Amino acids are grouped into three categories – essential, nonessential, and conditional. The group to which a specific amino acid belongs depends on where the body obtains it. There are 20 amino acids the body needs to function properly, 11 of which it can produce itself.  

Nonessential amino acids are those that the body naturally produces throughout the day whether you eat food that contains them or not. These include alanine, asparagine, aspartic acid, and glutamic acid. 

Conditional amino acids are produced only under specific circumstances, typically when the body is fighting off an illness or dealing with stress. These include arginine, cysteine, glutamine, tyrosine, glycine, proline, and serine. 

Of the 20 amino acids the body needs, nine are known as essential amino acids which the body is unable to make.  

THE NINE ESSENTIAL AMINO ACIDS 

1. Phenylalanine: is needed to produce the brain’s chemical messengers, including dopamine, epinephrine, and norepinephrine. It’s also important to produce other amino acids. 

• High content foods: Meats and dairy, fish, beans, and whole grains. 

2. Valine: is involved in muscle growth, tissue regeneration and making energy 

• High content foods: Meats and dairy, fish, beans, and seeds. 

3. Tryptophan: helps maintain the body’s correct nitrogen balance. It also helps make serotonin which regulates mood, appetite, and sleep. 

• High content foods: Meats and dairy, fish, beans, and whole grains. 

4. Threonine: plays an important role in collagen and elastin. Proteins which provide structure to skin and connective tissue. They also help with forming blood clots, which help prevent bleeding. Threonine plays an important role in fat metabolism and the immune function too. 

• High content foods: Meats and dairy, fish, beans, and seeds. 

5. Isoleucine: is involved with the body’s muscle metabolism and immune function. It also helps make haemoglobin and regulate energy. 

• High content foods: Meats and dairy, fish, whole grains, seeds. 

6. Methionine: helps with the body’s tissue growth, metabolism, and detoxification. Methionine also helps with the absorption of essential minerals, including zinc and selenium.  

• High content foods: Meats and dairy, fish, beans, and nuts. 

7. Histidine: helps make a brain chemical called histamine which plays an important role in the immune function, digestion, sleep, and sexual function. 

• High content foods: Meats and dairy, fish, beans, seeds. 

8. Leucine: helps the body make protein and growth hormones. It also helps grow and repair muscle tissue, heal wounds, and regulate blood sugar levels. 

• High content foods: Meats and dairy, fish, tofu, and seeds. 

9. Lysine: is involved in the production of hormones and energy. It’s also important for calcium and immune function. 

• High content foods: Meats and dairy, fish, tofu, and beans. 

Foods that contain all nine essential amino acids are called complete proteins. These foods include beef, poultry, fish, eggs, dairy, soy, quinoa, and buckwheat. 

“For most physiological states in a healthy adult, the nine amino acids are the only essential amino acids,” said Lopez et al. in Biochemistry, Essential Amino Acids (published in StatPearls online). “However, amino acids like arginine and histidine may be considered conditionally essential because the body cannot synthesise them in sufficient quantities during certain physiological periods of growth, including pregnancy, adolescent growth, or recovery from trauma.