Leucine, the first of the Branched Chain Amino Acids

From a basic point of view, amino acids are organic acids (COOH) linked to an amine function (NH2). Between the organic acid and the amine, a radical is added which gives the identity of this amino acid. If you know the BCAA – Branched Chain Amino Acids – you also know Leucine. As you know, there are three BCAAs: Leucine, Isoleucine, and Valine. Called branched or branched because of their particular molecular structure, BCAAs are among the essential amino acids. Your body therefore cannot synthesize them from other molecules or other amino acids , essential or not. Today, a majority of popular articles deal with Leucine and its role in muscle growth. So what is the reality?

Leucine and its essential role in muscle growth

Leucine is still considered the main amino acid for muscle growth and protein synthesis at the cellular level. Let's say it will trigger anabolism. Most scientific studies have highlighted the role of leucine on hypertrophy and protein synthesis. proteins as long as a sufficient amount of protein and amino acids is taken with it. Indeed, it is true that it triggers protein synthesis at the cellular level but it does not do it alone. To this end, we often talk to you about the aminogram. It is simply the relative balance of each amino acid in a protein. When one or more amino acids are missing, the aminogram is insufficient in quality and protein synthesis will be too. BCAAs , while they play a role in anabolism and energy, can only do so much on their own. However, the amount of Leucine will ALSO determine whether a protein will be used for muscle protein synthesis or for energy.

A little more leucine triggers protein synthesis but too much leucine stimulates gluconeogenesis

Leucine has the property of being insulinogenic, meaning that it plays a role substantially similar to insulin. This also explains why an excessive intake of Leucine only precipitates glucoforming amino acids towards gluconeogenesis. Conversely, a few additional grams of Leucine promote protein anabolism, whether it is a whey protein , casein or a vegetable protein (peas for example), as scientific studies have demonstrated.

To this end, Leucine will trigger protein synthesis through the pathway mTOR/AKT/p70S6k. We've often talked about the mTOR pathway to discuss the anabolic role of this amino acid. However, leucine alone won't work miracles if other proteinogenic amino acids aren't present in your diet. This is the case, for example, with isoleucine, an amino acid similar to leucine. Scientific research has proven that the latter stimulates the uptake of glucose by cells by activating the binding of GLUT4 to cell membranes, allowing increased storage of glycogen by the muscle. The third branched-chain amino acid, L-valine, is also involved in energy management by our muscle cells.

Both Leucine, Valine and Isoleucine must be supplied to your muscles in sufficient quantities.

These simple considerations should make you think that all three BCAAs have their uses. BCAA formulas like 4:1:1 or worse, 8:1:1 are nothing more than boxes of Leucine, or Valine and Isoleucine are present in much too small quantities. Without being able to formally demonstrate it, it is likely that these BCAAs too low in Valine and Isoleucine are rather counterproductive than effective in stimulating muscle growth.

On the other hand, why should you pay for a box of BCAA at the price of Leucine which should, in this case, cost you much less? From there, nothing prevents you from buying a Leucine powder supplement and adding 3 to 5 grams to your protein, depending on the amount of protein powder you take. For 30g, add 3 grams of Leucine, for 40/45g, add about 4g of Leucine.

Scientifically, we know that Leucine stimulates anabolism and the maintenance of muscle mass, but we also know that it will have more influence on protein synthesis at 40 or 50 years of age than it does at 20 years of age. The same goes for nutritional protein intake, which must increase with age to promote the maintenance of muscle mass. In terms of the aging of the body, this results in an increase in splanchnic extraction. That is to say, the older you get, the more amino acids your intestines will retain for their own needs. As a result, the amount of amino acids in the blood will decrease with age. Anabolism and the maintenance of muscle proteins would therefore be reduced, which is not desirable.

Combined with Glycine, this BCAA can help you maintain muscle anabolism

Gerontology specialists tend to assert that protein intake, but also leucine intake, can counteract this age-related deficiency. This is also true for glycine. Clinical experiments have also proven that from the moment when an intake is no longer sufficient to maintain muscle anabolism, a glycine supplement can contribute to maintaining anabolism. In other words, Glycine and Leucine are two isolated amino acids that we can recommend supplementing with, especially as you age. Also, remember that longevity is linked to lean muscle mass, as scientific research has shown. From this, it's also important to note that the notion of essential or non-essential amino acids is a relative value. Your metabolism is incredibly complex, which means it can't be reduced to basic principles.

Glycine and Leucine have a little-known nutritional benefit for athletes

Although it is difficult to recommend taking an isolated amino acid, Leucine and Glycine are exceptions, as long as they are not taken in excess. In fact, a few grams of Leucine and Glycine can help stimulate and maintain anabolism, as long as the other amino acids are also present in sufficient quantities . Thus, the intake of amino acids, like any other nutrient, is a question of balance. Taking 10 grams of this BCAA at once will only precipitate the conversion of amino acids into glucose but will not do anything really significant for the synthesis of Protein . The rule of balance, or homeostasis in biochemistry, is a rule that should never be forgotten. A few grams added to a drink, once or twice a day, could have a positive effect on anabolism, even if you are not yet over 60 years old. In fact, it is certainly a very useful supplement after 40, if you do bodybuilding, and even for sedentary people. Remember, however, that BCAAs must be combined with other essential amino acids to best stimulate muscle development.