L-theanine
Silver· human dataAlso known as: Theanine
A tea-derived amino acid best known for taking the edge off caffeine.
What it is
L-theanine is an amino acid found naturally in tea, associated with a state of relaxed alertness. It is best known for being paired with caffeine to smooth out the jitters.
What the evidence shows
Calm focus, alone. Silver· human data The evidence points to a subtle calming effect on attention rather than anything dramatic. It is not a sedative and doesn't typically cause drowsiness.
Paired with caffeine. Silver· human data Some studies support smoother, less jittery attention from the caffeine-plus- theanine combination than caffeine alone, though effects are modest.
Who it suits
People who like caffeine's focus but dislike its edge, and anyone after a gentle attention aid with a good tolerability profile.
Practical notes
It is one of the better-tolerated supplements and is commonly taken alongside coffee or a pre-workout. If caffeine timing is your real issue, our caffeine calculator shows how long it lingers in your system.
Sources
Frequently asked questions
- What does L-theanine do?
- Found naturally in tea, it's associated with a state of relaxed alertness. The preliminary evidence points to a subtle calming effect on attention rather than anything dramatic.
- Why is it paired with caffeine?
- The popular combination aims to keep caffeine's focus and alertness while taking the edge off its jitters and anxiety. Some studies support smoother attention from the pair than caffeine alone, though effects are modest.
- Will it make me drowsy?
- It isn't a sedative and doesn't typically cause drowsiness at common amounts. The goal is calm focus, not sleep. It's one of the gentler, better-tolerated supplements.
Related calculators
Related supplements
Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.
Last reviewed: