Why do I say that? Simple biochemistry: it is what helps make adrenaline and dopamine. It is also a precursor to thyroid hormones (see my July 2016 blog on the thyroid).
Adrenaline helps with alertness, concentration, memory, mood, cognitive function.
Dopamine helps with happiness, motivation, appetite suppression, libido, mood, cognition function, etc.
Best taken before breakfast, 500-1500mg a day.