EAA
The nine amino acids the body cannot make, taken mostly around training.
- Muscle and training
- Soreness and recovery
- Topping up protein
- Muscle in later life
- Walking and moving about
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
On this page
What is EAA?
EAA stands for essential amino acids: the nine that the body cannot make for itself, or cannot make quickly enough, so they have to come in with food. They are leucine, isoleucine and valine, the three branched-chain ones that are also sold on their own as BCAA, along with tryptophan, phenylalanine, histidine, methionine, threonine and lysine. A tub holds the whole set in free form, usually a flavoured powder with extra leucine, so a scoop supplies only the part of a protein that the body builds with. It is popular for that reason: it adds amino acids to a meal or a session without the volume or the fullness of a protein shake.
Why do people take EAA?
Muscle and training
The thinking. This is what most tubs are bought for. Muscle is built out of amino acids, nine of which have to arrive from outside, so the idea is that having the whole set to hand around a session leaves the body nothing to wait for. Leucine is the one that carries the start signal, which is why blends are usually built around it.
What research has found. One four-week trial in young men compared essential amino acids alone, resistance training alone, and the two together. Lean mass rose only where people both trained and took them; the strength measures that moved were in the training groups, and inflammation and muscle-signalling markers fell in every group that did either. Few studies have measured this yet, so there is little to go on either way.
Soreness and recovery
The thinking. Hard or unfamiliar training leaves muscles sore and stiff for a day or two and pushes markers of muscle damage into the blood. Amino drinks are taken around those sessions in the hope of shortening that, on the thinking that repair draws on the same raw material as building, and that a free-form powder reaches the blood quickly.
What research has found. One trial gave twenty recreationally active men a leucine-enriched essential amino acid blend three times a day for four days after a hard lower-body session, alongside a controlled diet. Muscle damage was moderately reduced against a dummy drink, while the rate at which muscle protein was actually built over those four days was no different. Very little research has measured this so far, either way.
Topping up protein
The thinking. Some people reach for essential amino acids instead of a protein shake rather than as well as one: older adults with small appetites, people eating less to lose weight, anyone whose meals are light on protein. The idea is that a few grams sit alongside a meal without filling you up, and that the body has to unpick a whole protein to reach them anyway.
What research has found. Three small trials measured protein building in the hours after a drink, in trained volunteers and in older adults, some healthy and some living with a serious illness. Each found more laid down after free essential amino acids than after a matched mixture built to the make-up of a complete protein. Research here is still young: a few studies so far, mostly pointing the same way.
Muscle in later life
The thinking. Muscle and strength slip away from middle age onwards, and appetite often goes with them, so people can end up eating less protein at the point they would need more. Essential amino acids are taken alongside meals for that reason, usually with some resistance exercise, in the hope of holding on to what is there.
What research has found. A six-month trial in healthy, independent older adults found walking speed and fitness rose with the exercise whatever people took, muscle strength rose only where supplement and exercise went together, and lean mass did not shift in anyone. A second trial reported only the result for a blend that also held compounds from tea, so what the amino acids did alone is not stated. This has barely been studied yet, so there is not much to go on.
Walking and moving about
The thinking. Getting out of a chair, crossing a road before the lights change, carrying shopping upstairs: these are the things people notice slipping before any number on a scale does. Essential amino acids are taken with meals in the hope of keeping that everyday capacity, and it is what several of the older-adult trials measured.
What research has found. A review of trials in people over sixty found essential amino acids the one supplement it looked at with a consistent effect on physical performance, in three of its four trials, though it judged that evidence low in quality. A twelve-week trial in older adults with low physical functioning found the group taking a blend walked further in six minutes than the group taking whey protein. Only a few studies have measured this so far, though they mostly agree.
What does EAA do in the body?
Protein in food is a long chain of amino acids. Digestion snips it apart and the loose pieces go into the blood, where the body rebuilds them into whatever it needs that day. Nine of them it cannot make for itself, or cannot make quickly enough, so those nine have to keep arriving. A free-form supplement skips the snipping: the amino acids are already loose, so they turn up in the blood quickly.
Inside muscle they do two things at once. They are the bricks, built into new muscle protein, and they are the instruction, leucine most of all, that tells a muscle cell to start building. That signal rises further with the full nine than with the branched-chain three on their own. Amino acids are also fuel, though, and when energy is short a greater share of what arrives is burned or spent on the body’s other protein-making, rather than on muscle, which is one reason the same amount behaves differently in different circumstances.
What do people say about taking EAA?
These are anecdotes people have shared, not evidence.
What people like
- Five threads from strength, triathlon and cycling boards; posters move freely between branched-chain and full essential blends, and only a few name all nine.
- Easier recovery and less soreness in the days after a hard session is the commonest thing people say they noticed.
- Several take a small serving while training fasted, or between a morning coffee and the first meal, saying it takes the edge off hunger.
- A couple describe more energy: one through a long stretch of fatigue, and a partner who found the afternoons easier.
Common complaints
- The commonest objection by far is that anyone already eating enough protein is paying for what their meals deliver anyway.
- Nearly as common: people tried it, could point to no difference, and several stopped once their everyday eating had settled down.
- A few worry it breaks a fast or interrupts autophagy, since the amino acid that carries the building signal is the point.
- Only one poster described a side effect: a spell of irritability that made them stop, though they later went back to it.
How people take it
- Powder stirred into water or a sports drink is the usual form, and most take it around training, before or straight after.
- Amounts are rarely named. Where they are, they run from one small serving to about ten grams after a heavy session.
- Timing splits three ways: around a session, before bed, and in the fasted stretch between waking and the first meal.
- Most who take it also take protein powder, and several mix it with other single amino acids rather than using it alone.
- The sceptics’ reply runs through every thread: sort daily protein and whole food first, with the tub kept as the last thing added.
Read from these public discussions:
- What role (if any) does Amino supplements play in your nutrition? (StrongFirst, 2024)
- Fasting, fasted training, and bcaa (StrongFirst, 2020)
- Amino acid supplement recommendations (Slowtwitch, 2022)
- Amino Acid Supplements (Slowtwitch, 2011)
- Amino acids BCAA / EAA - YES or NO (TrainerRoad, 2023)
What forms of EAA are there?
| Form | What’s different | Per serving, on products we list |
|---|---|---|
| EAA (total) | All nine essential amino acids weighed together as free amino acids; many blends carry extra leucine. | 200 mg |
What else is worth knowing about EAA?
- Labels give the total essential amino acids per serving, which is often more than one scoop. The amounts trials used vary a lot: 3 g a day in one study of older adults, 4 g three times a day after hard training, 9 g a day around surgery, 15 g a day for six months, and 20 g twice daily in one short study.
- Most blends are built around leucine and say so on the front; one trial’s mixture was 40 % leucine. Where researchers compared a high-leucine mixture with a balanced one, the extra leucine was not where the difference came from.
- Side effects are barely mentioned in these trials. A twelve-week study in older adults recorded no adverse responses in any group, with compliance above 95 %, and reviewers note that taste and the willingness to keep taking something matter as much as the formula.
- A good deal of the research is clinical rather than everyday: trials before and after knee replacement, after a hip fracture, and in people with long-term lung conditions make up a large part of it. Several products described as EAA-based also contain whey protein, creatine or vitamin D, so a headline about essential amino acids may not be about the free amino acids alone.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (15 studies)
- Effects of Resistance Exercise and Essential Amino Acid Intake on Muscle Quality, Myokine, and Inflammation Factors in Young Adult Males. (2024, randomised trial)
- Leucine-Enriched Essential Amino Acids Improve Recovery from Post-Exercise Muscle Damage Independent of Increases in Integrated Myofibrillar Protein Synthesis in Young Men. (2020, randomised trial)
- Effectiveness of essential amino acid supplementation in stimulating whole body net protein anabolism is comparable between COPD patients and healthy older adults. (2017, randomised trial)
- Activation of mTORC1 by leucine is potentiated by branched-chain amino acids and even more so by essential amino acids following resistance exercise. (2016, randomised trial)
- High anabolic potential of essential amino acid mixtures in advanced nonsmall cell lung cancer. (2015, randomised trial)
- Essential Amino Acid and Tea Catechin Supplementation after Resistance Exercise Improves Skeletal Muscle Mass in Older Adults with Sarcopenia: An Open-Label, Pilot, Randomized Controlled Trial. (2023, randomised trial)
- Effect of Aerobic Exercise Training and Essential Amino Acid Supplementation for 24 Weeks on Physical Function, Body Composition, and Muscle Metabolism in Healthy, Independent Older Adults: A Randomized Clinical Trial. (2019, randomised trial)
- Effects of Protein, Essential Amino Acids, B-Hydroxy B-Methylbutyrate, Creatine, Dehydroepiandrosterone and Fatty Acid Supplementation on Muscle Mass, Muscle Strength and Physical Performance in Older People Aged 60 Years and Over. A Systematic Review on the Literature. (2018, systematic review)
- Daily Consumption of a Specially Formulated Essential Amino Acid-Based Dietary Supplement Improves Physical Performance in Older Adults With Low Physical Functioning. (2021, randomised trial)
- Essential amino acid formulations to prevent mitochondrial dysfunction and oxidative stress. (2021, review)
- Muscle Protein Synthesis and Whole-Body Protein Turnover Responses to Ingesting Essential Amino Acids, Intact Protein, and Protein-Containing Mixed Meals with Considerations for Energy Deficit. (2020, review)
- Molecular mechanism and therapeutic significance of essential amino acids in metabolically associated fatty liver disease. (2024, review)
- Glutamine and glutamate: Nonessential or essential amino acids? (2015, review)
- The efficacy of essential amino acid supplementation for augmenting dietary protein intake in older adults: implications for skeletal muscle mass, strength and function. (2021, review)
- Effects of essential amino acid (EAA) and glutamine supplementation on skeletal muscle wasting in acute, subacute, and postacute conditions. (2024, review)
How much does EAA cost?
That depends on the form and the pack, so we work out the price of the same dose of every EAA product we can find and rank them.