Matcha questions answered

One canonical page per question, answered in the first paragraph and backed by sources. Caffeine questions have their own full guide at how much caffeine is in matcha.

What is matcha made of?Matcha is made of one ingredient, shade-grown green tea leaves called tencha, steamed, dried and stone-ground to powder. How it is grown and processed.
Is matcha good for you?What the evidence says about matcha and health (antioxidants, L-theanine and caffeine), and where the claims outrun the research. Balanced, sourced answers.
How do you make matcha?How to make matcha at home: sift 2 grams, add 70 to 80 degree water, whisk in a W motion to a foam. Traditional method, no-whisk shortcuts and latte steps.
Where does matcha come from?Matcha's origins in Song dynasty China and its refinement in Japan, why Uji and Nishio dominate production today, and how matcha reached New Zealand cafes.
Where can you buy matcha in NZ?Where to buy matcha in New Zealand: what New World, Woolworths, Pak'nSave, Kmart and Chemist Warehouse typically stock, the NZ online matcha brands, and what to check before buying.