Written by Ben Bunting: BA(Hons), PGCert. Sport & Exercise Nutrition. L2 Strength & Conditioning Coach.
Amino acids are the building blocks of proteins, acting as one of the most vital things our body needs to function properly. 
Without them, we would run into major health problems extremely quickly, and it would become impossible to get the protein that the human body requires and are particularly important for the elderly population. 
However, despite being so important, not a lot of people know much about their own amino acids and why they are necessary.
In this article we shall cover:
- What are Amino Acids?
- Are all Amino Acids important?
- How many Amino Acids exist?
- What are essential Amino Acids?
- What are Non-Essential Amino Acids?
- What are the 20 Amino Acids good for?
- Essential Amino Acids
- Brached-Chain Amino Acids
- Non-Essential Amino Acids
- Identifying each Amino Acid
- Getting Amino Acids
What are Amino Acids?
At a basic level, amino acids are the thing we need to build muscle and maintain whatever muscle we already have. 
They are also extremely important for keeping your metabolism stable , can impact the hormones that your body produces, and are sometimes even good for dealing with stress or specific illnesses.
Not all amino acids are identical, and each type can have a different function or composition that changes how they are used. Most sources of protein contain amino acids, which your body breaks down into the acids themselves so that they can be used as new building blocks of proteins that your body needs. 
Are all amino acids important?
There are multiple types of amino acids, but that does not make all of them equally vital. Non-essential amino acids are still incredibly useful for specific purposes, but they are not quite as urgently needed. Still, the human body functions best when all amino acids are present and accounted for.
Certain diseases can make it harder for the human body to provide particular amino acids, such as cancer, making it difficult to manage your own arginine levels.
How Many Amino Acids Exist?
Out of roughly 50 amino acids found in nature, there are 20 amino acids in the human body.  Some are essential, others are not, but all of them have a function within your body that usually contributes towards your health and stability. A few - the essential ones - can't be produced by your body at all and need to be gathered from outside sources. 
What are essential amino acids?
Nine of the 20 amino acids in the human body are essential. This means that they are far more important for things like protein synthesis and general health, primarily because your body can't make them directly.  Each of these is a different amino acid with a different function, but they are generally gathered by eating protein that already contains amino acids. 
Essential amino acids are amino acids that make a big difference to your health if you stop eating protein. Your body can't make up proteins without them, and since you also can't produce them without eating protein to get the nine amino acids you need, it can quickly lead to nutrition problems and damage to the structure or health of your body. 
In fact, the consumption of essential or indispensable amino acids comes second in priority to energy requirements in the diet. 
What are non-essential amino acids?
Non-essential amino acids are amino acids that make a difference to your health but are not reliant on outside proteins in your diet. You do not need to get these from food since humans naturally produce them over time.
However, illness can upset the chemistry in your body, which may make it more important to get them from food or supplements until you are cured or healthy again. 
What are the 20 Amino Acids Good For?
Identifying the purpose of each protein source of amino acids can be quite useful. It is well-known that amino acids are found in protein, and also commonly known that specific amino acids may be used to produce certain protein types, but not many people know much more than that.
As the building blocks for important proteins, each of the 20 amino acids is very different, and no two are exactly alike. 
Here is a breakdown of what the 20 amino acids can provide, as well as an example of why they are so important in humans.
Essential Amino Acids
Essential amino acids are just that: essential amino acids that you need to keep in your diet if you want to stay healthy.
Branched-Chain Amino Acids
BCAAs are three types of an amino acid (valine, leucine, and isoleucine) that have a similar molecular structure with a small set of branching differences (a side chain).
Their molecular structure makes them important for muscle growth and energy in humans, so many people see them as a kind of supplement. In a way, they are, although the three are still part of natural muscle biology. 
These side-chain amino acids differ from one another, but the chains all lead back to the same starting point, so many people consider them the same amino acids unless they have to distinguish specific amino acid side chains from the other two. For example, valine stands out from the others due to the different chain structure of valine at a chemical level.
Lysine is a very common essential amino acid to see in information about protein-related biology. Lysine is important for general growth and preventing illnesses and is often found in non-wheat sources of proteins.
Communities that depend on wheat for their protein often end up with a Lysine deficiency. Therefore, fortification of foods can help reduce this deficiency. 
Threonine is a simpler essential amino acid that helps create the active site of enzymes, a catalyst for other important reactions.
It plays a role in fat mateabolism and the central nervous sytem.  This makes it extremely important in humans or any other living animal.
Phenylalanine is another essential amino acid that is very easy to explain. It is used to produce useful amines, which the body generally needs a reliable supply of. This amino acid often also helps with muscle regeneration and energy-building. 
Histidine is similar to Phenylalanine, but the two are still different amino acids that contribute to your health in different ways. It is an anti-inflammatory, antioxidant, helps with body weight management and cognitive function. 
Like the previous two amino acids, Tryptophan produces amines, which your body can rely on to help you stay healthy. It also helps with serotonin and regulates your appetite and sleep patterns. Tryptophan generally comes from animal and plant proteins but can't be produced by the body. 
Methionine is yet another essential amino acid with a simple explanation and produces a variety of useful substances that humans rely on. It is requred to make compounds within the body. 
Non-Essential Amino Acids
Amino acids come in many forms, all with different functional groups and protein sources. However, some are produced by the body directly. Here is an example of each non-essential amino acid.
Another amino acid, cysteine, provides the antioxidant glutathione to your body, as well as helping with the management of brain health, fertility, and even respiration. It is also responsible for preventing dry hair and making sure that your hair feels and looks 'right.'
Cysteine comes from high-protein foods, a loose group that can include things like eggs, cheese, and sunflower seeds. Cysteine can also be taken in supplement form.
Glycine is a chemical transmitter for the central nervous system. For example, it is often the first thing that your body will use to regulate your senses or locomotion skills. Not having enough Glycine makes it harder to move around properly or take in information consistently.
Meat, fish, and dairy have a high glycine content, making it one of the easier amino acids to get. You can also get it as a supplement, with the same properties as the natural amino acid.
Glutamate it is a neurotransmitter that helps our brains manage nervous system signals, and can also be involved in learning and memory functions. It is also used for the synthesis of various useful molecules within the body.
A common amino acid, Glutamine, aids the stomach and digestive tract, as well as producing energy. This makes it important for the safe digestion of food, as well as the metabolization of alcohol, to stop overloading the liver. As a non-essential amino acid, it is one of the amino acids that your body will produce on its own.
Asparagine, named after the asparagus that it was first discovered in, is used to break down toxic ammonia inside your body's cells as well as produce aspartic acid. This is vital for survival at any age, especially in children who are still developing.
Aspartate is an energy-focused amino acid and has ties to the tricarboxylic acid cycle that our body uses to produce energy on a larger scale. This means that it may also stave off fatigue, and many athletes see it as a natural supplement. There are some studies that demonstrate the effectivness of D-Aspartic Acid increasing testosterone and fertility.
Tyrosine is essential for developing multiple useful neurotransmitters, as well as handling melanin (the pigment that dictates your hair and skin color). It can also improve your mood and regulate it to prevent sudden changes or swings.
Tyrosine comes from dairy products and is naturally created through another amino acid - Phenylalanine. The properties are the same no matter which one you get your Tyrosine from. A functional group of Tyrosine is not called Tyrosine, but Tyrosyl, although this only really matters when looking at ingredient lists of supplements or the specific chemical code of Tyrosine itself.
Arginine is used to open veins and improve blood flow, mainly through the creation of nitric oxide. It can also boost the immune system and remove excess ammonia from your body. This makes it necessary for almost anybody, especially athletes who need better blood flow.
The properties of Arginine make it one of the most well-known amino acids, and it is common to see it in a group of the essential supplements for building up an exercise structure. Using Arginine for its blood flow properties is generally safe, and it can become one of the most useful natural amino acids to add to your diet or meal structure.
Alanine is mainly used to support your liver functions and produce glucose, as well as aid in the chemistry behind the metabolization of alcohol. It also acts as another energy source for your central nervous system and can strengthen your immune system.
Proline is used to promote tissue regeneration (for example, letting skin heal) and can also be used to produce collagen, which is part of the development for most of your biology: bones, skin, muscles, and the prevention of sagging or baggy skin.
Serine is used to make phosphatidylserine, which is useful for keeping your brain cells healthy. It can also be used to transmit signals from the brain itself, which makes it a very popular way to try and treat various life-altering brain conditions such as schizophrenia.
Identifying Each Amino Acid
There are 20 amino acids, including nine essential amino acids, that make up protein in your body through protein synthesis.
Between histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and glutamine, it can be almost impossible to keep track reliably when you first hear about all of the different amino acids your body needs to create proteins.
However, you do not usually need a way of telling the difference between histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and so on. Even when some amino acids overlap, you only really need to know the chemical content, group, or chain structure if you are trying to handle something yourself.
Most medical professionals are aware of how essential amino acids make up proteins in your body and will be able to handle the chemistry or chemical content details themselves. Most of the time, the name of an amino acid acts more like a code for what it does: most of them are different enough to be clearly distinct.
Getting Amino Acids
It does not take much chemistry skill to know that amino acids are generally found in protein, or others such as D-Aspartic Acid are popular in supplements. Sometimes these are specifically plant proteins, sometimes animal proteins, and many are found in most proteins either way. Most of the time, the source varies based on the amino acid. Glutamine (and glutamic acid) is found in plant protein most of the time, and asparagine/aspartic acid can be found in asparagus (as the name suggests).
Remember not to confuse nucleic acids, amino acids, and other acid types. Proteins and amino acids like glutamic acid are used to form proteins (through protein synthesis) and provide nutrition or other chemical benefits, whereas nucleic acids do not share the same properties. Not all acids are amino acids, and their properties are not shared just because they are considered acids.
A balanced and mixed diet should give you every essential amino acid in some form, with the other amino acids being produced by your body. While only nine of them need to be in your diet, you may want to introduce some of the non-essential amino acids if you are sick or want to be sure that you are getting enough.
In terms of a vegan diet, it may just take some extra care to avoid a deficiency - this may mean ensuring that you eat a wide range of plant based proteins and not just focusing on one or two. 
It is hard to have too many amino acids, and you can't really suffer an amino acid overdose, so do not be afraid to put more amino acid-full proteins in your normal diet or nutrition plan. A balanced structure may help you in the long run when you get a disease or illness that alters how you can naturally produce proteins, providing all of the necessary amino acid proteins to make life easier while you recover.