Ingredient guide
What is L-theanine, and why pair it with caffeine?
The amino acid in tea leaves that explains why a cup of green tea feels different from a shot of espresso.
4 min read
L-theanine is an amino acid found almost exclusively in tea leaves (and a few mushrooms). It isn't a stimulant and it isn't a sedative — which is exactly why it shows up next to caffeine on so many labels.
What it is
Camellia sinensis — the plant behind green, black and white tea — produces L-theanine in its leaves and roots. It contributes to the savory, rounded taste described as umami in high-grade green teas. When you drink tea, you get caffeine and L-theanine together; when you drink coffee, you get caffeine largely on its own.
Why it's paired with caffeine
The pairing is the whole point. Caffeine and L-theanine are often combined because people describe the combination as feeling steadier than caffeine alone — alert without the jittery edge. It is the most common explanation offered for why a strong cup of green tea feels different from an equally strong cup of coffee, even at similar caffeine levels.
Ratios vary by product. A roughly 1:1 ratio of L-theanine to caffeine is a common formulation choice.
How much is in a can of Cómo No
- 100mg L-theanine per can
- 100mg naturally sourced caffeine — 80mg from green tea, 20mg from guaraná
- Zero sugar, zero calories, six ingredients
That is a 1:1 ratio of L-theanine to caffeine, in a caffeinated sparkling water rather than a syrupy energy formula.
Common questions
Will L-theanine make me sleepy?
It is not a sedative. It is included for the way it rounds out caffeine, not to make you drowsy.
Can I get it from tea instead?
Yes — brewed green tea contains both L-theanine and caffeine naturally, though amounts vary widely with leaf, steep time and temperature.
Is it safe?
L-theanine is widely consumed in tea. As with any supplement or functional ingredient, if you are pregnant, nursing, taking medication or managing a health condition, check with your physician first.