Green tea has less caffeine than coffee, but L-theanine changes how your body processes it entirely — and that difference matters more than the number.
Source: https://nevisan.in/journal/green-tea-vs-coffee-caffeine
May 2026 · Nevisan Tea Journal
Green tea has less caffeine than coffee, but L-theanine changes how your body processes it entirely — and that difference matters more than the number.
The standard caffeine comparison goes like this: coffee has 80–120mg per cup, green tea has 20–50mg. Green tea wins on lower caffeine. End of discussion. But this framing misses what actually matters — not how much caffeine you’re taking in, but what that caffeine does to your body.
Green tea contains L-theanine, an amino acid that modulates the effect of caffeine in a specific way. L-theanine promotes alpha-wave activity in the brain — the mental state associated with relaxed focus, the kind you get in the first hour of a productive morning before anything stressful has happened. When combined with caffeine, L-theanine smooths out the stimulant curve: slower rise, longer plateau, gentler descent. No spike, no crash.
Coffee delivers caffeine alone (unless you add it), which is why many people feel jittery after their second cup and then hit an energy wall in the early afternoon. The crash is not a caffeine deficiency — it’s adenosine (the sleep signal) flooding back in after caffeine’s blocking effect fades suddenly.
If you drink green tea instead of coffee for two weeks, most people report clearer, more sustained focus in the morning and less reliance on a second or third cup to maintain it. Nevisan’s single-origin Assam green teas use whole leaf, which retains more L-theanine than broken-leaf or powdered formats. Brew at 80°C for two minutes — this is where the ratio of caffeine to L-theanine is optimal.