Week Two : The importance of the essential amino acids in a diet

aminoacids gym

Amino acids are the building blocks for protein and a life necessity for humans and animals. Amino acids are bonded with nitrogen and form proteins and nitrogen is the end product of protein digestion. Amino acids are the primary building blocks of your muscles, bones, enzymes and many hormones. We cannot live without protein and as long as we get sufficient protein from animal and or plant based diets, it is fine.

There are 22 amino acids where eight is classified as essential. The essential amino acids cannot be manufactured by the body and must be supplemented by food and supplements. The non-essential amino acids can be synthesised by the body if all the essential ones are available. Histidine is only essential for infants and children.

Essential amino acids and their unique functions

1. Tryptophan (essential)

It is used by the brain with vitamin B6, niacin and magnesium to produce serotonin.


  • Assist in sleep
  • Can reduce pain sensitivity
  • Anti-depressant
  • Reduce anxiety and tension
  • Can assist in alcohol withdrawal symptoms

Best foods

  • Cottage cheese
  • Milk
  • Meat
  • Fish
  • Turkey
  • Bananas
  • Dried beans
  • Peanuts
  • All protein rich foods

2. Phenylalanine (essential)

Phenylalanine is an essential neurotransmitter. In the body, it is converted into noradrenaline and dopamine.


  • Reduce hunger
  • Increase sex drive
  • Improve memory
  • Improve mental alertness
  • Assist in relieving depression

Best foods

  • All protein rich foods
  • Soy products
  • Cottage cheese
  • Dry skim milk
  • Almonds
  • Peanuts
  • Lima beans
  • Pumpkin
  • Sesame seeds

Please note it can increase blood pressure

3. Lysine (essential)

This is a very important amino acid in the complete protein and is used for growth, tissue repair and the production of antibodies, hormones and enzymes.


  • Prevents and helps herpes infection
  • Enhance concentration
  • Utilize fatty acids needed for energy production
  • Assist in fertility problems

Best foods

  • Fish
  • Milk
  • Lima beans
  • Meat
  • Cheese
  • Yeast
  • Eggs
  • Soy
  • All protein-rich foods


Tiredness, concentration problems, blood shot eyes, nausea, dizziness, hair loss and anaemia can be linked to a lysine deficiency.

4. Methionine (essential)

This is also a sulphur-containing amino acid.


  • Can help in schizophrenia by lowering levels of histamine
  • In combination with choline and folic acid it has protective properties against certain tumours
  • Deficiency can cause oedema and possible infection
  • Deficiencies have been linked to arthrosclerosis and hair loss

5. Histidine (only essential for infants and children)

An unbalanced diet or too much stress can lead to a deficiency, which can cause growth disruptions or rheumatic arthritis in adults.


Histidine can be converted into various substances, including histamine, glutamate and haemoglobin.  It is involved in various metabolic reactions and hence ensures indirectly the oxygen supply to all the organs and tissues. It is a building block for molecules containing iron, like ferritin. This function is important, because it ensures a sufficient energy supply in the cells and can detoxify the body of heavy metals through its ability to combine with them.

Histidine regulates the pH-values of the blood, supporting the healing of wounds, and the regulation of growth and natural repair mechanisms. Without Histidine, growth processes would be interrupted and a lack of this amino acid can lead to slow development and the regeneration of tissue. A deficiency can lead to the inflammation of the skin and mucous membranes and a slower recovery after operations or surgical procedures.

Histidine is also necessary for the formation of the myelin sheath, which surrounds all nerve cells and protects them from damage, and can be used to prevent certain degenerative conditions, such as Alzheimer’s and Parkinson’s. This semi-essential amino acid is involved in in the synthesis of red and white blood cells, and so influences the activity of the immune system, as leukocytes play a large role in combating pathogens.

Histidine can protect the body from radiation damage, by binding itself to the damaging molecules, therefore eliminating them. For this reason, a specially designed preparation containing Histidine can be administered before medical treatment where ionising radiation is involved, to protect the body from the direct and indirect effects of radiation.

Histidine can have a therapeutic effect in cases of inflammation and can therefore be used in the treatment of arthritis and to help reduce the symptoms of allergies.

Medical uses for Histidine

  • This amino acid can lower the blood pressure.
  • Histidine is important in the treatment of chronic kidney failure. A low concentration of Histidine in the blood plasma increases the inflammatory activity of the body
  • Histidine, in combination with zinc can be effective against colds

6. Branched Chain Amino Acids or BCAAs: Valine, Leucine and Isoleucine (essential)

  • BCAAs enhance muscle protein synthesis for greater muscle hypertrophy (growth) and maintenance of lean muscle mass during non-training
  • Leucine-enriched BCAAs mixtures enhance muscle building for older trainees who would like to put on muscle.
  • BCAAs increase fat burning (Leucine) and glucose tolerance (Isoleucine)
  • BCAAs improve hormone balance for strength, power and endurance by increasing testosterone and decreasing cortisol and also reduce inflammation
  • BCAAs may improve strength development with training because of increasing neuromuscular coordination.
  • BCAAs enhance strength endurance and decrease fatigue and delay fatigue and tiredness by inhibiting Tryptophan receptors in the brain
  • BCAAs preserve the integrity of muscle fibres
  • BCAAs reduces muscle degradation by protecting lean muscle tissue.
  • BCAAs improves insulin health and metabolic rate
  • BCAAs have anti-ageing properties by increasing the formation of new mitochondria and thus reduce age related muscle loss
  • BCAAs improve cognition, by enhancing the effect on neurotransmitters and glutamate synthesis

Foods with large amounts of BCAAs

  • Beef (approx. 1690 mg / 100 g)
  • Raw salmon (approx. 1615 mg / 100 g)
  • Eggs (approx. 1090 mg / 100 g)
  • Wheat products (approx. 920 mg / 100 g)

Valine and Isoleucine are also included in meat and other animal produce

  • Dried peas (approx. 1160 mg / 100 g)
  • Walnuts (approx. 750 mg / 100 g) are suited for vegetarians with their high BCAA concentration

BCAAs are predominantly metabolised in the muscles and not in the liver. They are useful in treating protein tissue reducing conditions such as tumours, because they reduce the natural amino acid catabolism or break down. In chronic liver conditions, a sufficient supply of BCAAs is vital, because it can stop the transfer of potential harmful substances from the blood to the brain.

Leucine in particular plays a vital role in the generation and preservation of muscle tissue. It regulates the energy supply of the body and plays a part in the synthesis of glucose. Valine is very important in the biosynthesis of protein and the proper conversion of food into energy.

7. Threonine (essential)

It is essential for regulating protein balance in the body. Threonine is a precursor to serine and glycine. They are the two other amino acids necessary for muscle tissue production. Threonine is important in: supporting digestive function, immune system, liver and cardiovascular function and the central nervous system.

Threonine and the digestive system

A large portion of Threonine is absorbed in the upper part of the small intestine. This amino acid protects the digestive tract. Threonine is important in producing the mucus gel layer that covers the digestive tract. This mucus functions as a barrier to digestive enzymes that can damage the intestines. This amino acid is important for supporting healthy gut function.

Animal studies have found that a low threonine diet leads to digestive problems and a reduction in the immune function. This is possibly due to a decline in the gut mucus barrier. It also disrupts nutrient absorption.

Threonine and immune system support

Threonine helps to produce antibodies to boost the immune system. The thymus gland is responsible for synthesising infection-fighting T-lymphocytes (T-cells) and utilises this amino acid. Enough threonine is needed to support immune function is important to protect against diseases.

Threonine and liver health

Threonine works together with the methione and aspartic acid to support the liver to digest fatty acids and fats. With an insufficiency of threonine, the liver can become overwhelmed by fats and can result in liver failure.

Threonine and bone/connective tissue health

Collagen and elastin need threonine. Threonine is the precursor for serine and glycine. These amino acids are necessary to create these proteins. Collagen is a structural protein in the body and is vital for connective tissue formation and maintenance. Threonine helps to support strong and elastic muscles and connective tissue throughout the body. This amino acid can assist to accelerate healing of wounds and bones following injury.

Threonine and cognitive function

Threonine is in high concentrations in the central nervous system.

Threonine can help reduce some of the symptoms of Multiple Sclerosis, including a reduction in spasticity. It can also help to fight depression and can improve mental health.

Symptoms of Threonine deficiency

Digestion difficulties, emotional agitation, confusion and a fatty liver are common symptoms of a threonine deficiency. Vegans and strict vegetarians may want to consider a supplement because the highest concentrations of this amino acid are found in meat and dairy products.

Dietary sources of Threonine

This essential amino acid is found in fish, meat, meat products, dairy, eggs, carrots, and bananas. Nuts, beans, seeds and other vegetables do also contain threonine, but not in high concentrations.


  1. aminoacidstudies.org
  2. wikipedia.org
  3. aminoacid-studies.com
  4. The Vitamin Bible. Earl Mindell
  5. https://draxe.com/protein-deficiency/
  6. http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/high-protein-diets/faq-20058207
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