L-Theanine and Caffeine

L-theanine is an amino acid found in tea. It's often paired with caffeine in a 2:1 ratio (twice as much L-theanine as caffeine).

What the studies show

• Owen et al., 2008: 100 mg L-theanine + 50 mg caffeine improved accuracy on attention-switching tasks and reduced susceptibility to distraction vs placebo (Nutritional Neuroscience).
• Foxe et al., 2012: a 2:1 combination improved some attention measures, but the paper reported no benefit beyond either compound alone on key measures (Neuropharmacology).

How to use the evidence

• Check labels for actual milligrams of both. "Contains L-theanine" without a dose can't be compared with research.
• A 2:1 ratio at 100 mg theanine / 50 mg caffeine is what was studied.
• Evidence is short-term and in small samples.