Amino acids are hugely important organic compounds; they’re necessary for biological life even in its most basic form. In us as in other animals, amino acids are used to form proteins, which are some of the major building blocks of life.

In our bodies, amino acids are used to break down food, to grow and repair bodily tissues, and to perform other major bodily functions. In some cases, amino acids can also be used as energy sources.

Ever wondered how your body produces new muscle tissue after working out for several weeks or months? As you work out, your muscle tissues tear and your body fills in the gaps in those muscle tissues with new proteins derived from amino acids. 

In this way, your muscles are directly affected by how many amino acids you consume (or that your body produces).

However, amino acids are separated into three major groups: essential, nonessential, and conditional. 

Of these, essential and nonessential are the most important and are the most misunderstood. Let’s take a closer look at essential versus nonessential amino acids so you understand their differences and their key uses in your body.

Essential Amino Acids

“Essential” and “nonessential” don’t mean the exact same things for amino acids as they do elsewhere.

In biology, an essential amino acid cannot be made by your body. Instead, humans get essential amino acids from their diets and from supplements. Essential amino acids include 9 out of all 20 amino acids necessary for biological functions. They are:

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

Interestingly, eight out of these essential amino acids are necessary for adults. Adults don’t need the ninth essential amino acid, histidine, as it is only necessary for the growth of infants’ various bodily tissues and muscles. 

Essential amino acids are used for a wide range of important functions. For example, essential amino acids are often used to build muscle and to build other key bodily tissues, including organ cells, skin cells through collagen formation.

Typically, an adult body needs about 0.5 g of protein per pound of lean body weight each and every day. The bigger you are, the more amino acids you need to maintain that bodily mass. This is why many workout and fitness supplements include essential amino acids.

Remember, your body can’t produce essential amino acids by itself, so you have to get enough of them from other sources.

Nonessential Amino Acids

Even though nonessential amino acids don’t sound important, they certainly are. In fact, they are just as classically essential as essential amino acids. The big difference? Your body can create or synthesize nonessential amino acids, at least to some extent. 

Nonessential amino acids include all the 11 remaining amino acids, such as:

  • Arginine
  • Glutamine
  • Cysteine
  • Tyrosine
  • Glycine
  • Proline
  • Ornithine
  • Alanine
  • Serine
  • Asparagine
  • Aspartate

Just like their essential counterparts, nonessential amino acids fill several key roles in your body. For example, many nonessential amino acids are used to support the growth and repair of new tissues, as well as to help your body synthesize new red blood cells. Without nonessential amino acids, your body wouldn’t be able to produce new blood.

Additionally, nonessential amino acids are absolutely vital for the proper functioning of your immune system, so they help to protect you against diseases. Your body further uses nonessential amino acids for hormone synthesis.

The big difference between essential and nonessential amino acids is this: given enough protein, your body can usually create all 11 nonessential amino acids by itself. While nonessential amino acids in your diet or supplements can be helpful, they are not strictly necessary.

Because of this, fitness protein supplements usually target essential amino acids instead of nonessential acids.

A Third Category: “Conditional” Amino Acids

Technically, there’s a third category of amino acids called conditional amino acids. These have a special function in the body and are categorized separately because they are usually not essential, except in times when your body is placed under extreme stress or becomes ill.

In a nutshell, if your body is being taxed by other tasks or conditions, it won’t be able to synthesize certain amino acids that are normally part of the nonessential amino acid group. 

These acids include:

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

In cases where your body can’t produce these amino acids, you’ll need to get these from ancillary sources, like your diet or supplements. Because conditional amino acids only become such during times of illness for most people, certain amino acids are sometimes included with medicines or other treatments, especially when it comes to repairing tissue damage (such as after an intense injury). 

Which Amino Acids Are Most Important?

All of them!

It’s not a good idea to think of amino acids as more or less important from one another. Your body requires all 20 key amino acids in order to synthesize all of the bodily tissues that make up your body mass, as well as to produce hormones and other vital chemicals.

All the amino acids are necessary for one reason or another, and many work in conjunction with one another. If you were to remove several amino acids from the mix, the others might not function properly.

Therefore, you should make sure to include plenty of protein in your diet so your body can synthesize nonessential amino acids as well as take a regular supplement that includes the essential amino acids necessary for holistic bodily health.

Summary

Ultimately, essential and nonessential amino acids are both critical for bodily health and to make sure your body can grow new muscle tissue and rebuild tissue after an intense workout. Be sure to target supplements with all the major essential amino acids if you want to maximize your muscle growth and reach your peak physical potential.

Sources

Nonessential Amino Acid | Science Direct

Amino Acids | Medline Plus 

Biochemistry, Essential Amino Acids – StatPearls | NCBI