Leucine Threshold: What It Is And How To Get There

The human body is an amazing machine that requires careful maintenance to run efficiently and properly. There are numerous vitamins, minerals, nutrients, and amino acids that need to be consumed to keep the body moving. Consuming a healthy diet filled with plant proteins, water and foods rich in antioxidants and nutrients makes running your body easy. Branch Chain Amino Acids play a huge part in allowing our muscles to work and grow. One BCAA, leucine, has been found to improve muscle growth better than all the rest, but there’s a threshold you need to reach before this amino acid can work its wonders.  

What is Leucine?

Leucine is a branch chain amino acid found in protein.  It is considered an essential amino acid and therefore it must be supplemented in your diet for you to receive it and benefit from it, it is not synthesized in the body. Leucine is found in protein sources such as egg whites, animal protein, and plant protein sources like soy and LENTEIN. This essential amino acid is most well known in bodybuilding circles as the amino acid you need to stimulate muscle growth. This is because it provides muscles with the nutrients and activates the growth pathways needed to synthesize. Specifically, its ability to stimulate skeletal muscle synthesis is ten times better than any of the other BCAAs.

While not everyone is looking to build a body akin to Dwayne “The Rock” Johnson, health and growth of skeletal muscles is important to everyone. Adding leucine to any diet will help enable muscles to grow and thrive. In fact studies have shown that the addition of leucine in the diets of people who in general eat low-protein meals, specifically the elderly, have helped increase skeletal muscle gains. The amount of leucine one consumes is important to whole body wellness.

How does leucine stimulate muscle growth?

Leucine stimulates muscle growth by activating a muscle building pathway called mTOR (mechanistic target of rapamycin). Elevated leucine levels alert mTOR that there is sufficient nutrients and amino acids to expend energy on muscle building. When there is not enough leucine in the body, mTOR is disabled, which makes it extremely important that you reach the leucine threshold if you want to help your muscles grow.

The Leucine Threshold

In order for your body to utilize the muscle-building power of leucine, you must consume enough of it. Our bodies absorb 100 percent of the amino acids we consume. However, a very small percentage of that actually goes to muscle building. Other organs and muscles in our bodies also require amino acids. When you eat protein, amino acids are distributed through the digestive tract to your liver, kidneys, cardiac and smooth muscles, and even to tissues like the skin. To reach a leucine threshold, where the amount of amino acids you consume are used to synthesise skeletal muscles instead of being delegated to the rest of the body, you need to make sure you are consuming enough protein with a high leucine content at one time. One study found that it was necessary for older populations to consume higher concentrations of leucine in order to reap the benefits. While in younger populations the mTOR pathway is more sensitive and lesser amounts can provide consumers with skeletal muscle synthesis. Further, it appears that once you have reached the leucine threshold there is a “refractory period” where the body must use the amino acids it has before it can begin to utilize more that enter the body. To achieve this threshold and ensure you are getting the most out of your nutrients, it seems to be best to eat a large amount of protein in one meal, and then “replenish” your body with protein after four to five hours instead of constantly eating small amounts of protein throughout the day.

The amount of leucine contained in a protein needed to achieve this threshold, according to current research, is between 26 and 41 percent leucine, or 3.2- 4.4g. For reference a 4.7oz steak will provide you with this amount of leucine, as will 5 large eggs.

Getting the right amount of nutrients and amino acids can be difficult to understand.  However, choosing a healthy diet with ample fruits, vegetables, and sustainable proteins like LENTEIN can help you reach your leucine threshold and maintain a healthy body.