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Caffeine and L-theanine: why they're paired in a pre-workout

Caffeine and L-theanine are paired because researchers have repeatedly tested them together, and a meta-analysis found the combination's clearest effects were on alertness and attention-switching accuracy in the first two hours. L-theanine is an amino acid found in tea. The studies are small, mostly done in labs on mental tasks rather than workouts, and caffeine seems to drive much of the effect. Sí Quema pairs 200 mg of caffeine with 350 mg of L-theanine for focus*.

Key takeaways

  • L-theanine is an amino acid that comes from tea.
  • A 2014 meta-analysis of 11 studies found the pair's strongest evidence for alertness and attention switching.
  • The key trials used 40 to 150 mg of caffeine and about 100 to 250 mg of L-theanine.
  • Studies measured mental tasks in a lab, not training sessions.
  • Sí Quema: 200 mg caffeine + 350 mg L-theanine per scoop, 18+.

What is L-theanine?

L-theanine is an amino acid found in tea, and it's one of the tea compounds most studied alongside caffeine.

Tea naturally contains both caffeine and L-theanine, and several of the studies on the pair delivered them in tea-based drinks. A 2014 systematic review in Nutrition Reviews looked at the acute effects of these "tea constituents" on mood and thinking.

What has research found about caffeine and L-theanine together?

Several small, placebo-controlled trials found the combination improved certain attention tasks, with the most consistent results for task-switching accuracy and self-rated alertness.

Here are the main studies, in plain terms:

  • Haskell et al., 2008. Researchers tested 250 mg L-theanine and 150 mg caffeine, alone and together. The combination improved accuracy on a rapid information-processing task, sped up simple reaction time and working-memory reaction time, and increased self-rated alertness. The authors suggested drinks with both "may have a different pharmacological profile" than caffeine alone.
  • Owen et al., 2008. In 27 adults, 100 mg L-theanine plus 50 mg caffeine improved both speed and accuracy on an attention-switching task at 60 minutes and reduced distraction during a memory task.
  • Giesbrecht et al., 2010. In 44 young adults, 97 mg L-theanine plus 40 mg caffeine improved task-switching accuracy and raised self-reported alertness. There was no effect on visual search, choice reaction time or mental rotation.
  • Einöther et al., 2010. In 29 adults, the same small doses improved task switching but not intersensory attention or self-rated alertness.

When researchers pooled the evidence in the 2014 meta-analysis, the combination showed benefits within the first two hours, with the strongest evidence for alertness and attention-switching accuracy.

Does L-theanine do the work, or does caffeine?

Caffeine appears to do a lot of it.

The 2014 meta-analysis found that caffeine dose had a larger influence on the size of the effect than L-theanine dose, especially in the first hour. Two of the trials above, Giesbrecht and Einöther, didn't include a caffeine-only group, so they can't show what L-theanine adds on its own. In the Haskell study, L-theanine by itself lowered accuracy on a subtraction task; the benefits showed up with caffeine in the mix.

So the honest summary: the combination has some positive results in small trials, but the research doesn't prove L-theanine is the star.

What are the limits of this research?

The trials are small, short, and done on mental tasks in a lab, not during exercise.

  • Small samples. The trials above that reported their size tested 27 to 44 people.
  • Lower doses than pre-workouts. Caffeine ranged from 40 to 150 mg in these trials. Top-selling pre-workouts average about 254 mg, and Sí Quema has 200 mg.
  • No workouts. Participants did computer-based attention and memory tests. That tells us something about focus, not about lifting or running.

Why does Sí Quema pair caffeine with L-theanine?

Because the pair has a real body of published research behind it, including a meta-analysis, and because we wanted energy and focus from a formula with every dose on the label*.

One scoop of Sí Quema has 200 mg of caffeine and 350 mg of L-theanine, along with 500 mg of L-tyrosine, an amino acid that has been studied for cognitive performance under demanding conditions. Those amounts are printed on the label, so you can compare them to the research yourself. There are no proprietary blends.

Caffeine still affects people differently. If you're new to pre-workouts, start with half a scoop, and don't combine Sí Quema with coffee, energy drinks or other caffeine.

200 mg caffeine per serving · 18+

Curious how it feels in a real workout? Pick a flavor in the Sí Quema pre-workout collection.

Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.