Excess consumption of leucine supplement can leads to brain damage and liver disease.(2)
(1,2) https://selfhacked.com/blog/leucine-health-benefits-side-effects/
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NutriBuddy™ 
Description
L-Leucine is a white crystalline essential amino acid which is obtained by the hydrolysis of dietary protein (as of eggs, soy, or fish) and plays an important role in many physiological functions.