The 9 Essential Amino Acids: What They Do & Where to Get Them

If you have ever been in high school biology or you have friends that are fitness enthusiasts, bodybuilders, or weightlifters, you’ve probably heard of amino acids. In fact, you’ve probably been told more than once that these are the building blocks of protein.

Since amino acids are the building blocks of protein- which is one of the three macronutrients that make up the bulk of the human diet- it makes sense that bodybuilders love them so much. After all, protein is critical for muscle mass.

Even if you don’t plan to get ripped, you can still benefit from amino acids. It’s important to note that there are a total of 20 amino acids, and 9 of them are “essential”. The reason they are considered essential is that they are required for a wide variety of biological processes.

In this article, we’ll explore the 9 essential amino acids and what they do for you.

What is the Difference between Essential and Non-essential Amino Acids?

When you consume protein, your body breaks it down into amino acids, which are re-used to make the proteins needed by the body. One way to think of it is this: amino acids are train cars and protein is the train.

While it’s true that you do need all 20 amino acids to function, your body naturally produces 11 of them, so they are considered “nonessential” amino acids. There are some that are considered conditionally essential, which means they’re nonessential, except for in circumstances such as stress or illness.

However, the 9 essential amino acids can only be obtained from food. Your body does not naturally produce these.

9 Essential Amino Acids: What They Do & Where to Get Them

Before we get into discussing each one, it’s important to note that the 9 essential amino acids have their own unique properties. For example, some of them are important for the development of muscle, while others are more involved in mood regulation or production of collagen. Some physicians are finding success with using specific amino acids for patients who have anxiety or metabolic syndrome.

Animal proteins are considered “complete” proteins, meaning you can get fairly high levels of all 9 essential amino acids. However, it is possible to obtain them from plant-based foods. It’s important to note though, most of the plant-based foods do not contain all 9 of the essential amino acids, at least not in adequate proportions. Still, it’s possible for those who prefer a vegan or vegetarian diet to get what they need by consuming a variety of plant proteins throughout the day.

Below, we’ll take a closer look at each of the 9 essential amino acids, along with the role they play and the best foods to get them from.


The first one we’ll look at his histidine. Your body needs this for the growth/repair of tissue, specifically to maintain the myelin sheaths. Research indicates that it protects tissues from damage due to radiation and facilitates the removal of heavy metals from the body.

It has been shown to have antioxidant and anti-inflammatory properties and some research indicates that it protects against chronic disease. It is a precursor to histamine, a neurotransmitter involved in immune functioning and the production of red and white blood cells.

Where to get it:

Animal-based sources: beef, chicken, cheese, eggs, milk, pork, salmon, tuna, turkey, yogurt

Plant-based sources: beans, brown rice, lentils, peanuts, pumpkin seeds, quinoa, spirulina, soybeans, sunflower seeds, tofu, wheat germ, wild rice


The second is isoleucine, which is one of the three BCAAs used by the body to facilitate the repair and growth of muscle. In addition, it is involved in the formation of blood clots and critical for the production of hemoglobin, which carries oxygen through the body. It facilitates the use of glucose during workouts, which regulates blood sugar and energy levels.

Where to get it:

Animal-based sources: beef, cheese, cod, eggs, haddock, lamb, milk, pork, poultry, tuna, yogurt

Plant-based sources: beans, dried spirulina, lentils, oats, seaweed, sesame seeds, soybeans, sunflower seeds


The third essential amino acid we’ll look at is leucine, which is another of the three BCAAs used by the body for the growth and repair of muscle. There is some research that indicates it enhances strength performance and is believed to be the most important amino acid when it comes to increasing muscle mass because it seems to be primarily responsible for activating mTOR, which is a signaling pathway responsible for muscle protein synthesis.

Also, leucine facilitates the production of growth hormones, promotes healing of bones, skin, and muscle tissue following severe stress or trauma, and also facilitates the release of insulin, which regulates energy levels and blood sugar.

Where to get it:

Animal-based sources: beef, cheese, collagen, gelatin, lamb, pork, poultry, shrimp, tuna

Plant-based sources: almonds, beans, brown rice, corn, lentils, peanuts, pistachios, pumpkin seeds, quinoa, soybeans, spirulina, sunflower seeds, wheat germ


The fourth essential amino acid is lysine. It helps with the production of a variety of antibodies, enzymes, and hormones. It also plays a critical role in your immune system and offers antiviral properties. In fact, some research indicates that it may protect against herpes by improving the nutrient balance in the body to slow the growth of the virus.

It has also been proven that lysine, along with proline (another amino acid) and vitamin C are required for the production of collagen. Finally, research shows that it can help with mental health as well. One study revealed that supplementing with lysine and arginine reduces cortisol levels and anxiety.

Where to get it:

Animal-based sources: beef, cheese, collagen, eggs, gelatin, lamb, pork, poultry, shrimp, tuna

Plant-based sources: beans, lentils, oats, pistachios, pumpkin seeds, quinoa, soybeans, spirulina, wheat germ


The fifth essential amino acid is methionine, which is a sulfur-containing compound. The sulfur acts as an antioxidant in the body, protecting against damage from free radicals. It also facilitates the removal of heavy metals from the body. Research also indicates that it ensures healthy liver function. In addition to protecting against free radicals, it also improves appearance by improving tone and elasticity of skin and strengthening nails and hair.

Even with all those benefits, it’s important to note that too much methionine can cause atherosclerosis, which is a condition characterized by fatty deposits in your arteries.

Where to get it:

Animal-based sources: beef cheese, eggs, lamb, milk, pork, poultry, salmon, shrimp, tuna, yogurt

Plant-based sources: beans, Brazil nuts, lentils, peanuts, quinoa, spirulina, soybeans, tofu, wheat germ


The sixth essential amino acid is phenylalanine, which is involved in the creation of other amino acids, such as tyrosine. The body uses tyrosine to regulate mood/emotional response through the production of epinephrine, dopamine, and norepinephrine.

One study revealed that phenylalanine is important in treating the symptoms of Parkinson’s disease, due to its capacity to synthesize dopamine, norepinephrine, and tyrosine. In addition, researchers have looked at its antidepressant properties– but more research is required to confirm.

Where to get it:

Animal-based sources: beef, cheese, collagen, eggs, gelatin, lamb, pork, poultry, salmon, tuna, yogurt

Plant-based sources: almonds, brown rice, cashews, oats, peanuts, pistachios, pumpkin seeds, quinoa, spirulina, soybeans, tofu, wheat germ, wild rice


The seventh essential amino acid is threonine, which is involved in producing collagen and elastin. It’s also present in high concentrations in your central nervous system, and researchers indicate that it may reduce spasticity symptoms in patients who have multiple sclerosis, as well as relieve mild depression and anxiety.

It also is involved in establishing a healthy digestive tract and gut because it produces the mucus layer that covers the digestive tract. Along with serine, threonine is involved in the functioning of T-cells, to maximize immune systems and it prevents the buildup of fat in the liver.

Where to get it:

Animal-based sources: beef, cheese, collagen, gelatin, lamb, pork, poultry, salmon, shrimp, tuna

Plant-based sources: almonds, beans, cashews, flaxseeds, lentils (peas), peanuts, pistachios, pumpkin seeds, spirulina, soybeans, sunflower seeds, tofu, wheat germ


The eighth essential amino acid is tryptophan. It is involved in the production of serotonin, which regulates mood, pain, appetite, and sleep and has a natural sedative effect. It is also a precursor to melatonin, which regulates sleep/wake cycles. This is why you feel sleepy after a big holiday meal that includes turkey.

Research indicates that it relieves symptoms of premenstrual syndrome and low levels are related to anxiety, depression, and mood swings. It also supports the production of niacin.

Where to get it:

Animal-based sources: beef, cheese, eggs, lamb, pork, poultry, salmon, shrimp, tuna

Plant-based sources: almonds, beans, cashews, chia seeds, lentils, oats, pistachios, pumpkin seeds, soybeans, spirulina, tofu, wheat germ


The final essential acid is valine. This is the third of the three BCAAs that are used by the body for growth and repair of muscles. It has also been shown to regulate blood sugar by transporting glucose to muscles- which maintains energy levels and reduces fatigue.

It has also been shown to maintain mental and physical stamina, as well as support emotional calm. In addition to the other two BCAAs, it has been proven to be helpful in the treatment of liver disease.

Where to get it:

Animal-based sources: beef, cheese, collagen, eggs, gelatin, lamb, milk, pork, poultry, salmon, tuna, yogurt

Plant-based sources: beans, broccoli (cooked), brown rice, cashews, lentils, mushrooms, oats, pistachios, pumpkin seeds, quinoa, soybeans, spirulina, sunflower seeds, wheat germ, wild rice

Is it necessary to supplement with essential amino acids?

While this is a great question, the more appropriate one would be this: does your diet include enough protein?

If the answer is no, you’re likely not getting enough of the 9 essential amino acids. If this is the case, add more protein from the animal and plant sources listed above. If you’re vegan or vegetarian, or you’re not sure you’re getting the protein you need, supplementation with a high quality protein powder may be necessary. You can add this to your baked goods, smoothies, oatmeal, and more.

Whey protein is considered a complete protein. Many of the vegan powders are too, since they are either made with soy (which is a complete plant protein) or with a variety of plant sources.

That being said, it is possible to get all 9 essential amino acids through your diet regardless of whether your diet is animal-based or plant-based. Supplementation is not always necessary.

What about BCAAs?


If you’re into fitness, you’ve likely heard someone mention BCAAs at some point. This is three of the essential amino acids that seem to play a substantial role in muscle maintenance and research indicates that together they activate certain enzymes that facilitate the growth of muscle. The term “branched-chain” refers to their structure.

However, BCAAs do also have other purposes, including fighting fatigue as well as interfering with the transportation of relaxation amino acids such as tryptophan. This keeps you from getting too sleepy.

The good news is that unless your medical provider suggests it, you really don’t need to take a BCAA supplement, as long as you are eating well. BCAAs are naturally found in the animal- and plant-based sources listed above for each one (isoleucine, leucine, and valine).



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