Acetyl-L-Carnitine: Nootropic Spotlight

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About the Author

Ben was awarded a Master of Science in Regenerative Medicine from Imperial College London. He is currently completing a PhD at Imperial. 

 

Contents

• What is Acetyl-L-Carnitine?
• Acetyl-L-Carnitine Deficiency
• Acetyl-L-Carnitine Benefits
• Acetyl-L-Carnitine Mechanism of Action
• Acetyl-L-Carnitine Side Effects

 

Acetyl-L-Carnitine: A Health Guide to Safe and Effective Supplementation

  

 

What is Acetyl-L-Carnitine?

Acetyl-L-Carnitine, or ALCAR for short, is the acetylated form of carnitine. This difference enables the two substances to carry out different roles within the body. It is relatively easy for the body to change one form to the other¹.

ALCAR can be produced by the brain, liver and kidneys, so it is not a dietary requirement, but supplementation can prove advantageous¹.

 

Acetyl-L-Carnitine Deficiency

Due to its natural occurrence in the body, deficiency generally only occurs one of two ways²:

• Primary deficiency – a gene abnormality makes it difficult for cells to take in carnitine from the blood.
• Secondary deficiency – health problems, such as liver disease or digestive issues, lower the amount of carnitine in the blood.

Symptoms can include²:

• Muscle weakness
• Fatigue
• Irritability
• Low blood sugar levels
• Shortness of breath

 

 

Acetyl-L-Carnitine Benefits

Despite the fact that it can be produced by the body, there are a number of benefits which are associated with adding more acetyl-L-carnitine to your nutritional intake:

• Mood boosting: studies have shown a link between depression and acetyl-L-carnitine levels. Supplementation was found to not only reduce the symptoms of depression, but work as effectively as some anti-depressant medication – minus the side effects!^3,4
• Brain boosting: ALCAR supplementation has been shown to increase cognitive functioning of the brain⁵
• Pain reducing: studies have shown that ALCAR can reduce pain induced by peripheral neuropathy, damage to the nerves which send signals your extremities^6–8

 

Acetyl-L-Carnitine Mechanism of Action

Acetyl-L-carnitine has several functions throughout the body, but it is not yet entirely clear why it exhibits some of these beneficial effects. Research has, however, shown the following:

• Supplementation increased the concentration of noradrenaline in the hippocampus and serotonin in the cortex. These two neurotransmitters have been linked to depression, and are often used in antidepressant medication^9,10
• Cognitive functions, such as memory and learning capacity, are known to decline with age. ALCAR has been shown to counter these effects by improving synaptic function in the brain, the means by which nerves communicate⁵
• ALCAR acts as antinociceptive, reducing pain that originates from sensory neurons. It begins a multistep process which reduces the release of glutamate from the primary afferents in the spinal cord, the neurons which transmit pain signals^11,12

 

Acetyl-L-Carnitine Side Effects

Acetyl-L-carnitine is generally safe, unless consumed in very high doses. In such a case, side effects may include:

• Nausea
• Vomiting
• Abdominal cramping
• Diarrhoea
• Body odour

  

Evidence

1. Mendelson SD. NUTRITIONAL SUPPLEMENTS AND METABOLIC SYNDROME. Metab Syndr Psychiatr Illn. 2008 Jan 1;141–86.
2. Carnitine Deficiency | Cedars-Sinai [Internet]. [cited 2022 Jun 15]. Available from: https://www.cedars-sinai.org/health-library/diseases-and-conditions/w/what-is-carnitine-deficiency.html
3. Nasca C, Bigio B, Lee FS, Young SP, Kautz MM, Albright A, et al. Acetyl-L-carnitine deficiency in patients with major depressive disorder. Proc Natl Acad Sci U S A. 2018 Aug 21;115(34):8627–32.
4. Veronese N, Stubbs B, Solmi M, Ajnakina O, Carvalho AF, Maggi S. Acetyl-l-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis. Psychosom Med. 2018 Feb 1;80(2):154–9.
5. Kobayashi S, Iwamoto M, Kon K, Waki H, Ando S, Tanaka Y. Acetyl-l-carnitine improves aged brain function. Geriatr Gerontol Int. 2010 Jul;10(SUPPL. 1):S99–106.
6. Li S, Li Q, Li Y, Li L, Tian H, Sun X. Acetyl-L-Carnitine in the Treatment of Peripheral Neuropathic Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS One. 2015 Mar 9;10(3):e0119479.
7. Veronese N, Sergi G, Stubbs B, Bourdel-Marchasson I, Tessier D, Sieber C, et al. Effect of acetyl-l-carnitine in the treatment of diabetic peripheral neuropathy: A systematic review and meta-analysis. Eur Geriatr Med. 2017 Apr 1;8(2):117–22.
8. Di Stefano G, Di Lionardo A, Galosi E, Truini A, Cruccu G. Acetyl-L-carnitine in painful peripheral neuropathy: a systematic review. J Pain Res. 2019;12:1341.
9. Smeland OB, Meisingset TW, Borges K, Sonnewald U. Chronic acetyl-l-carnitine alters brain energy metabolism and increases noradrenaline and serotonin content in healthy mice. Neurochem Int. 2012 Jul 1;61(1):100–7.
10. SNRIs | Prescribing information | Depression | CKS | NICE [Internet]. [cited 2022 Jun 15]. Available from: https://cks.nice.org.uk/topics/depression/prescribing-information/snris/
11. Truini A, Piroso S, Pasquale E, Notartomaso S, Stefano G Di, Lattanzi R, et al. N-acetyl-cysteine, a drug that enhances the endogenous activation of group-II metabotropic glutamate receptors, inhibits nociceptive transmission in humans. Mol Pain. 2015 Mar 20;11.
12. Notartomaso S, Mascio G, Bernabucci M, Zappulla C, Scarselli P, Cannella M, et al. Analgesia induced by the epigenetic drug, L-acetylcarnitine, outlasts the end of treatment in mouse models of chronic inflammatory and neuropathic pain. Mol Pain. 2017;13.