Benefits of the amino acid L-Leucine

Benefits of the amino acid L-Leucine

L-leucine is one of the branched chain amino acids (BCAA’s). It is an essential amino acid that cannot synthesized by our body. This means that it has to be obtained from food or dietary supplements.

What is Leucine?

L-leucine effectively regulates the blood sugar levels and it also increases the production of the growth hormone. It can be combined with isoleucine and valine to protect and provide fuel to the muscles. Moreover, it helps to increase our resistance and energy.

The main sources of leucine are found in those of animal origin. This is due to the fact that they are complete protein sources which provide all the amino acids, both essential and non-essential.

It is involved in the creation of new tissues, apart from several physiological processes connected to different areas: wound healing, tissue repair and even energy production.

Properties of Leucine

It is the most abundant BCAA in the muscle tissue. In this sense, we could say that the skeletal muscle is made up of almost a third of BCAA’s.

One of their main features is being used as fuel under certain circumstances, such as a demanding physical effort.

After said activity, the BCAA’s will drop both in the blood plasma and in the muscle mass.

What is Leucine used for?

It preserves the muscle mass

Like other essential amino acids, L-leucine helps to preserve the muscle mass. This amino acid helps to protect the muscle tissue, which is why it is not broken down so quickly as we grow old. It can also shorten the recovery period from muscle and skin injuries.

This is the reason why many bodybuilders and athletes use leucine supplementation

L-leucine is important to regulate the protein synthesis and it is essential to create muscle tissue after an intense workout. It is mainly concentrated in the muscle tissue. That is the reason why it helps to reduce the breakdown of these tissues during endurance workouts.

Those who are dedicated to bodybuilding tend to use supplements to make sure that they have enough L-leucine. This is done to prevent the catabolism of the tissues and to create muscle mass.

Leucine and Working Out

It is important to maintain the stimulus to avoid losing muscle mass

It stimulates weight loss

Leucine can encourage weight loss by increasing the metabolic rate during physical exercise. It can help to burn visceral fat, which is the deepest fat layer of the body. Usually, it is not affected neither by the diet nor physical exercise.

Anti-catabolic properties

When it comes to following a hypocaloric diet to lose fat, one of the main problems is losing muscle mass due to the energy deficit. This could potentially lead to loss of our valuable muscle tissue if we continue to perform physical activities.

In these circumstances, the leucine supply could drastically reduce the muscle catabolism, helping to preserve our muscle mass.

It regulates the sugar levels

Leucine is not the only amino acid that can produce glucose. However, it stands out for its ability to regulate the sugar levels healthily. This amino acid can also replace glucose while fasting, which is an exclusive property of this amino acid.

In an article published in “The Journal of Nutrition”, the food scientist Donald K. Layman informed that leucine is promising in aspects related to regulating the metabolism. This scientist also explained that leucine improves the glucose and insulin homeostasis by stabilizing the blood glucose levels.

mTOR Pathway

Leucine is one of the key elements that activates the necessary physiological process in order to create new proteins. This process is called the mTOR (mammalian target of rapamycin) pathway. To put it briefly, it is a molecule that works like a switch, triggering the mechanism for the synthesis of new proteins.

Sarcopenia Leucine


It involves losing the ability to create new muscle structures and muscle power as we grow old. This issue can significantly condition and affect our health and quality of life.

Consequently, the symptoms only get worse if we suffer an accident, like falling. This is the reason why taking Leucine can improve the preservation of our muscle tissue.

Leucine Supplement

An “easy” way of adding l-leucine to our diet is through leucine supplements, since there is a wide range of combinations and formats. Most of the time, it tends to be combined with other two branched amino acids (valine and isoleucine).

Leucine tends to have a higher percentage than valine and isoleucine in these combinations. In fact, the most frequent ratio is 2:1:1. However, you can find products that have a 12:1:1 Leucine ratio when compared to the other amino acids. This is the case of Evobcaa’s by our brand RawSeries, and we have also added L-Glutamine to its formula.

In this article, we will focus on supplements which have leucine as the only ingredient

How to choose the best Leucine

You should make sure that your leucine supplement has the following features:

  • Vegetable Origin.
  • Obtained through a fermentation process.
  • GMO-free, which means that it does not have genetically modified organisms.
  • Instant, which means that its dissolution should be practically instantaneous. If it does not meet this requisite, we will have a hard time dissolving it completely.

Reliable leucine

A reliable brand will always share this information without any issue. This is the only way to ensure that we are purchasing and taking the best Leucine. We would also like to clarify that everything has its fair price and nobody will give you anything for free…

We have seen different companies (we would rather not say any names, all of them are from the competence) that sold leucine without stating its origin. Most of the time, they come from unreliable sources which are not GMO-free nor from vegetable origin… Actually, most of them come from hairs and they are not instant either…

Fermentation and dissolution

In terms of the manufacturing process, it should have been obtained through fermentation. This is a process that improves the preservation of the final product. Moreover, it eliminates harmful bacteria and provides a better absorption and digestion.

Finally, another aspect that should be kept in mind is its dissolution. BCAA’s or branched chain amino acids are hydrophobic: to avoid any issue, we should consider buying a type called “Instant Leucine”, which provides an excellent solubility.

  • Highly efficient anabolic formula
  • Designed for an immediate supply of amino acids for the skeletal muscle
  • Improved protein synthesis
  • Reduced protein breakdown

Leucine peptides, what is the best leucine?

Leucine peptides are a powerful anabolic formula made of PepForm® Peptides, which have a higher bioavailability. Thanks to this, it will discharge the amino acids into the muscle tissue in the fastest and most efficient way.

PepForm® Peptides is a patent from the company Glanbia Nutritionals. They have developed a product that improves the amino acid supply to the muscle tissue to contribute to the protein synthesis and muscle growth.

With its formula, PepForm® Leucine provides a more soluble form with a higher bioavailability than the rest of L-Leucine products. This is due to the fact that it manages to supply a higher percentage of leucine peptides from whey protein.

What are peptides?

Peptides are molecules made up by at least 2 amino acids. Proteins are made up of peptide chains and our body needs to digest them in order to absorb them. Thus, they are broken down in the digestive system and absorbed in the intestine. By using peptides, we will “avoid” this step, since we could say that they go straight to the intestine.

Leucine peptides

Absorption of the Leucine Peptides

Once we take them orally, they will be absorbed faster than complete proteins or other type of free form amino acids. Consequently, we will be able to trigger a leucine peak in the blood plasma in a few minutes.

The body has the ability to absorb the peptides faster, which will be a task performed by the intestine. More specifically, it will be done by the peptides transport system Pep1, which occurs in the enterocyte apical membrane in the small intestine.

Benefits of Leucine Peptides

L-leucine belongs to the branched chain amino acids (BCAA’s), which are classified as essential amino acids. The amino acid Leucine is the one responsible for the activation of the mTOR pathway. This is a metabolic signalling process that activates the protein synthesis mechanisms.

The main reason is the speed and absorption when compared to other formulas. This leads to a highly effective anabolic hormone environment.

Leucine Peptides and Endurance Activities

They can support sportspeople and athletes who do sports that involve resistance for long periods of time. Thus, they will be able to improve the glycogen recharge and its absorption on behalf of the muscles. This is due to the fact that peptides can increase the glycogen synthesis once the effort is over.

If we used them as a pre-workout, we will be able to save more glycogen. This will increase the endurance or resistance component, since it will enhance the use of fatty acids.

Who can benefit from Leucine Peptides?

  • They are aimed at those who have great expectations in terms of muscle growth. However, they should follow a workout and nutritional plan according to such objective.
  • Sportspeople and athletes that perform activities with a high physical wear due to a high energy and physical demand. Moreover, it can provide an extra supply that will help them recover and regenerate the tissues.
  • There is also another group that can benefit from a leucine peptides supply. The elderly who also do sport, since their ability to synthesize proteins has deteriorated with the passing of time. In addition, it can benefit those who suffer sarcopenia and who want to preserve their muscle mass.

Leucine for high intensity sports

What types of Leucine can we buy?

Leucine is mainly available in two formats:

Leucine Powder

This is the best choice from our point of view. It is quite comfortable if you want to combine it with pre, intra, or post-workout shakes. Moreover, it is also the most affordable format.

Leucine Tablets or Capsules

On the contrary, it is advisable to purchase capsules or tablets if you are not going to combine it with other supplements. Also, do not choose this format if you are sensitive to strong flavors. It has a bitter flavor that is not really pleasant if you just take it alone with some liquid…

The main inconvenient of this format is that we will have to take many capsules in order to meet the requirements of this amino acid. Moreover, it is also more expensive than the powder format.

What is better, taking amino acid powder or capsules/tablets?

When should we take Leucine?

It is up to you to take this amino acid alone or combined with the other BCAA’s. Regardless of your choice, it is advisable to take it:

  • On an empty stomach before doing physical exercise
  • Combined with a protein source after the workout, such as a protein shake
  • With those meals that have a low protein content
  • Highly efficient anabolic formula
  • Designed for an immediate amino acid supply for the skeletal muscle
  • Improved protein synthesis
  • Reduced protein breakdown

When to take a protein shake

Dose of Leucine

According to the experts, the recommended dose of leucine moves between 2,000 and 5,000mg per serving.

Where can we buy Leucine?

You can purchase leucine in many online and physical stores, sport supplementation stores, herbalist’ shops, parapharmacies, etc… We suggest buying Leucine by RawSeries, which meets all the requirements in terms of quality with a very competitive price.

Foods rich in Leucine


Soy is one of the most available and nutritious legumes in the world. It is not only rich in proteins, omega-3 fatty acids, and vitamin K, but it is also one of the best natural sources of leucine. 100g of soy provide 2.97g of leucine.


Eggs are an excellent dietary source of leucine. A whole fresh egg has approximately 1.09g of leucine. But if you are worried about their cholesterol content, but you still want the leucine, you just have to eat the egg whites.

Peanuts source of leucine


Raw peanuts are a rich source of leucine, with 1.67g of leucine every 100g. The experts have stated that they are a very healthy product since they lower the risk of suffering a coronary disease. Even though peanuts and peanut butter have a bad reputation for not being very healthy due to their high percentage of fats. Only one or two spoonfuls should be enough to obtain all the benefits that we need.


Milk is another source with a lot of natural leucine. 100g of milk has 1.6g of leucine. Drinking low fat or skimmed milk is a good way of increasing the leucine supply of the diet without adding extra fats and calories present in whole milk.

Milk leucine source

Red Meat

The leucine content in a 100g beef steak will approximately provide 1.75g of leucine. Red meat has more saturated fats than other meats, which is why you should consume it moderately.


Its seeds, butter or paste has 1.36g of leucine per 100g. The seeds are usually added to different bakery products, salads and soups.


You can use chickpeas to cook soups, salads or you can also eat them alone. They have 1.37g of leucine every 100g.

Foods rich in leucine


  1. João A.B. Pedroso, Thais T. Zampieri, and Jose Donato, Jr. (2015). Reviewing the Effects of l-Leucine Supplementation in the Regulation of Food Intake, Energy Balance, and Glucose Homeostasis.
  2. Horstman AMH, Kouw IWK, van Dijk JW, Hamer HM, Groen BBL, van Kranenburg J, Gorissen SHM, van Loon LJC. The muscle protein synthetic response to whey protein ingestion is greater in middle-aged women when compared with men. J Clin Endocrinol Metab. 2018 Nov 12. doi: 10.1210/jc.2018-01734.
  3. Yoshii N, Sato K, Ogasawara R, Nishimura Y, Shinohara Y, Fujita S. Effect of Mixed Meal and Leucine Intake on Plasma Amino Acid Concentrations in Young Men. Nutrients. 2018 Oct 18;10(10). pii: E1543. doi: 10.3390/nu10101543.

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Melanie Ramos
Melanie Ramos uses the HSN Blog to share the latest information and content, so that all those readers who want to learn.
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