Amino Acids Explained: All 20, Protein Powder and What Actually Matters

The word essential does not mean more important. It means the body cannot synthesise enough of that amino acid, so it must arrive through the diet. The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

The remaining standard amino acids are normally produced by the body. Arginine, cysteine, glutamine, glycine, proline and tyrosine are often described as conditionally essential because demand can exceed production during growth, serious illness, injury or other physiological stress.

A supplement label that shouts about a non-essential amino acid is not automatically dishonest—glutamine and glycine have real biological roles—but its presence does not necessarily improve an already adequate protein powder.

The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Your body cannot produce enough of them, so they must come from food or supplements containing dietary protein.

Each performs a different role, but none works in isolation. If one essential amino acid is genuinely limiting, the body cannot use all the others efficiently for new protein synthesis. The table below explains what each one does, where it comes from and why it matters when comparing protein powders.

Non-essential amino acids still perform essential biological work. The label describes where they come from, not whether the body needs them. In healthy adults, eating sufficient protein supplies their raw materials while the body synthesises additional amounts as required.

BCAAs are only leucine, isoleucine and valine. EAAs include those three plus histidine, lysine, methionine, phenylalanine, threonine and tryptophan. A complete intact protein supplies all nine essential amino acids in useful amounts.

BCAAs can activate parts of the muscle-protein-synthesis signalling pathway, but the response is smaller than with a complete protein containing all essential amino acids. That makes a BCAA drink a poor substitute for whey, soy or a well-designed plant blend.

Free-form EAA products can be useful when a full shake or meal is impractical, but they are usually more expensive per meaningful dose and provide less satiety. For ordinary gym use, intact protein remains our default recommendation.

A manufacturer earns more credit for publishing a usable amino-acid table than for printing an enormous BCAA number on the front. These products illustrate five different approaches currently represented in the ProteinDeals catalogue.

The ranking is about transparency and protein design, not a claim that one fixed product is permanently cheapest. Use the live comparison beneath it for current price order.

Product	Protein design	Amino-acid strength	ProteinDeals verdict
Peak Supps Whey Protein Isolate 90 Pros +Whey concentrate supplies a complete essential-amino-acid profile +Subscription drops the pack from £149.99 to £134.99, saving £15.00 (10%) Cons −Whey concentrate may not suit lactose-sensitive users −Lowest price requires a recurring subscription	Whey isolate	Publishes a full profile including each EAA	Best transparency example and naturally leucine-rich.
Huel Complete Protein	Pea, faba and brown rice	Publishes total EAAs and BCAAs per serving	Strong vegan blend, although individual EAA values would be even better.
MyProtein Soy Protein Isolate	Soy isolate	Complete single-source plant protein	Our value-first vegan benchmark when its live unit price is competitive.
Peak Supps Pea Protein Isolate 80 Pros +Whey concentrate supplies a complete essential-amino-acid profile +Subscription drops the pack from £159.99 to £143.99, saving £16.00 (10%) Cons −Whey concentrate may not suit lactose-sensitive users −Lowest price requires a recurring subscription	Pea isolate	Useful lysine and leucine; relatively lower methionine	Good budget base when the rest of the diet is varied.
Optimum Nutrition Gold Standard Whey Pros +Whey concentrate supplies a complete essential-amino-acid profile +Subscription drops the pack from £170.00 to £161.50, saving £8.50 (5%) Cons −6.2% above the £3.53/100g average across 62 comparable /compare listings −Whey concentrate may not suit lactose-sensitive users	Whey isolate/concentrate blend	Complete protein with a declared total BCAA figure	Reliable, but remember total BCAAs are not a leucine measurement.