Food · 4 min read ·

Coffee: how much is just right?

It wakes you up, helps in training and maybe even your health. Just not in the evening. What do we know about caffeine?

In a nutshell

1How much is safe

Strong evidence 400 mg a day The European Food Safety Authority (EFSA) considers up to 400 mg of caffeine a day, and up to 200 mg at a time, safe for healthy adults. For pregnant women, up to 200 mg a day is fine.1

A cup of filter coffee or an espresso has roughly 80–90 mg of caffeine, but it varies a lot with the type and how it's made.2

2Coffee and health

Moderate evidence 3–4 cups A review of more than 200 meta-analyses: drinking coffee was more often linked to benefit than to harm; the lowest risks were at around 3–4 cups a day. But these are mostly observational studies — association does not mean causation.5
Moderate evidence The exceptions: in pregnancy, coffee was linked to miscarriage, low birth weight and preterm birth, and in women to a higher risk of fractures.5

3Caffeine and sport

Strong evidence 3–6 mg/kg Doses like these (roughly 200–400 mg for a 70 kg person) about an hour before exercise reliably improve performance — most of all in endurance, with smaller effects on strength, sprints and jumps. Very high doses don't help more, they just bring more side effects.3

4Sleep

Moderate evidence −1 hour of sleep In an experiment, 400 mg of caffeine cut sleep by more than an hour even when taken 6 hours before bedtime — and people didn't even notice.4 In more sensitive people, as little as 100 mg in the evening can worsen sleep.1

Related articles: Hydration.

What to take from this

Sources

Written on , based on studies available at that date. Newer research may change the conclusions.

  1. EFSA NDA Panel (2015). Scientific Opinion on the safety of caffeine. EFSA Journal 13(5):4102. doi.org/10.2903/j.efsa.2015.4102
  2. EFSA — Caffeine topic page (how much caffeine is in drinks). efsa.europa.eu
  3. Guest N. S. et al. (2021). International society of sports nutrition position stand: caffeine and exercise performance. JISSN 18:1. doi.org/10.1186/s12970-020-00383-4
  4. Drake C. et al. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine 9(11):1195–1200. pmc.ncbi.nlm.nih.gov/articles/PMC3805807
  5. Poole R. et al. (2017). Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. BMJ 359:j5024. doi.org/10.1136/bmj.j5024

This is general information and does not replace a doctor. If you get palpitations, anxiety or insomnia, cut down on caffeine and talk to a doctor.