Amino acids are known as the building blocks of proteins. While the body needs 20 different amino acids to grow and function properly, there are 9 essential amino acids that your body can’t produce without food.

Each of the 9 essential amino acids have unique functions. Some essential amino acids are important for muscle development, while others help regulate mood. So, even though we may not all be fitness fanatics looking to pack in the amino acids to help build muscle mass, everyone can benefit from eating a healthy diet with the right essential amino acids. Here are 9 essential amino acids, what roles they play, and where to find them in food. Brace yourself for some serious scientific terminology:


Without sufficient phenylalanine your body could experience cognitive dysfunction, depression, and appetite loss.1 It’s role in the body includes:

  • Phenylalanine helps to create other amino acids like tyrosine. Tyrosine is used to help produce neurotransmitters such as dopamine (the happy chemical).
  • Phenylalanine also helps form other important brain chemicals that regulate your adrenaline (your body’s fight or flight response).
  • Phenylalanine is a precursor for thyroid hormones, which regulate your metabolism.

Phenylalanine food sources

  • Animal sources include beef, lamb, pork, poultry, cheese, eggs, and yogurt. For every 100g of beef, you would have obtained about 154% recommended dietary intake.2
  • Plant-based options include tofu, pumpkin seeds, peanuts, wheat germ, quinoa, wild rice, as well as certain seeds and nuts. On average, for every 100g firm tofu eaten, expect to get around 95% of the recommended dietary intake of Phenylalanine


Threonine plays a key role for maintaining healthy skin and teeth. Since threonine is found largely in the central nervous system, studies have shown that it can be helpful in treating different types of depression. Here’s how it interacts in the body:

  • Once in the body, threonine changes into a chemical called glycine. Glycine help produce elastin, collagen, and muscle tissue.
  • When combined with methionine (another amino acid), glycine helps process fatty acids and helps prevent liver failure.3

Threonine food sources

  • Animal sources of threonine include lean beef, lamb, pork, collagen, gelatin, cheese. For every 100g of lean beef or lamb there’s about 165% of your recommended dietary intake.5
  • Plant based sources include tofu, sunflower seeds, flaxseeds, wheat germ, cashews, almonds, lentils, and pistachios. The richest plant-based source for threonine is soya products, with 100g of roasted soybeans it also gives you around 165% of your recommended dietary intake of threonine.


Consuming enough tryptophan could potentially aid in regulating food cravings. It’s role in the body includes:

  • Tryptophan is crucial to serotonin production. Serotonin helps regulate appetite, sleep, mood, and pain, and also acts as a natural sedative.
  • It’s also known to be a precursor to melatonin, a hormone which helps regulate our sleep. As many of us know, having a good amount of sleep is crucial for your body’s immune response and nervous system function.

Tryptophan food sources

  • Animal sources include dark chocolate, milk, cheese, turkey, red meats, yogurt, eggs, and fish.
  • Plant based sources include chickpeas, pepitas, spirulina, bananas, and peanuts. However, seeds and nuts (specifically pumpkin and squash seeds) also have a large amount of tryptophan. For every 100g of seeds there’s you’ll be getting roughly 206% recommended dietary intake of tryptophan. For 100g of cheese (reduced fat mozzarella) you should be at around 204% of your recommended dietary intake.7


Methionine helps with metabolism and detoxification. It’s role in the body includes:

  • The sulfur found in methionine acts as an antioxidant for the body by protecting the cells from free radical damage. It also helps remove other heavy metals like lead and mercury in the body. Without sufficient sulfur in the body, people can be more susceptible to arthritis, damaged tissue, and have trouble healing.
  • Methionine also helps to break down fat and prevent fatty deposits in the liver. Too much of this amino acid though, can lead to atherosclerosis, or fatty deposits in the arteries.

Methionine food sources

  • Animal sources include tuna, salmon, shrimp, beef, and lamb. For every 100g of tuna you will find 122% of your recommended daily intake of methionine.
  • Plant-based sources include brazil nuts, soybeans, tofu, beans, lentils, wheat germ, and spirulina. About 100g of brazil nuts would give you 154% of your recommended daily intake.


Lysine is responsible for muscle repair and growth. How it functions in the body:

  • By producing a variety of hormones, enzymes and antibodies, lysine helps build a healthy immune system.
  • It also has a crucial role in the production of collagen. Collagen is the most abundant protein in the body that gives structure to ligaments, tendons, skin, hair, cartilage, and organs.
  • Lysine is also used to help the body absorb calcium, iron, and zinc. These are important minerals for immune health.

Lysine food sources

  • Red meat provides the most amount of lysine. For every 100g of beef, expect 157% of your recommended daily intake for lysine.
  • Plant-based sources include lima beans, avocados, dried apricots and mangoes, beetroots, leeks, potatoes, and peppers.


Histidine helps facilitate growth, the creation of blood cells, and tissue repair. How it functions in the body:

  • Ultimately, the body metabolizes histidine into histamine. Histamine is a neurotransmitter that is vital to immune response, digestion, sexual function, and sleep-wake cycles.
  • It also maintains the myelin sheath.

Histidine food sources

  • Great sources of histidine include apples, pomegranates, alfalfa, beets, carrots, celery, cucumber, garlic, radish, and spinach. For 100g of dried bananas will provide you with around 48% recommended daily intake of histidine.

Fun Fact: The following three essential amino acids are known as branched-chain amino acids (BCAAs). They make up a large portion of the body’s total amino acid pool (about 35-40%). Not only can BCAAs help build muscle protein and produce energy, they also help to reduce fatigue.15


Valine, one of the three BCAAs, is often used in supplement form with other BCAAs to build muscle mass in athletes. It’s role in the body:

  • Stimulates muscle growth and regeneration, and is involved in energy production.
  • Studies have concluded that valine can also help stimulate activity, while maintaining mental and physical stamina. That’s because it helps support the central nervous system by keeping it calm.

Valine food sources

  • Valine is found most abundantly in red meats, dairy products, soy products, mushrooms, and peanuts. For about 100g of low-fat yogurt (depending on make) you will get about 26% recommended daily intake. Even a cup of milk would give you about 60% of your recommended daily intake of valine. 


Leucine is critical for protein synthesis and muscle repair. It has been argued that it is the most important amino acid to build muscle mass because it helps activate a signaling pathway that is responsible for stimulating protein synthesis. How it functions in the body:

  • It helps regulate blood sugar levels, stimulates wound healing and growth hormones.
  • Leucine also helps to promote healing of muscles following trauma, or severe levels of stress.

Leucine food sources

  • You can find leucine in animal sources like cheese, beef, lamb, poultry, gelatin, and collagen. You get about 75% recommended daily intake of Leucine for every 100g of chicken consumed.
  • Plant-based sources include quinoa, sunflower seeds, pistachios, peanuts, corn, wheat germ, and brown rice. Spirulina is a fantastic source of leucine, giving around 181% of your recommended daily intake per 100g.


Isoleucine is also found to help blood clot formation.20 How it functions in the body:

  • Isoleucine is heavily concentrated in muscle tissue, and plays a vital for muscle metabolism, immune function, hemoglobin production and energy regulation.

Isoleucine food sources

  • Animal-based sources include beef, tuna, cod, haddock, and yogurt.21
  • Plant-based sources include oats, lentils, spirulina, sunflower and sesame seeds, and in seaweed. For 100g of wheat, you get about 16% recommended daily intake of isoleucine.


Estimating the daily requirements for amino acids is challenging, however the World Health Organization has created a list of the recommended daily intake of these essential amino acids. By eating a healthy diet rich of vegetables, fruits, and protein you should be able to reach your daily recommended amount of essential amino acids. 

Amino AcidDaily Recommendations (mg/kg of body weight)
Histidine10 mg
Isoleucine20 mg
Leucine39 mg
Lysine30 mg
Methionine10.4 mg
Phenylalanine25 mg
Threonine15 mg
Tryptophan4 mg
Valine26 mg

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