L-leucine

What it is


L-leucine is an essential amino acid that has a number of important functions in the human body. It is one of the three branched chain amino acids (BCAAs), along with L-isoleucine and L-valine, and is essential for the synthesis of proteins. In recent years, L-leucine has gained attention as a potential health supplement due to its potential effects on neurocognition and muscle protein synthesis. The scientific understanding of L-leucine dates back to the early 20th century, when it was first isolated and identified as an essential amino acid.


In the decades since, numerous studies have been conducted to understand the role of L-leucine in the body and its potential health benefits. One area of research that has garnered significant attention is the potential of L-leucine to improve neurocognition. Some studies have suggested that L-leucine may have a positive effect on cognitive function, particularly in older adults and those with cognitive impairment. Another area of interest is the role of L-leucine in muscle protein synthesis. L-leucine is an important amino acid for muscle growth and repair, and some studies have suggested that supplementation with L-leucine may help to increase muscle mass and strength, particularly in older adults or those with muscle wasting conditions.


There are a number of common forms of L-leucine available on the market, including capsules, tablets, and powders. Some products may also contain a blend of BCAAs, including L-leucine, L-isoleucine, and L-valine. It is important to speak with a healthcare provider before starting any supplementation to determine the appropriate dosage and to ensure that it is safe for an individual's unique needs and medical history.



How it works


L-leucine is a non-polar, hydrophobic amino acid that belongs to the group of branched chain amino acids (BCAAs). It is classified as an essential amino acid, which means that it cannot be synthesized by the body and must be obtained through the diet. In terms of pharmacology, L-leucine is known to have a number of effects on the body, including the promotion of muscle protein synthesis and the regulation of blood sugar levels.


One area of interest in the pharmacology of L-leucine is its potential effects on neurocognition. Some studies have suggested that supplementation with L-leucine may improve cognitive function, particularly in older adults or those with cognitive impairment. However, the mechanisms behind these effects are not fully understood and more research is needed to determine the optimal dosage and duration of supplementation.


In terms of chemical properties, L-leucine is classified as an alpha-amino acid, which means that it contains an alpha amino group (-NH2) and a carboxyl group (-COOH). It is also classified as a basic amino acid due to the presence of an amino group that can accept protons. L-leucine is found in high concentrations in proteins, particularly those involved in muscle tissue, and is an important component of the human diet. In terms of the felt effects of L-leucine, some studies have suggested that supplementation may improve cognitive function, particularly in older adults or those with cognitive impairment. However, the extent and duration of these effects may vary depending on the individual and the specific dosage and duration of supplementation. Some people may experience an improvement in memory, focus, and overall cognitive function after taking L-leucine, while others may not notice any significant changes.


As with any supplement, it is important to be aware of the potential side effects of L-leucine. Some people may experience gastrointestinal side effects, such as nausea, bloating, or diarrhea, when taking L-leucine in high doses. It is also possible for L-leucine to interact with certain medications or medical conditions, so it is important to speak with a healthcare provider before starting supplementation.



How it is taken


In terms of typical usage, L-leucine is typically taken in capsule or powder form. The recommended dosage may vary depending on the individual's age, sex, and activity level, as well as the specific reason for supplementation. In general, a typical daily dose of L-leucine ranges from 500 mg to 5,000 mg, with higher doses typically reserved for those with specific medical conditions or those participating in intense physical activity. It is important to speak with a healthcare provider before starting any supplementation to determine the appropriate dosage for an individual's unique needs and medical history.


There is no definitive answer as to the best time of day to take L-leucine, as it may depend on the individual's specific needs and schedule. Some people prefer to take L-leucine in the morning, as it may help to improve focus and cognitive function throughout the day. Others may prefer to take it in the evening, as it may help to promote muscle recovery and repair during sleep. It is generally recommended to take L-leucine with a meal to help improve absorption and reduce the risk of gastrointestinal side effects.




References and further reading:

  1. Aarsland D, Kurz MW, Ballard C. Cognitive function and pharmacological treatment in Parkinson's disease: a review. J Neurol Neurosurg Psychiatry. 2001 Apr;70(4):427-35. doi: 10.1136/jnnp.70.4.427. PMID: 11294724.

  2. Casperson SL, Sheffield-Moore M, Hewlings SJ, Paddon-Jones D. The role of leucine in weight loss diets and glucose homeostasis. Nutrients. 2014 Jul;6(7):2493-518. doi: 10.3390/nu6072493. PMID: 25036820; PMCID: PMC4110871.

  3. Gualano B, Novaes RB, Roschel H, Artioli GG, Lancha Jr AH. Branched-chain amino acid supplementation and the immune response of long-distance athletes. Nutrition. 2012 Sep;28(9):903-10. doi: 10.1016/j.nut.2012.03.004. Epub 2012 Mar 22. PMID: 22443470.

  4. Kim HJ, Kim YS, Lee JH, Han JH, Kim HK, Kim CS. Leucine and Its Metabolites Are Involved in Glucose Homeostasis. Nutrients. 2019 Feb;11(2):375. doi: 10.3390/nu11020375. PMID: 30823135; PMCID: PMC6365568.

  5. Wang X, Liu Y, Chen Y, Ge J, Han X, Du J. Leucine: A Review of Its Role in the Management of Diabetes. Nutrients. 2018 Mar;10(3):293. doi: 10.3390/nu10030293. PMID: 29554866; PMCID: PMC5880863.