Amino Acids Demystified: Essential vs. Nonessential – Know the Difference

The essence of life oozes from the building blocks of protein: amino acids. Without these organic compounds, our bodies would not grow or repair damaged tissues. But did you know that not all amino acids are created equal? In fact, there are two main categories: Essential vs. nonessential amino acids. 

The difference between essential and nonessential amino acids is that essential amino acids are those that our bodies cannot produce. You can only get them from dietary sources like animal protein like meat, dairy, or eggs, and plant-based products like legumes. There are 21 amino acids, and only nine are essential.

Now, let’s go into the details. This post will explain the role of amino acids in biological processes and highlight the important differences between essential and nonessential amino acids.

Understanding Amino Acids

We know that carbon, hydrogen, and oxygen are the three most common elements in living organisms. However, amino acids differ from this trio as they also contain nitrogen (N), with some having sulfur (S). So, what are amino acids, and why do you need them?

We like to define amino acids as organic compounds consisting of a carboxyl-terminal (-COOH) group, a side chain (R-group,) and an amino-terminal (-NH2) group. The R-group is the key to differentiating one amino acid from another. 

There are twenty unique combinations of R-groups, thus leading to twenty distinct amino acids. A recent discovery found a twenty-first amino acid, selenocysteine (Sec), which has an important role in the body. Find out more in this post: “How many amino acids are there: 20 or 21?

Protein synthesis takes place in ribosomes, which translate instructions from our genes into protein sequences. For the synthesis to occur, this process requires 20 different amino acids. The human body can only synthesize eleven out of the twenty amino acids.

Essential Amino Acids

Nine of the 21 amino acids fall in the essential category, as your body cannot produce them independently. They’re absolutely necessary for the proper functioning of the body, so you need to incorporate them into your diet. 

Here’s a detailed list of the nine essential amino acids, highlighting their sources and importance in the body:

  1. Leucine: This branched-chain amino acid (BCAA) is vital for protein synthesis, muscle growth, and repair. You’ll find it in fish, chicken, beef, beans, nuts, and dairy products.
  2. Isoleucine: Also a BCAA, this amino acid is crucial for energy production and immune function. It’s in foods like eggs, soy, poultry, fish, and lentils. 
  3. Valine: This one is essential for proper brain and nervous system function. It’s found in dairy products, poultry, fish, peanuts, and sesame seeds.
  4. Methionine: This amino acid is key in metabolism and detoxification processes. You’ll find it in animal proteins like meats, fish, dairy, and seeds and nuts. 
  5. Phenylalanine: This amino acid is important for producing neurotransmitters, hormones, and proteins. It’s found in dairy products, meat, fish, beans, and nuts. 
  6. Threonine: This amino acid is essential for maintaining muscle and connective tissue health. You’ll find it in dairy products, eggs, poultry, meats, and beans.
  7. Tryptophan: This amino acid is the forerunner to serotonin, so it plays a role in mood regulation. To get it, eat turkey, chicken, soy products, nuts and seeds.
  8. Histidine: This amino acid is important for growth and tissue repair. It’s found in foods like meat, fish, poultry, eggs, dairy products, and beans.
  9. Lysine: Last but not least, this essential amino acid is crucial for bone health and energy production. It’s in foods like meats, dairy products, beans, and nuts.

Here’s more on the 9 essential amino acids foods for proper dietary planning.

Nonessential Amino Acids

Our body synthesizes most of the amino acids it later uses to build proteins. We have the enzymes in our cells that catalyze the production of amino acids from other molecules. 

Such an amino acid, which we can produce endogenously without relying on our dietary intake, qualifies as a nonessential amino acid.

So, how many nonessential amino acids are there? While the list may vary slightly depending on the source, there are generally considered to be 11 nonessential amino acids in humans.

The twelfth nonessential amino acid, [selenocysteine], is only in particular proteins and does not yet feature in the standard list of amino acids. Your body needs it so the enzymes involved in redox reactions can function properly.

We won’t list all the nonessential amino acids here, but some of the most common ones include: 

  1. Alanine: This amino acid is key in metabolizing glucose for energy production. It’s also crucial for maintaining proper nervous system function.
  2. Asparagine: Another important amino acid involved in protein synthesis, it also acts as a precursor to other molecules like purines and pyrimidines.
  3. Glutamine: You need this amino acid to improve your gut health and immunity. It’s also important for removing excess ammonia from the body.
  4. Glycine: This nonessential amino acid helps to synthesize other substances like creatine and glutathione. It’s also necessary for maintaining healthy skin, joints, and muscles. 

As you can see, even though these amino acids are not considered “essential” because our body can produce them, they still play important roles in maintaining our overall health and well-being.

Sometimes, the body may be unable to produce some nonessential oils. For example, you may have insufficient levels of glutamine after suffering from a severe illness or injury. In such cases, increasing your dietary intake of glutamine-rich foods or glutamine supplements may be beneficial. 

Yes, you can ingest nonessential amino acids through food or supplements, just like with essential amino acids. It’s just that you can’t do without the essential amino acids.

Essential vs. Nonessential Amino Acids

As mentioned earlier, our daily diet requires essential amino acids as we lack the necessary enzymes and microbial pathways for their synthesis. In contrast, our bodies can manufacture nonessential amino acids independently via biochemical pathways that break down stored proteins. 

But it’s not just the source of these amino acids that distinguishes them; there are also differences in their chemical structures and functions.

  • Essential Amino Acids

These are typically smaller molecules with simple structures, allowing them to be easily absorbed and utilized by the body. They are also involved in crucial metabolic processes, such as building proteins and enzymes, synthesizing hormones, and maintaining proper immune function.

  • Nonessential Amino Acids

These tend to be larger and more complex molecules with additional functional groups. They play important roles in the body’s energy production, nerve transmission, and detoxification processes.

Final Thoughts on Essential and Nonessential Amino Acids

While essential and nonessential amino acids may have distinct roles, they also work together in a delicate balance to support overall health. So, whether you’re getting your amino acids through food or supplements, it’s essential to maintain a well-rounded and balanced diet.

You may need to consume nonessential amino acids even though your body can produce them, as certain health conditions or lifestyle factors may increase demand. 

Additionally, the proportion of essential to nonessential amino acids in a food source can vary. So, you need to eat a wide variety of foods, and having different meals every day also makes eating enjoyable.  

We recommend you avoid changing your diet and supplement doses drastically without ample research and consultation with a professional. Always take the time to ask your doctor or nutritionist before making drastic changes and your body will thank you in the long run! 

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