I read often posts about how much BCAA’s should be taken and how important they are.
BCAA’s are necessary to grow muscle, but only the initiation. All the other amino acids are needed too to make the muscle truly grow.
[…] they have presented us with intriguing evidence that despite the potent anabolic properties of leucine supplementation, a full complement of essential amino acids, in a rapidly digestible form of whey, is required to facilitate the anabolic actions of leucine leading to muscle protein accretion and hypertrophy. […]
– J Physiol 590.9 (2012) pp 2065–2066
Leucine acts on the initiation of the anabolic pathway and thus is only a proxy for digested protein. Just to ingest Leucine (or BCAAs) means you push the button, but you don’t have any current afterwards to have the light. There seems to be also an “upper limit” (aka. muscle full effect) when it comes to overall protein/ leucine ingestion.
Therefore it’s not okay to replace a “full” protein like whey with BCAAs only if you want to grow bigger. You may initiate the growth with BCAAs, but you must deliver the other amino acids too to reap the benefits of your action.
However, there’s a downside to high BCAA ingestion too: It can increase the risk of ALS (amyotrophic lateral sclerosis).
[BCAA] leads to a hyperexcitability of the cells: they fire more action potentials than control cells for the same amount of excitation (Pieri et al., 2009). In the present work, Carunchio et al. show that a diet enriched in BCAAs also induced a hyperexcitability of the cortical motoneurons. This effect was dose dependent and specific to BCAAs, as diet enriched with non-branched-chained amino acids such as alanine or phenylalanine did not alter the excitability of the cells.
– Manuel et al. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049458/
BCAAs are not the magic supplement. They are okay to use, but not needed in insane amounts.