Evidence-Based Ingredients

PIQ contains L-theanine, an amino acid that has been the subject of extensive scientific research, particularly when studied in combination with caffeine. While we cannot make medical or health claims about our product, we can direct you to the independent research.

Below, we've compiled peer-reviewed studies examining L-theanine and caffeine. These studies were conducted by independent researchers and published in scientific journals. We encourage you to review them yourself. These studies are provided for educational purposes only.

A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and mood

Found that L-theanine eliminated caffeine's vasoconstrictive effects (narrowing of blood vessels) while preserving all cognitive benefits, and improved accuracy on cognitively demanding tasks.

https://pmc.ncbi.nlm.nih.gov/articles/PMC4480845/

The effects of L-theanine, caffeine and their combination on cognition and mood

Demonstrated that L-theanine + caffeine improved reaction time and working memory accuracy while reducing headache and tiredness ratings that often accompany caffeine alone.

https://pubmed.ncbi.nlm.nih.gov/18006208/

The combined effects of L-theanine and caffeine on cognitive performance and mood

Showed that L-theanine + caffeine improved both speed and accuracy on attention tasks and reduced susceptibility to distracting information compared to caffeine alone.

https://pubmed.ncbi.nlm.nih.gov/18681988

Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis

Meta-analysis of 11 randomised controlled trials showing the L-theanine + caffeine combination produces superior alertness and attention compared to either compound alone.

https://pubmed.ncbi.nlm.nih.gov/24946991/

L-Theanine reduces psychological and physiological stress responses

Demonstrated that L-theanine reduced stress-induced increases in heart rate and physiological stress markers, directly countering caffeine's stimulatory effects.

https://pubmed.ncbi.nlm.nih.gov/16930802/

Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together

Showed that L-theanine antagonized (blocked) caffeine's blood pressure increases, preventing the cardiovascular side effects of caffeine while maintaining alertness benefits.

https://pubmed.ncbi.nlm.nih.gov/17823847/

L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance

Demonstrated that the combination modulates brain wave activity (increased alpha waves associated with relaxed focus) and improved attention task performance beyond caffeine alone.

https://pubmed.ncbi.nlm.nih.gov/18296328/

High-dose L-theanine–caffeine combination improves neurobehavioural and neurophysiological measures of selective attention in acutely sleep-deprived young adults

Found that L-theanine + caffeine improved reaction time and attention even in sleep-deprived subjects, showing the combination works better than caffeine alone under cognitive stress.

https://pmc.ncbi.nlm.nih.gov/articles/PMC12491391/

Effect of single or combined caffeine and L-Theanine supplementation on shooting and cognitive performance in elite curling athletes

Found the caffeine + L-theanine combination improved shooting accuracy and cognitive test performance better than caffeine alone in precision athletes.

https://pmc.ncbi.nlm.nih.gov/articles/PMC10566444/

Effects of l-theanine–caffeine combination on sustained attention and inhibitory control among children with ADHD: a proof-of-concept neuroimaging RCT

Neuroimaging study showing L-theanine + caffeine improved total cognition composite scores and demonstrated measurable brain activity changes in attention networks.

https://www.nature.com/articles/s41598-020-70037-7

Effects of Tea or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood: A Systematic Review and Meta-Analysis

2025 comprehensive systematic review confirming cognitive and mood benefits of L-theanine with caffeine across multiple studies.

https://academic.oup.com/nutritionreviews/article/83/10/1873/8123998

The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness

https://pubmed.ncbi.nlm.nih.gov/21040626/

These statements have not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease. Research is provided for educational purposes only.