.


Some benefits of L-Carnitine still being studied:


  • ADHD (Attention Deficit Hyperactivity Disorder)
  • Diabetes
  • Hypertension
  • Hypercholesterolemia and hyperlipidemia
  • Reducing fatigue in multiple sclerosis patients
  • Schizophrenia
  • Cataracts
  • Down’s syndrome


Side Effects of Carnitine


Generally, taking L-Carnitine and Acetyl-Carnitine is safe, however there are some cases in which these supplements should be avoided.


  • Carnitine for Pregnant & Breastfeeding Women


There is insufficient data on pregnant or breastfeeding women taking L-Carnitine; Therefore, it is advised against taking L-Carnitine during pregnancy and breastfeeding.


  • Carnitine & Children


It is safe for children to take L-Carnitine and no unpleasant symptoms have been reported in such cases.


  • Carnitine & Bipolar Disorder


Taking L-Carnitine in bipolar patients may exacerbate the symptoms of this disease, especially during periods of remission.


  • Carnitine & Chemotherapy-Related Nerve Pain


Although carnitine relieves nerve damage symptoms and pain, it may increase nerve pain caused by chemotherapy in people with cancer.


  • Carnitine & Hypothyroidism


Some studies available warn against the intake of L-Carnitine in patients with hypothyroidism, as L-Carnitine may interfere with thyroid hormones.


  • Carnitine & Seizures


An increase in the number and severity of seizures has been observed in people with nervous system disorders who took L-carnitine. Therefore, these supplements should be avoided by all people who suffer from nerve spasms.


Carnitine Drug Interactions


  • Carnitine & Acenocoumarol (Sintrom)


Acenocoumarol is an anticoagulant that slows down the process of blood clotting. Taking carnitine with acenocoumarol may increase the effectiveness of this medication and prolong its effect. This exaggerated effect leads to internal bleeding or the appearance of bruises under the skin. Therefore, this combination should strictly be avoided.


  • Carnitine & Warfarin


Warfarin is also an anticoagulant that slows down the process of blood clotting. Carnitine prolongs the effect of warfarin in the body and this may lead to bleeding or bruising under the skin. Consult your doctor before starting L-carnitine if you are taking warfarin as dosage adjustment might be necessary.