[katieHaylor (OP)]

Asutosh says:

What is the main function of non-essential amino acids inside our body?

What do you think?

[chiralSPO]

In the context of amino acids "essential" refers to the fact that you need the amino acids in your diet. Your body can make most of the amino acids (including glycine and arginine for example), but there are a few (like tryptophan and phenylalanine) that your body cannot make, and are therefore "essential" parts of your diet.

[evan_au]

In a sense, it is the "non-essential" amino acids that are most essential.

The "non-essential" amino acids are the ones where you would die rapidly without them. So your body must make all it needs.

The "essential" amino acids are ones where there is sufficient supply of them from multiple sources, or the effect of a temporary shortfall is so minor that you can get along without them for a while.

It is similar with "vitamins". Most mammals can synthesise all the vitamin C that they need. However, humans have a mutation that prevents them syntheisising vitamin C, so we must get it from our diet. Presumably, our ancestors lived in an environment where vitamin C was plentiful in the food supply, so the lack of vitamin C didn't become life-threatening until humans set out on long sea voyages, eating nothing but biscuits and fish.

Another odd case is cholesterol. This is demonized as something that will clog your arteries, strangle your heart and block your brain. But in fact it is an absolutely essential component of nerve cells - you would die rapidly without it. So your body synthesises all the cholesterol that it needs. It only becomes a problem when your diet contains more cholesterol than your body needs; it is so essential that your body lacks a good mechanism to dispose of the excess!