L-theanine

Useful for: Performance anxiety, like doing well in a tense meeting or on a test. It may reduce the body’s stress response during those tasks. Effects are mild. It may also help with attention and reaction time.

What’s the dose? 200mg; many studies suggest it can create a calm but alert state in about an hour. (It’s one of my favourite supplements.) Take note: L-theanine is in green and black teas, but there’s only about 6mg of L-theanine in a cuppa.