Coffee is not the enemy and this is not an argument against it. But there is one specific job caffeine does not do, and it explains a pattern a lot of people are stuck in.
What caffeine actually does
Adenosine builds up through the day and produces the feeling of tiredness. Caffeine occupies the receptors adenosine would otherwise bind to, so the signal does not land. The tiredness is still being generated — it is just not being received for a while.
That is genuinely useful. It is also the whole mechanism, which is why the effect shrinks as tolerance builds and why the pattern reasserts itself later in the day.
What it does not do
Caffeine does not supply the brain with anything. It blocks a signal.
Attention itself runs on acetylcholine, a neurotransmitter the brain uses for focus and memory — and the body builds acetylcholine from choline, a nutrient that comes from food. Blocking a tiredness signal and supplying the raw material for attention are different operations. Caffeine does the first one well and the second one not at all.
Which is why the usual escalation — a second coffee, then an energy drink at three, then a pre-workout taken at a desk — tends to deliver less each time.
Where the raw material comes from
Choline is concentrated in eggs and organ meats. Both spent decades out of fashion, and unlike the nutrients that got famous, choline was never fortified into anything and never had a campaign. Habitual intake in the United States now sits below the Adequate Intake;2 in a 2025 study of adults 65 and over, only 10% met it.3
The part where most supplements fall down
Most products that say "choline" use choline bitartrate — 458 of the 635 on-market labels naming choline, in the National Institutes of Health Dietary Supplement Label Database — real choline, chosen because it is cheap. In one 2026 trial in healthy adults it did not improve working-memory performance against placebo.4 Alpha-GPC is the form behind the published trials, and it costs meaningfully more per gram, which is why cheaper products dominate the shelf.
Sources
- Google Keyword Planner, US search volumes, pulled August 2026.
- Trujillo-Gonzalez et al., American Journal of Clinical Nutrition, 2026 — habitual US choline intake remains below the Adequate Intake.
- Suzuki et al., Journal of Food Composition and Analysis, 2025 — n=203, aged 65 and over; 10% met the Adequate Intake.
- Dumas et al., 2026 — n=20 healthy adults, 1,650 mg choline bitartrate; no working-memory performance difference against placebo.
- Research in healthy adults: Nutrients 2024 (315 and 630 mg); a 2017 dose-comparison study (250 and 500 mg); a 2023 trial in cyclists (300 mg).
Full detail, with the population studied in each, on the sources page.