What Are Essential Amino Acids?

Amino acids are the molecules that make up proteins and are a crucial part of any well-balanced diet. There are several different types of amino acids, including essential, non-essential, and conditional. But what do these terms mean, and why are they important?

This article explains in detail, focusing on essential amino acids and how they influence our health.

What Are Essential Amino Acids?

Biologists often refer to proteins as the building blocks of life. They enable our cells and tissues to grow and repair themselves continuously. They also make up many of the chemicals that keep our bodies running smoothly.

Enzymes that digest our food, hormones that allow our cells to communicate, and neurotransmitters that control our mood and behavior; All of these vital molecules are proteins.


There are also many others that influence immunity, sleep, appetite, and more.

There are approximately 100,000 unique proteins in the human body, and to create them, we need amino acids. They are nitrogen-containing molecules that combine to form larger protein chains, all with distinct functions.

There are hundreds of different amino acids in nature, but most plant and animal proteins only require around 20. The body is capable of synthesizing many of these amino acids by itself. However, it has to get the remainder from food, and these are the essential amino acids.

Essential vs. Non-Essential Amino Acids

The difference between essential and non-essential amino acids is that the body can only make non-essential amino acids. It must extract essential amino acids from food.

The body can only make non-essential amino acids. It must extract essential amino acids from food.

There is also a third group of amino acids, known as conditional amino acids. These are amino acids that are non-essential under normal circumstances. However, during times of illness or stress, we may be unable to synthesize them and must get them from food instead. 

How Many Amino Acids Are Essential?

Of the 20 amino acids we require to stay healthy, nine are essential. Below, we list the different essential, non-essential, and conditional essential amino acids:


  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Valine


  • Alanine
  • Arginine
  • Asparagine
  • Aspartic acid
  • Cysteine
  • Glutamine acid
  • Glutamine
  • Glycine
  • Proline
  • Serine
  • Tyrosine


  • Arginine
  • Cysteine
  • Glutamine
  • Glycine
  • Ornithine
  • Proline
  • Serine
  • Tyrosine

Benefits of Essential Amino Acids

Amino acids are essential to life, and not consuming enough can cause serious health problems. Fortunately, most people get plenty of these nutrients from their diets. Therefore, in economically developed countries, protein deficiency is rare.

The recommended daily protein intake for most adults is 0.8 grams for every kilogram of body weight. So, an adult male weighing 80 kg (176 lb) would need to consume approximately 64 grams of protein each day. Meanwhile, an adult female weighing 65 kg (143 lb) would need to consume around 52 grams.

However, some people need more protein in their diets. They include pregnant or breastfeeding women and those with chronic health conditions.

People with demanding fitness regimes also need more protein than average. For example, if someone is continually damaging their muscles through exercise, they will need extra protein to repair them.

Therefore, some people may struggle to get all the protein they need from food. This is where amino acid supplements come in. They ensure that individuals receive the amino acids they need to keep functioning optimally, even when under stress.

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There is even some evidence that amino acid supplements might improve longevity. In one 2010 study, researchers fed an amino acid-rich diet to mice. They found that the treated animals lived an average of 869 days compared to controls, who lived an average of 774 days.

The study’s authors suggest that the health benefits of essential amino acid supplements are numerous. They include countering the following age-related disorders:

  • Loss of muscle mass
  • Insulin resistance
  • Type 2 diabetes
  • Cardiovascular dysfunction

Of course, further research is needed to confirm these results and explore how they apply to humans. We hope to see more evidence emerging soon.

Essential Amino Acid Supplement Options

Most amino acid supplements come in powder or capsule form.

Some contain a full range of all nine essential amino acids. However, many only contain the branched-chain amino acids (BCAAs), isoleucine, leucine, and valine.

It is necessary to choose carefully as some amino acids could potentially be harmful in the wrong ratios. For example, the body uses the essential amino acid methionine to make the non-essential amino acid cysteine. However, to do so, it must create an intermediary molecule called homocysteine, which is toxic.


Therefore, supplements containing methionine should also contain cysteine to reduce the rate of this conversion. Furthermore, the non-essential amino acids arginine and glutamine could be harmful if supplemented long-term.

Moreover, the supplements market is not well-regulated, meaning that many brands produce low-quality goods. Some experts argue that it is better to meet our amino acid nutrition needs using food because of these issues.

Essential Amino Acid Food Sources

Some of the best food sources of essential amino acids are animal products, including meat, poultry, seafood, and eggs. These are complete proteins, meaning that they contain all nine essential amino acids.

Plant-based proteins generally lack one or two essential amino acids, making them “incomplete.” Therefore, vegetarians and vegans must ensure that they eat a variety of high-protein foods each day. One exception to the rule is soy, which is considered a complete protein.

It is best to eat a selection of different foods with essential amino acids daily.

Plant proteins also tend to be harder to digest than those from animal products. However, diets based on animal-derived protein can also be detrimental to one’s health. These foods are often high in saturated fat and cholesterol, which negatively impact heart health.

Therefore, it is best to eat a selection of different foods with essential amino acids daily. Some good examples include:

  • Lean meat
  • Poultry
  • Fish
  • Shellfish
  • Eggs
  • Pulses (peas, beans, lentils, etc.)
  • Soy products (tofu, tempeh, etc.)
  • Nuts or nut butter
  • Seeds

The Bottom Line on Essential Amino Acids

The benefits of essential amino acids stretch far beyond increasing muscle size and strength. They are among the most fundamental nutrients for our health and wellbeing. Therefore, it is vital to eat enough protein every day.

While most people can get enough amino acids from their diets, those who can’t may consider supplementation. However, it is crucial to use supplements with caution to ensure that they are not doing more harm than good.

Anyone concerned about their amino acid intake should consider consulting a dietician for further advice. To learn more about choosing a safe and effective amino acid supplement, see our article on the best amino acid products.

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