In 30 seconds
- They switch on muscle protein synthesis, 22% more than placebo; to build muscle, they work better alongside your protein, which provides all 9 essential amino acids.
- Muscle soreness is where most studies are in their favour: a meta-analysis of 18 trials found less pain between 24 and 96 hours.
- One serving a day, before, during or after training: there is no clearly better time.
- If you already reach your daily protein, you are already getting BCAAs from your food.
BCAAs have been among the most widely known supplements for decades. All sorts of things are attributed to them: more muscle, less soreness, more stamina. We sell BCAAs, and that is precisely why we are telling you what holds up.
What they are, in one sentence
Leucine, isoleucine and valine: 3 of the 9 essential amino acids, the ones your body cannot make. They are in all good-quality protein: in meat, fish, eggs and milk they make up around 25% of the amino acids 4.
What the studies say
BCAAs in three figures
What is claimed, point by point
| What is claimed | What the studies say |
|---|---|
| You build more muscle | Better alongside your protein. They switch on muscle protein synthesis, 22% more than placebo. |
| You get less muscle soreness | Yes, in the studies. Less pain between 24 and 96 hours across 18 trials. |
| You perform better in endurance | Less studied. Research has focused on muscle soreness and muscle damage. |
Sources: Salem et al., 2024; Jackman et al., 2017; Wolfe, 2017; NIH.
“You build more muscle”
Taking 5.6 g of BCAAs after strength training increased muscle protein synthesis by 22% compared with placebo 2. To build muscle, however, you need all 9 essential amino acids, not just 3. One review concluded that BCAAs on their own cannot sustain an increase in muscle protein synthesis 3.
In plain terms: if you want to build muscle, start with the total protein in your day.
“You get less muscle soreness”
This is where most studies are in their favour. A meta-analysis of 18 trials found that BCAAs reduced muscle soreness at 24, 48, 72 and 96 hours after exercise that damages muscle 1.
How they were taken in the studies
The 18 trials used very different regimens, and that made it possible to see what worked best 1:
| What | In the studies | What worked best |
|---|---|---|
| Amount per day | From 3.15 to 29.3 g | More than 5 g a day, for muscle soreness |
| How many days | From 1 to 28 days | High doses for more than 7 days, for CK |
| Muscle soreness | Less pain at 24, 48, 72 and 96 hours | The biggest effect, at 48 and 72 hours |
| Blood markers of muscle damage | CK lower at the end and at 72 hours; LDH unchanged | — |
Source: Salem et al., 2024 (meta-analysis of 18 trials).
The authors' practical takeaway: for muscle soreness, more than 5 g a day; to lower CK, a marker of muscle damage in the blood, high doses for more than 7 days 1. In other words, taking them only on the day of a hard session is not enough: consistency counts.
There are caveats too. The other enzyme measured to assess muscle damage, LDH, did not change, and the authors themselves note that the results may depend on how each study was designed, on whether the participants were trained and on their sex 1.
“You perform better in endurance”
The idea was that BCAAs delayed fatigue. Research has focused mainly on muscle soreness and muscle damage, and that is where the strongest results are 4.
So when do they make sense?
- If you want to look after muscle soreness: this is where most studies are in their favour.
- If you like having something flavoured while you train, with no added sugars. If you train without breakfast, see BCAAs before fasted training.
- If you are not reaching your protein, start there instead: food or a complete protein shake. We explain it in BCAAs or protein.
How to take them
How BCAAs fit into your day
How to take them
One serving a day, before, during or after training: no moment is clearly better. According to the US National Institutes of Health, up to 20 g a day has shown no safety concerns in studies lasting up to 6 weeks 4.
Frequently asked questions
Do BCAAs help you build muscle?
They stimulate muscle protein synthesis, 22% more than placebo in one trial. To build muscle you need all 9 essential amino acids: what matters most is the total protein in your day.
Do BCAAs get rid of muscle soreness?
This is where most studies are in their favour: a meta-analysis of 18 trials found less muscle soreness between 24 and 96 hours after exercise.
When should you take BCAAs?
Before, during or after training. No moment is clearly better: choose whichever suits you.
Is it worth taking BCAAs if I already take protein?
If you already reach your daily protein, you have the foundation for building muscle. BCAAs fit in if you like having something flavoured and sugar-free while you train, or because of the studies on muscle soreness.
How many grams of BCAAs should you take a day?
The studies on muscle soreness used 3 to 29 g a day, and doses above 5 g a day worked best. According to the US National Institutes of Health, up to 20 g a day has shown no safety concerns in studies lasting up to 6 weeks.
Sources
- Salem A, Ben Maaoui K, Jahrami H, et al. Attenuating muscle damage biomarkers and muscle soreness after an exercise-induced muscle damage with branched-chain amino acid (BCAA) supplementation: a systematic review and meta-analysis with meta-regression. Sports Med Open. 2024;10:42. View publication
- Jackman SR, Witard OC, Philp A, Wallis GA, Baar K, Tipton KD. Branched-chain amino acid ingestion stimulates muscle myofibrillar protein synthesis following resistance exercise in humans. Front Physiol. 2017;8:390. View publication
- Wolfe RR. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? J Int Soc Sports Nutr. 2017;14:30. View publication
- Office of Dietary Supplements, National Institutes of Health. Dietary supplements for exercise and athletic performance: fact sheet for health professionals. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product. A varied and balanced diet and a healthy lifestyle are important.
