What is Leucine?

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What is leucine?

Leucine is a tiny amino acid that plays a large role in multiple metabolic functions. Our previous blog detailed how amino acids are the “building blocks of protein” with multiple amino acids bonding together to form one protein molecule. Amino acids can be classified as being either non-essential or essential.  Leucine is considered one of nine essential amino acids, meaning that the body is not able to naturally produce leucine.  Thus, in order for us to satisfy our daily leucine needs, we need to consume it in the form of foods and drinks.  Leucine also belongs to a particular subset of essential amino acids called branched chain amino acids (BCAAs). 

The BCAAs have special properties that allow them to be integral components of multiple bodily functions.  They account for approximately 50% of muscle protein, as well as play a role in metabolic functions, protein synthesis, energy production, neurotransmitter production, glucose metabolism, immune responses, insulin sensitivity, liver regeneration, and inhibition of free radical production.

What does leucine do?

Leucine is the Swiss army knife of amino acids. It can do almost anything.  Leucine is likely best known for its role in protein synthesis. Its ability to enhance muscle protein synthesis is due not only to its ability to grow muscle, but also to prevent the breakdown (catabolism) of muscle. Reducing catabolism and increasing protein synthesis results in an even greater muscle protein synthesis. This muscle growth is not only important for athletes and active individuals. As we age, we gradually lose muscle mass. When this loss in muscle rises to the level of clinical significance it is called sarcopenia.  This loss of muscle mass significantly increases the risk of fracture (58%) and can play a large role in dictating our independence while we age.  Sarcopenia impacts between 25 to 45% of older adults in the United States. 

In addition to its muscle growing (and keeping) capabilities, leucine is also vital for the regulation of blood sugar levels (aka glucose homeostasis), growth and repair of muscle and bone tissue, growth hormone production, and wound healing.

How does leucine work?

Within the body, there is a giant infrastructure of highways and backroads that are constantly working to shuttle hormones and substances that control many of our bodily functions.  One such highway is termed the mTOR (mammalian target of rapamycin) pathway.  This pathway is the main way in which we transport the substances necessary to regulate muscle growth and metabolism. Leucine activates the mTORC1 pathway.

Leucine is a versatile amino acid.  It also has the ability to regulate metabolism through alternative signaling pathways, such as AMP-activated protein kinase (AMPK) or general control non-depressible kinase 2 (GCN2). The activation of the later pathway may be responsible for leucine’s ability to enhance insulin sensitivity.   

The branched chain amino acids, which include leucine, are unique in that they are not highly metabolized by the liver.  They bypass the portal venous system following their intestinal absorption. This means that they are not highly metabolized by the gut or liver before reaching systemic circulation like other amino acids. 

Leucine may also have the capacity to influence our food intake by affecting the central nervous system.  However, research results are inconsistent with some studies showing a reduced caloric consumption with leucine supplementation and other studies revealing no change in food intake.  Further studies will be needed in order to determine the reasoning behind the mixed results.  As new research emerges, we will be sure to keep you updated in future blogs.

How does leucine impact glucose regulation?

When it comes to our metabolism, leucine packs a powerful punch.  It regulates glucose with two different approaches: (1) by reducing the glucose spike and, (2) by enhancing insulin release. Studies have shown that when leucine was consumed with glucose, just as GOOD IDEA is consumed with your meals, the 2.5-hour glucose area response is reduced by 50%. Leucine also increases the insulin response by 66%. This means that the body reduces the glucose spike that can harm your metabolic health, induce cravings, and cause low energy levels.  It also increases the amount of insulin, a hormone that helps to take the glucose out of the blood and put it to use as energy within the cells. 

In the short term, this can improve energy levels and reduce cravings.  Over time, enhanced blood sugar regulation can improve our metabolic health while reducing the risk of diabetes and cardiovascular disease.

Is leucine safe?

Not only is leucine safe, but it is also essential. Leucine is necessary for our body to build proteins, power our immune systems, regulate our blood sugar, fuel muscle growth, and assist with neurotransmitter production.  Our bodies also have a built-in safeguard against harmful levels of leucine.  All of the branched chain amino acids have self-regulated oxidation. High BCAA concentrations prompt higher levels of other complexes (BCAT and BCKDK) that prevent leucine content from reaching toxic levels. This allows the body to safely and effectively utilize leucine.

Is leucine an ingredient in GOOD IDEA?

Leucine, isoleucine, valine, threonine, and lysine monohydrate are the five amino acids in each GOOD IDEA beverage.   In addition to tasting great, each GOOD IDEA drink supplies the body with leucine, helping to provide energy throughout the day, build muscle, reduce cravings, stabilize blood sugar, and boost the immune system.  Check out the GOOD IDEA blog in order to learn more about how each of the ingredients in GOOD IDEA impacts our metabolic health and blood sugar.

Author: Dr. Colleen Gulick