Last updated: August 12, 2021

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Today we are going to talk about an essential amino acid for the maintenance of the body's muscles: leucine. Found both in food and in food supplements, leucine is the darling of exercisers.

In this article, we will explain the main functions of leucine, how you should consume it and what you should take into account to buy the best supplement available on the market.


  • Leucine is one of the amino acids that our body needs to synthesise proteins.
  • This is why it must be ingested either through food or supplements.
  • It is possible to consume leucine alone or as an integral part of BCCA.

The best Leucine: Our Picks

Buying guide

To start taking leucine supplementation it is important that you consider a few factors, taking into account your eating habits, your health condition and replacement needs.

In this Buying Guide you will find all the necessary information to clear all your doubts about this food supplement.

Homem pegando haltere.

The leucine is an amino acid that helps in the maintenance of the muscle. (Source: Victor Freitas/

What is leucine and what is its function?

Leucine is one of 20 amino acids that the body's cells use to synthesise proteins. As it is not produced by the body, leucine needs to be consumed through food or supplementation.

Also known as L-leucine, leucine makes up the set called "branched chain amino acids", popularly known as BCAAs. And its main function is muscle maintenance.

Therefore, leucine supplementation ends up being common when there is a loss of protein in intense bodybuilding workouts, for example, or in the case of some diseases, such as malnutrition.

Mulher preparando bebida com suplemento.

The leucine has several benefits for the organism. (Source: belchonock/

Besides acting in the maintenance of the muscular mass, leucine also helps in the muscular recovery, in the reduction of the sugar levels in the blood, in the increase of the defences of the organism and in the healing of fractured bones.

It is worth mentioning, however, that for leucine to be effective in the body, it is necessary that you have a routine that includes a healthy diet and constant physical activity.

Isolated leucine or BCAA: which is the best supplement?

As we have seen, leucine is an integral part of BCAA (Branched-Chain Amino Acids). In addition to leucine, the BCAA is made up of two other essential amino acids which are not produced by the body: L-Valine and L-Isoleucine.

These amino acids, despite not being produced by the body, are essential because they help the body's cells to produce proteins.

But then you may ask yourself, why consume leucine isolate when I can supplement with BCCA?
This is actually a choice that you should make in conjunction with your doctor or nutritionist, according to your eating routine and nutritional needs.

Vários potes de suplementos.

BCCA is formed by leucine, valine and isoleucine. (Source: Bavl/

But in general, it is possible to say that if you already make use of a diet or protein supplementation with, for example, Whey Protein, it is likely that the use of isolated leucine is more beneficial.

This is because, while leucine acts directly in the muscles, valine and isoleucine transport it to the cells. This is also why the amount of leucine in supplements is always higher than the other two amino acids.

However, if your diet is not high in protein, most experts believe that ingesting isolated leucine will not offer the best results. This is because leucine needs the other amino acids to be transported efficiently. In cases like this, the most recommended is to use a BCAA supplement.

What are the sources of leucine?

Leucine is usually found in high protein value foods, both of vegetable and animal origin, such as meat, fish, eggs, milk, beans, potatoes, oilseeds, among others.

By eating a balanced diet rich in leucine you help to reduce the loss of muscle mass. And this is especially true for older people.

Did you know that after the age of 40, we start losing 0.5 to 2% of muscle mass per year?

Because of this, the elderly suffer more from conditions such as atrophy, loss of muscle fibres and increased accumulation of fat between the fibres. Eating foods rich in leucine or supplementation is one way to prevent and treat these problems

In addition to being present in food, leucine is also found in high protein food supplements such as Whey Protein and BCAA.

For you to know how to use food in your favour and consume leucine correctly, check out the table below which shows the foods rich in this amino acid.

Foods rich in leucine Energy in 100g
Peanut 577
Cashew nut 609
Brazil nut 699
Cucumber 15
Tomato 20
Eggplant 19
Cabbage 25
Okra 39
Spinach 22
Beans 360
Peas 100

Can leucine help with muscle mass gain?

As we have seen, leucine is an amino acid that acts in the maintenance and restoration of muscles. And, therefore, it can indeed help in the gain of muscle mass.

The fact is that it is able to activate mTOR, a protein that is associated with the growth and development of cells, participating in anabolic and catabolic processes in general. In other words, it helps to increase muscle mass.

For this reason, experts say that leucine supplementation taken after an exercise session will stimulate cellular hypertrophy.

Mulher puxando peso.

Leucine helps in gaining muscle mass. (Source: The Lazy Artist Gallery/

No wonder leucine is a favorite of bodybuilders and professional athletes because of its ability to accelerate muscle hypertrophy and improve performance during workouts.

But besides being beneficial for those who exercise and want to gain muscle mass, leucine is also widely used by seniors to improve physical mobility and reduce muscle atrophy.

When is leucine supplementation necessary?

As we have seen, it is possible to maintain adequate levels of leucine through a balanced diet. However, there are some situations which may require dietary supplementation of this amino acid.

In all cases, however, the most important thing is to identify the need for leucine supplementation by carrying out tests and being monitored by a doctor or nutritionist.

With this in mind, here are some cases in which a leucine supplementation may be indicated:

  • Deficient diet: A diet poor in vitamins and nutrients can cause nutritional deficiencies, including that of leucine. The ideal, therefore, is that you acquire healthy eating habits by consuming varied foods rich in this amino acid.
  • Malnutrition: Diseases, metabolic imbalances and poor diet can cause malnutrition. In this case, supplementation may be necessary.
  • Intense physical activities: Weight-lifting, for example, uses up a lot of energy and generates intense muscular effort. In these cases, leucine supplementation may be indicated to optimize the practice and increase muscle mass.
  • Muscleweakening: The loss of muscle mass can occur for various reasons: Malnutrition, malnutrition, sedentary lifestyle, diseases, age problems, among others. Leucine supplementation is usually indicated also in these cases.

Leucine: how to take it?

Before starting the use of any food supplement it is necessary that you consult with a health professional.

Only a doctor or nutritionist will be able to assess the need for supplementation.

Only a doctor or nutritionist will be able to assess the need for leucine supplementation and, most importantly, the best way to consume this amino acid.

However, in general, experts say that the recommended daily dose of leucine should not exceed 5 grams.

What are the side effects of leucine?

So far there is no proven contraindication to the use of leucine as a dietary supplement.

However, just like any other supplement, leucine is not free from the possibility of causing discomfort and side effects.

It is already known that the consumption of leucine in very high doses can cause anxiety, gastric discomfort and fluid retention.

How much does it cost and where to buy it?

The manufacturer brand, the composition and formula, as well as the quantity sold, are items that can influence the price of the leucine supplement. Thus, the price of leucine can vary between £35 and £200.

It is easy to find leucine on sale.

On the other hand, it is easy to find leucine on sale. Either in specialized supplement shops or department stores and even in big supermarket chains, such as Lojas Americanas and Extra.

Still, if you want to buy leucine from the comfort of home, have more options of brands to choose from and still benefit from promotional prices, we recommend you buy leucine online, in shops like Amazon Brazil, for example.

Purchase criteria: what to consider when choosing leucine

Once you have identified the need for leucine supplementation, it is now time to choose the best product among so many on sale. To help you in this process, we have listed the main criteria you should consider before buying leucine. They are:

Below we will explain each of these factors in detail.


The first criterion you should analyze is the formula of the supplement. This is because as we have seen, you can choose either leucine alone or BCCA, which is the supplement composed of leucine, isoleucine and valine.

But in addition, it is also important that you check other elements that may exist in the supplement formula.


Not infrequently, you will find leucine along with doses of vitamin B6 and Chromium, for example. Once again it is worth emphasizing the importance of monitoring a specialist to analyze the need for supplementation of these vitamins and minerals.


You can consume the isolated leucine or the BCCA.
(Source: Bru-nO/

Capsule or powder

Next, we recommend that you take into account how you will consume the leucine supplement. In this regard, you can opt for its powder or capsule form.

It's worth noting that taking leucine in capsules, although the most convenient form, can often be more uncomfortable, especially if you have difficulty swallowing.

The powdered version can be more versatile as it can be mixed into vitamins and shakes.


Also evaluate the dosage of leucine recommended by the manufacturer brand. In the case of tablets, for example, you may need to take three or more capsules a day.

If you choose leucine powder, the supplements usually come with meters for you to do the dosage. Also, take into account the amount of leucine in each dose, which can vary from 980mg to 5g.


Finally, note the amount of leucine that comes in the package. To choose the best quantity and ensure the best cost-benefit, take into account the recommendation for use of your doctor. After all, the larger the package, in general, the greater the cost-benefit.

(Source of the highlighted image: Eugeniusz DudziÅ"ski/