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Branched chain amino acids are a commonly used nutritional supplement – but, asks dietitian Ashleigh Feltham, are they actually necessary?

You could easily spend your weekly pay packet if you bought every supplement available on the market claiming to enhance your performance and results.

A common supplement you have no doubt encountered is BCAA: branched chain amino acids. This supplement contains types of amino acids (lysine, leucine and valine) which your body cannot make by itself, and so you need to include these amino acids in your diet. But do you need to drink them as a supplement?

The answer depends on your circumstances:


  1. If you are training on an empty stomach, BCAAs may help the amino acids reach your muscles fast and assist your results if you have specific body composition goals.
  2. If you are an endurance athlete, BCAAs may improve performance because it can help reduce fatigue. BCAAs compete for the same transporter required to transport the amino acids from your blood to your brain with another hormone called tryptophan. This hormone produces serotonin which, when inhibited, may help endurance athletes push through fatigue.
  3. You are not meeting your protein needs from your diet and need the extra help achieving this (often in cases of very high protein requirements, e.g. weightlifters).


  1. If you are a regular gym ‘athlete’ eating a balanced diet which includes protein sources, then you will be including all the BCAAs you need for results and health, so BCAA supplements may be a waste of money.
  2. If you take whey protein, this already contains BCAAs, so there is no point in doubling up on the same ingredient. Select the one which meets your goals and needs the best, or it’s like paying rent twice in the same week.
  3. BCAAs need a transporter to be taken from your blood to your brain. BCAAs compete with two other types of protein called tryptophan and tyrosine in your body when crossing from the blood to the brain to create signals and messages to your body. Tryptophan is a protein which is converted to serotonin (feel good hormone) and melatonin (needed for sleep) and tyrosine increases the performance enhancing hormone dopamine. If you overdo the BCAAs, you may deprive tryptophan and tyrosine of their optimal transportation, and thereby prevent yourself from getting a good night’s sleep and enhanced performance abilities.

Take home message: BCAAs may help your performance, but it depends of your level of activity, if you are eating on an empty stomach, what other supplements you are taking and your overall diet. If you need more information specific to your individual circumstances, seek the support of an Accredited Practicing Dietitian.

Ashleigh Feltham is an Accredited Practising Dietitian and owner of Feed Your Future Dietetics. She is also an experienced personal trainer and group fitness instructor. Follow her on Instagram and Facebook

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