Inside Our Food

9 Essential Amino Acids | Food Sources to Find Them

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 has 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, their roles, and where to find them in food. Brace yourself for some serious scientific terminology:

1. Phenylalanine

Without sufficient phenylalanine, your body could experience cognitive dysfunction, depression, and appetite loss.¹

Its 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 yoghurt. For every 100g of beef, you would have obtained about 154% of the recommended dietary intake.²
Plant-based options include tofu, pumpkin seeds, peanuts, wheat germ, quinoa, wild rice, and certain seeds and nuts. On average, for every 100g of firm tofu eaten, expect to get around 95% of the recommended dietary intake of Phenylalanine

2. Threonine

Threonine plays a key role in maintaining healthy skin and teeth. Since threonine is found largely in the central nervous system, studies have shown that it can help treat different types of depression.⁴

Here’s how it interacts in the body:

Once in the body, threonine changes into a chemical called glycine. Glycine helps 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, and 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, 100g of roasted soybeans also gives you around 165% of your recommended dietary intake of threonine.⁵

3. Tryptophan

Consuming enough tryptophan could potentially aid in regulating food cravings.⁶

Its 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 a precursor to melatonin, a hormone that helps regulate our sleep. As many of us know, good 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, yoghurt, 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 lot of tryptophan. For every 100g of seeds, 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

4. Methionine

Methionine helps with metabolism and detoxification.

Its 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, people can be more susceptible to arthritis, damaged tissue, and have trouble healing.⁸
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.⁹

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 methionine intake.
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.¹⁰

5. Lysine

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.¹¹

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.¹²

6. Histidine

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 vital to immune response, digestion, sexual function, and sleep-wake cycles.¹³
It also maintains the myelin sheath.

Histidine food sources

Excellent sources of histidine include apples, pomegranates, alfalfa, beets, carrots, celery, cucumber, garlic, radish, and spinach. 100g of dried bananas will provide you with around 48% of the recommended daily intake of histidine.¹⁴

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, but they also help to reduce fatigue.¹⁵

7. Valine

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 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.¹⁶

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 the make), you will get about 26% of the recommended daily intake. Even a cup of milk would give you about 60% of your recommended daily valine intake. ¹⁷

8. Leucine

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 signalling 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.¹⁸

Leucine food sources

You can find leucine in animal sources like cheese, beef, lamb, poultry, gelatin, and collagen. You get about 75% of the 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.¹⁹

9. Isoleucine

Isoleucine has also been 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 yoghurt.²¹
Plant-based sources include oats, lentils, spirulina, sunflower and sesame seeds, and seaweed. For 100g of wheat, you get about 16% of the recommended daily intake of isoleucine.

Amino Acid Daily Recommendations

Estimating the daily requirements for amino acids is challenging. However, the World Health Organization has created a list of the recommended daily intakes of these essential amino acids.²² By eating a healthy diet rich in vegetables, fruits, and protein, you should be able to reach your daily recommended amount of essential amino acids.