Our body requires 20 amino acids (the building blocks of protein), 9 of which it can’t synthesize (thus called: “essential”) and absolutely must get from food. Normally, we get these amino acids from protein in our diet, and we can also supplement them by taking amino acid supplements if we wish.

Specifically, we require (per kg of bodyweight) a daily average of:

1. Histidine: 10 mg
2. Isoleucine: 20 mg
3. Leucine: 39 mg
4. Lysine: 30 mg
5. Methionine: 10.4 mg
6. Phenylalanine*: 25 mg
7. Threonine: 15 mg
8. Tryptophan: 4 mg
9. Valine: 26 mg

*combined with the non-essential amino acid tyrosine

Source: Protein and Amino Acid Requirements In Human Nutrition: WHO Technical Report

Why this matters

A lot of attention is given to protein, and making sure we get enough of it, especially as we get older, because the risk of sarcopenia (muscle mass loss) increases with age:

Protein vs Sarcopenia

However, not every protein comes with a complete set of essential amino acids, and/or have only trace amounts of of some amino acids, meaning that a dietary deficiency can arrive if one’s diet is too restrictive.

And, if we become deficient in even just one amino acid, then bad things start to happen quite soon. We only have so much space, so we’re going to oversimplify here, but:

1. Histidine: is needed to produce histamine (vital for immune responses, amongst other things), and is also important for maintaining the myelin sheaths on nerve cells.
2. Isoleucine: is very involved in muscle metabolism and makes up the bulk of muscle tissue.
3. Leucine: is critical for muscle synthesis and repair, as well as wound healing in general, and blood sugar regulation.
4. Lysine: is also critical in muscle synthesis, as well as calcium absorption and hormone production, as well as making collagen.
5. Methionine: is very important for energy metabolism, zinc absorption, and detoxification.
6. Phenylalanine: is a necessary building block of a lot of neurotransmitters, as well as being a building block of some amino acids not listed here (i.e., the ones your body synthesizes, but can’t without phenylalanine).
7. Threonine: is mostly about collagen and elastin production, and is also very important for your joints, as well as fat metabolism.
8. Tryptophan: is the body’s primary precursor to serotonin, so good luck making the latter without the former.
9. Valine: is mostly about muscle growth and regeneration.

So there you see, the ill effects of deficiency can range from “muscle atrophy” to “brain stops working” and “bones fall apart” and more. In short, any essential amino acid deficiency not remedied will ultimately result in death; we literally become non-viable as organisms without these 9 things.

What to do about it (the “life hack” part)

Firstly, if you eat a lot of animal products, those are “complete” proteins, meaning that they contain all 9 essential amino acids in sensible quantities. The reason that all animal products have these, is because they are just as essential for the other animals as they are for us, so they, just like us, must consume (and thus contain) them.

However, a lot of animal products come with other health risks:

Do We Need Animal Products To Be Healthy? ← this covers which animal products are definitely very health-risky, and which are probably fine according to current best science

…so many people may prefer to get more (or possibly all) dietary protein from plants.

However, plants, unlike us, do not need to consume all 9 essential amino acids, and this may or may not contain them all.

Soy is famously a “complete” protein insofar as it has all the amino acids we need.

But what if you’re allergic to soy?

Good news! Peas are also a “complete” protein and will do the job just fine. They’re also usually cheaper.

Final note

An oft-forgotten thing is that some other amino acids are “conditionally essential”, meaning that while we can technically synthesize them, sometimes we can’t synthesize enough and must get them from our diet.

The conditions that trigger this “conditionally essential” status are usually such things as fighting a serious illness, recovering from a serious injury, or pregnancy—basically, things where your body has to work at 110% efficiency if it wants to get through it in one piece, and that extra 10% has to come from somewhere outside the body.

Examples of commonly conditionally essential amino acids are arginine and glycine.

Arginine is critical for a lot of cell-signalling processes as well as mitochondrial function, as well as being a precursor to other amino acids, including creatine.

As for glycine?

Check out: The Sweet Truth About Glycine

Enjoy!