What are EAAs?
Essential amino acids are the nine the body cannot synthesise: leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, and histidine. Any complete protein source, such as whey or meat, contains all nine. Free-form EAA supplements provide them in a rapidly absorbed form.
How it works
Muscle protein synthesis requires the full set of essential amino acids as building substrate. Leucine acts as the trigger, but the other eight are needed to actually build tissue. This is why EAAs are more complete than BCAAs, which provide only three of the nine.
What the research says
- EAAs stimulate muscle protein synthesis more completely than BCAAs alone (Jackman et al., 2017)
- Around 10g of EAAs can match the synthesis response of a standard whey serving
- The benefit is greatest when training fasted or when daily protein is low
- They offer no added benefit over whole-food protein when intake is already sufficient
Effective dose
10–15g around training, containing roughly 2–3g of leucine. For most people eating enough protein, a normal meal or a whey shake does the same job at lower cost.
What to check on the label
A genuine EAA product lists all nine amino acids, not just the three BCAAs. Check the leucine content and be wary of products that are mostly BCAAs with token amounts of the remaining six.
Safety
Well tolerated. Free-form EAAs are essentially supplemental protein, and no adverse effects are established at typical doses in healthy adults.