The L-Theanine + Caffeine Stack Isn't News. The Optimal Ratios Are.

If you've spent any time in the nootropics space, you've heard about L-Theanine and caffeine. It's the most well-studied cognitive stack in existence — smooth focus without the jitters. But here's what most people get wrong: they're using a 1:1 ratio because that's what some blog told them in 2019.

Recent research — specifically a 2024 meta-analysis published in Nutritional Neuroscience — suggests the optimal ratio is closer to 2:1 (L-Theanine to caffeine) for sustained cognitive performance, and potentially 3:1 for anxiety-prone individuals. The difference in subjective focus quality between 200mg/200mg and 400mg/200mg is not subtle.

At NooStack, we're building the CPI (Cognitive Performance Index) to actually measure these differences. Not with vibes — with standardized reaction time tests, working memory assessments, and self-reported focus scores tracked over time. The goal is to move nootropics from "I think this works" to "here's the data showing it works, at this dose, for this person."

The supplement industry has a data problem. Everyone's selling stacks, nobody's measuring outcomes. That's the gap we're closing.