The Branched Amino Acids


The branched chain amino acids (English acronym BCAA) are a group of three essential amino acids, respectively called L-Leucine, L-Isoleucine and L-Valine.

In recent years, branched-chain amino acids have conquered the world of nutritional supplementation, particularly that of sports dietetics.

The high muscular tropism, the absence of noteworthy side effects and the potential ergogenic and myoprotective role, have facilitated the use of BCAAs among athletes of different disciplines.

This diffusion has not been undermined by the wide availability of these nutrients in various foods, nor by the presence of conflicting and contradictory studies concerning the real usefulness of BCAA supplements in improving athletic performance.

Branched Amino Acids in Foods

The branched amino acids are present in various foods, especially of animal origin, such as chicken, beef, milk and fish, but also in legumes.

As shown in the table, only 100 g of bresaola or parmesan are able to provide more than 5 g of BCAA.

Branched amino acids in food Vs branched amino acids in supplements
CHICKEN 150 gTUNA WITH OIL 112 gBRESAOLA 100 g5 cpr of a "famous" supplement


Why are BCAAs used? What are they for?

In the clinical setting, BCAAs are used in particular pathological conditions, such as liver disease, hepatic encephalopathy and chronic obstructive pulmonary disease.

Given the high protein turn-over of tissues in active regeneration, the BCAAs are also used in the recovery phases from large traumas and burns, and in some states characterized by a progressive decrease in lean mass (cachexia and sarcopenia).

Despite the clinical importance of these nutrients, the most significant use of BCAA supplements certainly affects the sporting environment.

In this context, branched amino acids are used:

  • As an ergogenic aid before performance;
  • As an anticatabolic remedy;
  • As a useful supplement to reduce muscle damage caused by intense physical exercise;
  • As a useful supplement to reduce the feeling of central fatigue and muscle fatigue;
  • As a useful supplement to accelerate recovery times and optimize muscle growth.

The wide use of BCAAs in sports would derive mainly from their metabolic role and high muscular tropism.

These amino acids, in fact, preferably reach muscle tissue, regulating both oxidative and biosynthetic functions, and consequently modulating both the catabolic and anabolic phases.

Property and Effectiveness

What benefits have the BCAAs shown during the studies?

Leaving aside the clinical applications of BCAAs, which go beyond the use of these nutrients as supplements, the literature shows interesting, albeit conflicting, data relating to the importance of BCAAs in sports.

BCAA and central fatigue

Tryptophan (TRP) is an essential amino acid and is the precursor of serotonin, a brain neurotransmitter.

Tryptophan circulates in the blood linked to the most important plasma protein, albumin.

We have seen that the more the concentration of BCAAs in the blood decreases, the more tryptophan can reach the brain and the greater the sensation of fatigue.

During prolonged physical exercise there is an increase in plasma levels of fatty acids, consequent to their mobilization to satisfy energy demands. Fatty acids also circulate bound to albumin, for which they have a very high binding affinity; their increase in circulation displaces tryptophan from albumin, with a consequent increase in free tryptophan.

Increased free TRP makes it easier for the brain to pass and increases the production of serotonin in the brain.

An increase in serotonin, in turn, increases the degree of fatigue and fogging at the central level, resulting in the onset of fatigue.

Therefore an adequate integration of branched chain amino acids could prevent the appearance of the fatigue symptom during strenuous exercise, competing precisely with the Tryptophan for the "central" transporter of these amino acids.

BCAA and ergogenic activity

Until a few years ago it was believed that proteins were not used for energy purposes during exercise, provided that the caloric supply in carbohydrates and fats was adequate.

Today, several studies have shown that the oxidation of amino acids for energetic purposes occurs already in the first phases of the exercise and acquires more and more importance with the persistence and the intensification of the same.

The use of BCAAs for energy purposes is in any case linked to the body's energy stocks (lipids and glucides): the more these are reduced and the greater the oxidation of the carbon skeleton of the branched chain amino acids.

Endurance muscle activity, if particularly prolonged, is characterized by the reduction of protein synthesis due to the lack of amino acids that occurs following their use as an energy source. This degradation is also prolonged in the first recovery phase to supply and damaged muscle fibers.

BCAA and myoprotective activity

According to some authors, the use of BCAAs, in the phases that precede training, would have been important in preventing muscle damage induced by intense physical exercise.

It is known, in fact, that intense physical activity - characterized by an increased oxidation of BCAAs - can induce a proteolytic action against myofibrils.

This activity can be monitored through the concentrations of some markers, such as lactate dehydrogenase or creatine kinase.

The preventive use of BCAAs would be effective in reducing the blood concentrations of the aforementioned markers, thus demonstrating myoprotective action.

BCAA and muscle recovery

The effectiveness of BCAAs in the post-exercise phases would be mostly due to the presence of Leucine.

Several authors have indeed demonstrated how Leucine, and its direct catabolites such as HMB, are involved in different metabolic pathways, enhancing the activity of transcription factors involved in protein synthesis. This activity would be proportional to the intensity of the muscular effort faced.

Doses and method of use

How to use the BCAAs?

The use of BCAA supplements is widespread especially in sports.

Leaving aside some special medical indications, for which the use of BCAAs should be strictly supervised by your doctor, the generally most used dosage is that of 1g of BCAAs per 10 kg of body weight (despite ministerial guidelines refer to maximum daily dose i 5g).

Classically, the intake of branched amino acids in sports can be divided into:

  • Pre-training ration, necessary to reduce the catabolism associated with intense training and to simultaneously reduce the feeling of fatigue. In the pre-training phase the BCAAs would have proved particularly effective also from an ergogenic and myoprotective point of view.
  • Post-training ration, effective in supporting the functional and structural recovery of the muscle, optimizing the recovery phase.

Over the years, formulators have developed various BCAA supplements, which differ above all in:

  • the association with other elements - such as group B vitamins -
  • the breakdowns of individual amino acids.

With regard to this last point, today it is possible to find on the market:

  • BCAA 2: 1: 1, that is BCAA with double Leucine ratios compared to Isoleucine and Valine;
  • BCAA 4: 1: 1, with quadruple ratios for Leucine;
  • BCAA 8: 1: 1, with quantities of Leucine 8 times higher than those of Isoleucine and Valine.

Directives of the Ministry of Health for BCAA Integrators

  • Maximum daily intake: 5 g as a sum of leucine, isoleucine and valine.
  • Indications: integration of the sportsman's diet
  • Warnings to be reported on the label: Do not use during pregnancy and in children, or in any case for prolonged periods without consulting a doctor

The highest Leucine concentrations would be indicated in high intensity disciplines and in improving post-workout muscle recovery.

Despite the extensive use made of BCAA supplements, a healthy and balanced diet could easily satisfy even the most demanding needs, making additional supplementation practically useless.

Side effects

The use of BCAAs has generally proved to be safe and well tolerated.

A recent study, however, would indicate an increase in mortality in patients with amyotrophic lateral sclerosis undergoing therapy with high doses of BCAAs.


When should BCAAs not be used?

The use of BCAAs is contraindicated in case of hypersensitivity to any component of the supplement in question, and in the rare cases of congenital enzyme deficiencies.

Pharmacological Interactions

Which drugs or foods can change the effect of BCAAs?

At the moment, noteworthy drug interactions are unknown.

Precautions for use

What do you need to know before taking the BCAAs?

The use of BCAAs should be under close medical supervision during pregnancy and the subsequent breastfeeding period.

The same attention should also be maintained in cases of hepatic encephalopathy, large burns, extensive trauma, renal insufficiency, severe liver disease and neurodegenerative diseases such as amyotrophic lateral sclerosis.