The Role of BCAAs and Glutamine in Muscle Growth, Recovery, Immunity and General Health

Branch Chain Amino Acids or BCAAS are the primary sources of protein and energy in muscles. Responsible for protein manufacture or protein synthesis they make up one third of muscle cell protein. BCAAs and glutamine are beneficial agents that replenish cells with several metabolic resources to keep the human body physiologically healthy and active.

Main Types of Branch Chain Amino acids

There are three main BCAAs known as essential amino acids. These are Leucine, Valine, and Isoleucine. The main reason for labeling them ‘essential’ is because they are not manufactured by the body. Your primary source of all three is from a regular diet. In body building and athletic sport, requiring a steady recommended source of BCAAS, and dietary supplements becomes necessary for improved protein synthesis and optimum performance.

The Main Role of Essential BCAAs


Leucine regulates protein and is responsible for a stable and healthy metabolic process with the production of energy. It also restricts protein breakdown resulting from muscle stress. The different roles of leucine are:

  • Protein synthesis: Leucine is a key regulator of protein synthesis, particularly in skeletal muscle activating the mTOR signaling pathway, increasing protein synthesis, and slowing down the degradation of muscle tissue.
  • Improves performance and aids in muscle recovery: Leucine is particularly important for muscle growth and repair, especially during periods of physical activity or recovery from injury. Studies have found how leucine contributes to both muscle growth and muscle recovery.
  • Regulation of blood sugar levels: Some studies have found how leucine can decrease blood sugar levels by stimulating insulin secretion. Research has also found how leucine supplementation can inhibit gluconeogenesis in liver when blood sugar levels are elevated.
  • Energy production: Leucine can be converted into acetyl-CoA, a key molecule in the citric acid cycle (also known as the Krebs cycle) which is responsible for generating energy in the form of ATP (adenosine triphosphate) in cells.
  • Immune function: Studies suggests that leucine is important for the adaptive immune response in which leucine plays a role in T cell activation

Top 10 Food Sources of Leucine

  • Canned Navy Beans
  • Cheese: Cottage Cheese (Paneer)/Ricotta Cheese
  • Seeds: Sesame/Pumpkin/Hemp seeds
  • Eggs
  • Lean red meat: Beef steak/Pork chops
  • Lean White meat: Chicken leg/Turkey /Tuna
  • Tofu
  • Milk


Isoleucine plays a similar role as Leucine critical in physiological functions of the whole body, such as growth, immunity, protein synthesis, fatty acid metabolism and glucose transportation. Isoleucine can improve the immune system, including immune organs, cells, and reactive substances.

Isoleucine even plays the role of an anti-oxidant. Antioxidants are elements that scavenge free radicals form the body. These are cancerous and disease-causing agents which forever plague and destroy healthy cells.

Top 10 Food Sources of Isoleucine

  • Lean chicken breast
  • Lean pork chops
  • Tuna/salmon/tilapia
  • Tofu/tempeh
  • Milk
  • Large white beans/pinto beans
  • Teff/quinoa
  • Squash/pumpkin seeds
  • Podded peas
  • Spinach


Valine metabolizes and improves energy, increases protein synthesis, improves growth hormone and like leucine it also prevents the loss of protein from muscle stress and strenuous workouts. Moreover, Valine contributes to neurological function and is involved in the synthesis of neurotransmitters such as gamma-aminobutyric acid (GABA), which plays a role in regulating neuronal excitability and is associated with relaxation and anti-anxiety effects. Valine is essential for mental focus, muscle coordination, and emotional calm where deficiencies can lead to insomnia and reduced cognitive function.

Valine plays a role in the repair and growth of tissues throughout the body, including muscle tissue. It is particularly important during periods of physical activity, recovery from injury, or growth phases such as infancy and adolescence. Moreover, valine has been found to be a precursor in the penicillin biosynthetic pathway.

Top 10 Food Sources of Valine

  • Lean beef steak
  • Lean chicken breast
  • Lean pork chops
  • Tuna
  • Tofu
  • Low fat yoghurt
  • Squash/pumpkin seeds
  • Podded peas
  • Navy beans
  • Oatmeal

BCAAS Are Abundant in Skeletal Muscle Tissue

All three BCAAS are found in abundance in skeletal muscle tissue because unlike most amino acids which are broken down in the liver, BCAAS are metabolized mostly in muscle tissue. This is why plasma levels of muscle tissue are found to have higher concentration of BCAAS than the rest of the body. Because of their unique metabolic feature, BCAAS are also more efficient in maintaining nitrogen balance, generating  ATP and the synthesis of glutamine, another important amino acid essential in healthy function and athletic performance. This is why there is a major association between BCAAs and glutamine in the body.

In a nutshell, since BCAAS promote protein synthesis, hence they are beneficial to muscle cells which rely mainly on protein for development and growth. The other element is the production of energy and glutamine required for muscle performance, immunity and a host of bodily function integral to good health.

BCAAS regulate blood sugar for production of energy

The activity of BCAAs takes place in muscles. During the metabolic process, BCAAs from plasma as well as the liver are constantly transported to muscle cells mainly skeletal muscle tissue. Besides the replenishment of protein, they regulate blood sugar levels during workouts and physical activity. This is done by stimulating the body’s ability to produce insulin which enables muscle tissue to absorb blood sugar for a constant source of energy.

Insulin as one should know is one of the most important elements in muscle building containing 51 amino acids. It plays an important role in providing energy to support all forms of muscular activity. Some studies have found how correct intake of BCAAS leads to improved insulin resistance while new studies have found excessive intake of BCAAS can actually be detrimental to health causing insulin resistance and type 2 diabetes.

The role of BCAAS in workout recovery

During periods of muscle fatigue and stress, the body calls upon its reserves of BCAAs for assistance. The release of BCAAS is a condition in which the body’s receptors halt the process of protein synthesis. Imagine what would happen if your protein reserves were halted during any strenuous physical activity. The result is fatigue, strain, and exhaustion. Once the BCAAs are pressed into action, protein synthesis is resumed leading to reduced muscle soreness and muscle recovery. Studies have found that while BCAAS may not entirely enhance athletic performance, they play a huge role in recovery and soreness.


BCAAs and glutamine are extremely important in athletic performance and sports nutrition. During periods of physical activity and workouts, BCAAs are constantly being burnt for the resources to increase activity. In skeletal muscle BCCAAs are catabolized and broken down to produce another important sub substance called Glutamine. Called a glycogenic amino acid, glutamine alongside BCAAs is an important factor in cell recovery, reduction of fatigue and improved levels of endurance.

How is glutamine produced

BCAAS are among the main precursors of glutamine synthesis helping the body produce glutamate and ammonia from nitrogen. Ammonia is a waste produce produced by bacteria in the intestines and your body’s cell during processing of protein. While most of it is excreted through the liver in the form of urea, some of it is used to combine with glutamate to produce glutamine. and glutamine

The main function of glutamine is to assist the body in post workout recovery reducing the effects of muscle wear and tear or aches and sprains. It is also beneficial to one’s immunity reducing chances of disease or respiratory infections. In conditions of injury and prolonged muscular stress, glutamine supplementation becomes necessary to provide the body with an increased source of the element.

Role of Glutamine in the body

  • Protein Synthesis: There is mixed debate whether glutamine indeed increases muscle protein synthesis. One study found how glutamine increased protein synthesis in isolated intestinal epithelial cells. Other studies have found how glutamine stimulates protein synthesis in skeletal muscle in rats. However, several studies have found how glutamine contributes to a reduction in muscle soreness and aids in muscle recovery.
  • Energy Production: Glutamine acts as a substrate for energy production, particularly in tissues with high metabolic demands such as the intestine, kidneys, and immune cells. It can be converted into glucose through gluconeogenesis, providing an energy source during periods of fasting, stress, or intense physical activity. Studies have explored glutamine as an anti-fatigue amino acid in sports nutrition.
  • Immune Function: Glutamine supports immune function by serving as a primary fuel source for rapidly dividing immune cells, such as lymphocytes and macrophages. It also plays a role in maintaining the integrity of the intestinal barrier, which is vital for immune defense against pathogens.
  • Maintaining Kidney acid base: Contributes to the production of ammonium to help maintain the kidney’s acid-base balance.
  • Intestinal Health: Glutamine is essential for maintaining the structural integrity and function of the intestinal mucosa. It helps to preserve gut barrier function, prevent intestinal permeability, and support the regeneration of intestinal epithelial cells, which is crucial for digestive health and nutrient absorption.
  • Nitrogen Transport and Storage: Glutamine serves as a carrier of nitrogen between tissues, aiding in the removal of excess ammonia from the body. Ammonia, a toxic byproduct of metabolism, is detoxified in the liver through the synthesis of urea, with glutamine providing the necessary nitrogen for this process.
  • Antioxidant Support: Glutamine possesses antioxidant properties, helping to neutralize harmful free radicals and reduce oxidative stress in the body. Glutamine’s antioxidant and anti-inflammatory properties may be considered as a potentially useful supplement for athletes.
  • Cellular Signaling: Glutamine serves as a precursor for the synthesis of other amino acids, neurotransmitters, and signaling molecules. It contributes to the regulation of various cellular processes, including gene expression, cell proliferation, and apoptosis (programmed cell death).

Why BCAA and glutamine supplementation is necessary in muscle building

During muscle building activity, BCAAS and glutamine are depleted. Moreover, BCAAS are constantly being broken down in muscle tissue for their resources conducive to protein and energy. Rigorous workouts especially utilize all such resources faster than production from a natural diet. This is where supplementation becomes necessary to maintain an effective source of BCAAS in the body. Generally, a dosage of 5-10 gms of glutamine per day for gut health and immunity is considered safe.

However, there is no shortcut that does not come with risks and speaking to a nutritionist or sports doctor about how much BCAAs and glutamine you need to take is necessary to avoid side effects from overdosage. While short-term use of supplements is likely safe, scientists are concerned about side effects from long term use.

Top 10 foods high in Glutamine

  • Fish and seafood
  • Red cabbage
  • Ribeye skirt steak
  • Pork tenderloin/pork chops
  • Chicken and turkey leg/breast
  • Hemp seeds/almonds/walnuts/flaxseeds/sunflower seeds
  • Oats
  • Lentils
  • Green peas
  • tomatoes

Concerning the role of BCAAs and glutamine in muscle building and workout recovery, one can conclude that BCAA supplementation is advantageous in providing the body as independent resource for replenishing BCAAS lost during oxidation from workouts. Although this also helps in stimulation of glutamine and alanine, supplementation of glutamine is an added benefit not only for muscle cell recovery but for overall improved health, improved immunity, and maximum body building performance. However, as mentioned, nothing comes without side effects and no dosage is a standard for all. It is always advisable to try and get your amino acids from a healthy diet. Where supplementation is necessary, a nutritionist or doctor is the best person to advise a suitable dose.