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Essential Amino Acids- Summary Guide

This easy guide will provide you with a breakdown of what all the essential amino acids are, how much we should consume and the roles of each one.

Amino acids are categorised into 2 (and sometimes 3) groups, essential and non-essential amino acids. The names can be misleading as all the amino acids are required for the body to function!

The essential amino acids (EAAs) consist of nine amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylethylamine, threonine, tryptophan, and valine. They are called essential because our bodies need them to function properly but cannot make them, so they must be consumed from the diet, via food, beverage, or supplement sources. 

There is also an additional group called conditionally essential amino acids where some non-essential amino acids are required in larger intakes at certain stages of life, such as during pregnancy.

Amino Acid categories

Essential amino acids- must come from the diet Conditionally essential amino acids (may become essential when pregnant or during ill health) Non-essential amino acids- the body can make them in healthy people
Histidine Arginine Alaine
Isoleucine* Asparagine Arginine
Leucine* Glutamate Aspartate
Lysine Glycine Cystine
Methionine Proline Glycine
Phenylalanine Serine Ornithine
Threonine Tyrosine Proline
Tryptophan   Serine
Valine*   Tyrosine

Branch chain amino acids (BCAA) – *

What are the branch chain amino acids (BCAA’s)?

BCAA refers to three essential amino acids: leucine, isoleucine, and valine. They differ from the other essential amino acids because of their ‘branched-chain’ structure. (A branched-chain amino acid is an amino acid having an aliphatic sidechain with a branch). BCAAs do a good job at stimulating protein synthesis but the process is accelerated when combined with all the EAAs to complete the recovery process with more research backing up the move from BCAA to EAA supplementation.

How much we need – adult essential amino acid requirements.

  Adult amino acid needs (mg/kg of body weight) Examples need for 70kg heathy adult Adult minimum requirement (mg/g) of dietary protein needs
Histidine 10 210-350 22
Isoleucine 20 1400 18
Leucine 39 2730 25
Lysine 30 2100 22
Aromatic amino acids total (phenylalanine and tyrosine) 25 Individual values not est. 1750 25
Sulphur amino acids total Cysteine Methionine 15 4.1 10.4 1050 287 728 24
Threonine 13 910 13
Tryptophan 4 280 6
Valine 26 1820 18

So, what are the roles of the essential amino acids?

Each amino acid has multiple specific roles in the body, with many reactions requiring a combination of amino acids working together at once. Imagine your body is turning over metabolic processes 24/7, 365 days a year.The body can make the non-essential amino acids via metabolic processes. But the essential amino acids must come from the daily diet as they cannot be made by the body.

The body turns over numerous times more protein than what is consumed macro-wise, indicating that reutilisation of amino acids is a major characteristic of protein metabolism. However, the process of recapturing or recycling amino acids is not completely efficient, as the amino acids are used up as well as lost at varying rates due to demand and breakdown via oxidative catabolism.

Therefore a ‘top-up’ of the amino acids has shown to be a great method to prevent a decreased rate of the bodies reactions and processes. Amino acids are also lost in sweat, suggesting an increased need in hotter environments, intense training and those limiting nutrient intake for short periods for competition purposes.

Lifestyle places increased demands on the amino acid turnover rate; simply, if you train more you will need more!

Amino acids rely on each other to complete reactions, and if there is an amino acid missing or at lesser quantity than required the reaction is halted; in terms of muscle protein synthesis, the rate of recovery is inhibited.

But the essential amino acids are not just about muscle recovery and growth, but for many fundamental processes such as hormone production, neurological function, the immune system, antioxidant and vitamins and mineral utilisation, and many more.

To demonstrate the roles, and cross-over of the amino acids required the table below lists the key functions and the main food sources.

These small little units are the foundations of the human body, enabling and ensuring health, optimising performance and essential for life.

To demonstrate the roles and cross-over of the amino acids required in the body the table below lists the key functions and the main food sources:

Isoleucine (Ile) -Blood-sugar regulation
-Growth and repair  
-Muscle metabolism (heavily concentrated in muscle tissue).
-Important for immune function, hemoglobin production and energy production.
-One of the three branch chain amino acids
Dairy Eggs
Leucine (Leu) -Blood-sugar regulation
-Growth and repair of muscle tissue
-Hormone production
-Wound healing
-Energy regulation
-Critical for protein synthesis & muscle repair
-Produces growth hormones
-One of the three branch chain amino acids 
Beef Dairy Eggs
Almonds Brown rice Lentils
Valine (Val) -Growth and repair of muscle tissue
-Energy regulation
-Niacin production
-One of the three branch chain amino acids
Beef Dairy Eggs
Grains Mushrooms Nuts
Lysine (Lys) -Development and regulation of collagen, antibodies
-Growth and repair 
-Protein synthesis, hormone and enzyme production and the absorption of calcium
Beef Dairy Eggs
Lima beans Baked beans
Potatoes Soy
Methionine (Met) -May prevent arterial fat build up
-Promotes collagen synthesise 
-Necessary for tissue growth and the absorption of zinc and selenium
Beef Dairy Eggs
Lentils Onions Soybeans
Phenylalanine (Phe) -Neurotransmitter
-Increase blood levels of noradrenaline, adrenaline and dopamine
-Structural function of protein and enzymes and the production of other amino acids
Dairy Almonds
Peanuts Seeds
Threonine (Thr) -Antibody production
-A principal part of structural proteins such as collagen and elastin, that are important components of the skin and connective tissue
-Fat metabolism and immune function
Beef Dairy Eggs
Beans Nuts
Tryptophan (Trp) -Precursor for serotonin
-Niacin production
-Maintains proper nitrogen balance and is a precursor to serotonin, a neurotransmitter that regulate appetite, sleep and mood
Beef Dairy Eggs
Barley Brown rice
Peanut Soybeans
Histidine (His) -Growth Tissue repair Histamine development (neurotransmitter that is vital to immune response)
-Critical for maintaining the myelin sheath, a protective barrier that surrounds your nerve cells Sexual function and circadian rhythm
Pork Poultry
Rice Wheat

As you can see the EAA’s all serve a vast array of essential functions in the body.

Food sources that are abundant in EAAs include beef, lamb, pork, tuna, poultry, eggs, yogurt, salmon, soy, buckwheat, and quinoa, to name a few. EAAs play a variety of roles in the body, including serving as building blocks for tissue growth. 

Natalie Rouse.
Nutritional Research Scientist
Bsc(hons), MRes, MSc RNutr