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Essential amino acids (EEA)

As we know, amino acids are the building blocks of proteins. There are 20 different amino acids that make up proteins, and they can be classified into two categories: essential and non-essential amino acids.

Essential amino acids are a group of nine amino acids that the human body cannot synthesize on its own and must be obtained through the diet. These amino acids are essential for the proper functioning of the body, including the growth, repair, and maintenance of tissues.

Essential amino acids play many important functions in the human body, including:

  • Protein synthesis: Essential amino acids are necessary for building and repairing muscle tissue, as well as for the synthesis of other important proteins in the body.
  • Energy production: Amino acids can be broken down and used as a source of energy by the body, particularly during periods of fasting or exercise.
  • Blood sugar regulation: Some amino acids, such as leucine and isoleucine, are involved in regulating blood sugar levels and promoting glucose uptake by cells.
  • Hormone production: Amino acids are used in the production of various hormones and neurotransmitters, including serotonin, dopamine, and melatonin.
  • Immune function: Amino acids are involved in the production of antibodies and other immune cells that help to protect the body against infections and diseases.
  • Wound healing: Essential amino acids are important for the repair and regeneration of tissue, including skin, bone, and muscle tissue.
  • Brain function: Amino acids are used in the production of neurotransmitters that are essential for brain function, including memory, cognition, and mood.

Nine essential amino acids

1. Lysine

Lysine plays a critical role in the formation of collagen, a structural protein that is essential for the health of skin, bones, and connective tissues. It also supports the immune system by promoting the production of antibodies and aiding in the absorption of calcium. It is very important for proper growth but also for the production of carnitine. This substance regulates fat metabolism and maintains an optimal level of cholesterol in the blood. Also, it helps the absorption of calcium, necessary for firm bones, and participates in the production of collagen. Lack of this essential amino acid causes osteoporosis, nausea, depression, and fatigue.

It is especially important for the growth and development of the skeleton in children. Elderly people and men have higher needs for lysine because amino acid is necessary for the creation of antibodies, hormones, and numerous enzymes.

Lysine is found in high-protein foods such as meat, poultry, fish, dairy products. For vegans beans are the best source of lysine. In addition to beans, there are also in lentils, chickpeas, soy, parsley, almonds, spirulina algae, and avocado.

2. Leucine

Unlike other amino acids that are metabolized in the liver, this amino acid is metabolized in the muscles. It is especially recommended for athletes because it reduces muscle damage during training and significantly improves their sports performance. Leucine is another BCAA that is important for protein synthesis, muscle growth, and repair. It also plays a role in regulating blood sugar levels and has been shown to have anti-inflammatory properties. Foods that are rich in lysine are meat, fish, eggs, dairy products, rice, legumes, bananas, apples, blueberries, olives.

3. Isoleucine

Isoleucine is an EEA that is necessary for the synthesis of proteins in the body. It is one of the three branched-chain amino acids (BCAAs) along with leucine and valine.

It is essential for muscle growth and repair, as it is involved in the synthesis of muscle proteins. It also plays a role in regulating blood sugar levels by stimulating the uptake of glucose into cells for energy production. Additionally, isoleucine is involved in the production of hemoglobin, the oxygen-carrying molecule in red blood cells.

This amino acid is rich in high-protein foods such as meat, poultry, fish, eggs, and dairy products. Also in almonds, oats, lentils, beans, cabbage, quinoa, hemp seeds, sunflowers and sesame, cranberries, apples, and kiwi.

4. Tryptophan

This amino acid is most needed nowadays because it improves the body’s adaptation to stress, improves mood, and mental and physical vitality. It is responsible for producing serotonin (hormone of happiness), that plays a role in mood regulation and sleep. It is also involved in the synthesis of proteins and the production of niacin (vitamin B3). relieving stress and depression.

An increased level of serotonin reduces the need for carbohydrates, so tryptophan is, among other things, excellent in fighting against obesity. Serotonin and melatonin (which are secreted during the night when the eyes are closed), belong to important neurotransmitters (transmitters of information between nerve cells) that play a key role in the normalization of sleep and mood,

Tryptophan can be found in foods like: beef, turkey, chicken, oats, eggs, milk, cheese, canned tuna, peanuts, walnuts, sesame seeds, cereals chocolate, pumpkin, banana,  pineapple, pepper…

5. Phenylalanine

It is a precursor to several important compounds, including tyrosine, dopamine, and adrenaline. It is also important for the production of proteins and for the synthesis of neurotransmitters in the brain. It is recommended for depression, neurological problems, and chronic pain.

For people who have a problem with appetite or struggle with anorexia, it can be very helpful because it strengthens their appetite. In combination with other supplements such as turmeric and frankincense, it can relieve rheumatic pain arthritis, and osteoarthritis.

Phenylalanine is found in high-protein foods such as beef, pork, lamb, venison, milk, cheese, yogurt, salmon, trout, tuna, lobster, legumes, almonds, pistachios, macadamia nuts, peanuts, quinoa, oats, berries, avocado, olives, grapes.

6. Threonine

Threonine is important for the synthesis of proteins and for the maintenance of healthy skin, hair, and nails. It is also involved in the production of neurotransmitters and the immune system.

It controls the accumulation of fat in the liver and it is necessary for the formation of glycine and serine, which are important for the formation of collagen, muscle tissue, and elastin. Some studies have shown that they can be alleviated by the use of threonine symptoms of multiple sclerosis and amyotrophic lateral sclerosis, especially in terms of spasticity muscle. Threonine deficiency may be associated with fatty liver and lipid disorders.

7. Valine

We can freely say that this amino acid can serve as an additional source of energy because it “keeps”glucose. It prevents the loss of muscle mass (e.g., in diabetes and in the elderly), helps in liver regeneration, and affects tissue growth and repair. Due to its ability to regenerate the liver, it is recommended for people who are being treated for diseases and addictions that have caused liver damage (drug addiction, alcoholism).

Some of the food sources that are high in valine include: beef, chicken, pork, turkey, salmon, and shrimp. Also in brown rice and whole wheat, beans, soybeans, lentils, peanuts, almonds, spinach, broccoli, sesame, blueberries.

8. Histidine

Histidine is important for the growth and repair of tissues, as well as for the production of red and white blood cells. It is also a precursor to histamine, a compound that plays a role in the immune system and helps to regulate stomach acid secretion. Histidine is found in high-protein foods such as meat, poultry, fish, dairy products, and whole grains.

9. Methionine

It belongs to the so-called thiamine amino acids, which have sulfur in their composition, which is why methionine is necessary for building cartilage. People who do not consume enough methionine are more likely to suffer from arthritis and have problems with wound healing

This essential amino acid participates in muscle development and helps the production of creatine. He is indispensable for an optimal level of energy in the cells.
The most important effect of methionine is to control homocysteine, an amino acid that damages blood vessels and is responsible for cardiovascular disease, dementia, and Alzheimer’s disease.

Methionine is important for the synthesis of proteins, as well as for the production of sulfur-containing compounds that are important for various bodily functions. It is also a precursor to other important compounds such as carnitine and taurine.

It can be found in high-protein foods such as meat, poultry, fish, eggs, and dairy products. Plants rich in methionine include sunflower, hemp seeds, brazil nuts, oats, wheat, algae, legumes, brown rice, onion, and cocoa.

Dangers and side effects

While essential amino acids are important for the proper functioning of the body, excessive consumption of certain amino acids or amino acid supplements can have negative side effects. Here are some of the potential dangers and side effects of essential amino acids:

Kidney damage: High levels of certain amino acids in the blood can cause damage to the kidneys, especially if you have pre-existing kidney disease. This is because the kidneys are responsible for filtering excess amino acids from the blood, and high levels can put a strain on them.

Gastrointestinal distress: Excessive intake of some amino acids, such as methionine, can cause stomach upset, diarrhea, and other gastrointestinal symptoms.

Headaches: High levels of the amino acid phenylalanine have been linked to headaches and migraines in some people.

Interference with nutrient absorption: Consuming too much of certain amino acids, such as leucine, can interfere with the absorption of other nutrients like tryptophan, which is important for the production of the neurotransmitter serotonin.

Allergic reactions: Some people may be allergic to certain amino acids, which can cause a range of symptoms from mild itching and hives to more severe anaphylaxis.

Hormonal imbalances: High levels of some amino acids, like methionine and cysteine, can interfere with the production of hormones like insulin and thyroid hormones.

It’s important to note that these side effects typically only occur with excessive consumption of amino acids or amino acid supplements, and are not a concern for most people who consume a balanced diet. If you are considering taking an amino acid supplement, it’s important to talk to your doctor or a registered dietitian to determine if it is necessary and safe for you to do so.

If you want to find out more about the dangers and side effects of every amino acid, please visit the National Library of Medicine


In conclusion, essential amino acids are a group of nine amino acids that the body cannot produce on its own, and therefore, must be obtained through the diet. These amino acids play a crucial role in many bodily functions, including protein synthesis, energy production, blood sugar regulation, hormone production, immune function, wound healing, and brain function.

Each essential amino acid has specific functions in the body, and a deficiency in any one of these amino acids can lead to a range of health problems, including muscle wasting, impaired immune function, and cognitive impairment.

Fortunately, essential amino acids can be obtained from a variety of dietary sources, including meat, poultry, fish, eggs, dairy products, and plant-based sources such as legumes, nuts, and seeds. Consuming a balanced diet that includes sufficient amounts of all of the essential amino acids is essential for maintaining optimal health and well-being.

Additionally, athletes and people who engage in high-intensity exercise may benefit from consuming amino acid supplements, particularly branched-chain amino acids, which can help to support muscle growth and recovery.