BCAAs - branched chain amino acids
These include leucine, isoleucine, and valine. Taking BCAAs activates the mTOR pathway. mTOR inhibition extends life span in multiple organisms. A 5 g dose is taken by athletes after a hard workout to repair muscles. But taking a 5 g dose activates the mTOR pathway. Activating the mTOR pathway may decrease lifespan.
Leucine has recently been shown to prevent sarcopenia in the elderly. However, exercise and a high protein diet also prevent sarcopenia. But the evidence that mTOR decreases lifespan in older adults convinced me to stop supplements with BCAAs over age 65.
It has also been discovered in 2021 that a daily dose of BCAAs, specifically leucine was tested, activated muscle cells in people over 27 to regain their ability to divide. In humans, muscle cells no longer divide after around age 27. So body building then only increases the size of existing muscle cells, but does not cause new cells to form. On the other hand, muscle cells which are not used die and become fat cells, which is why older athletes who stop working out look so fat.