Caffeine gets the credit for most of our morning focus, but a randomized placebo-controlled trial in middle-aged and older Japanese adults suggests matcha may offer something extra. A single caffeine dose sharpened attention, yet only continuous daily matcha intake increased work output on a stress-inducing arithmetic test. The authors credit matcha's pairing of caffeine with amino acids like L-theanine. The study has real limits, including mild lab stress, one population and no isolated theanine arm, so the takeaways come with caveats. Here is what the findings mean for matcha versus coffee, daily habits versus one-off doses, and who might benefit.
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