Coffee & Health:
The Science in a Cup
A few decades ago, doctors filed coffee alongside smoking and drinking as habits to cut back on. Today, a growing stack of large studies tells a very different story. This issue pours the most important research from 2024–2026 into one cup: how much to drink, when to drink it, how to brew it and who should go easy.
At a glance: four numbers
Remember these four, then read on.
Editor’s note: Most studies in this issue are long-term cohort (observational) studies. They show an association, not proof of cause and effect. DECAF is a rare randomized controlled trial. We’ve rated the strength of evidence next to every finding. Use them to understand your own cup, not as medical advice.
The takeaways: how many do you already follow?
Tap each habit you already have and score your coffee routine.
The health wheel: eight “notes” coffee leaves on your body
Like a tasting wheel, but for your health. Tap any segment to see the latest evidence.
Research timeline: how science changed its mind
Filter by topic and tap a study to expand it. Red dots mark randomized controlled trials.
Dates refer to journal publication or conference presentation.
Caffeine calculator: how much is left at bedtime?
Caffeine has a half-life of roughly 5–6 hours, and it varies a lot from person to person. Add today’s drinks to see the curve in your body.
1. Today’s drinks
2. About you
Caffeine per drink is a typical estimate and varies widely with bean, cup size and brewing. The model is a simplified one-compartment curve (peak at about 45 minutes) meant for intuition only. “Last cup by” follows a sleep meta-analysis that found a standard coffee (about 107 mg) needs to be finished at least 8.8 hours before bed to avoid measurably disrupting sleep.
Brewing and cholesterol: what a paper filter is worth
Cafestol, an oily compound in coffee beans, raises LDL (“bad”) cholesterol, and a paper filter traps almost all of it.
Cafestol per cup (mg, estimated)
Values are common estimates from published sources; “≈” marks rough figures. A single espresso is small, but several a day add up. Decaf contains cafestol too, so what matters is the brew method, not the caffeine.
of cafestol caught by a paper filter
In a Dutch randomized trial, people drinking almost 4 cups of unfiltered coffee a day for 11 weeks ended up with LDL about 16 mg/dL higher than those drinking filtered coffee.
In a small switch-and-switch-back study, about nine in ten participants saw LDL fall after moving to filtered coffee, then rise again when they went back.
Our advice: If your cholesterol runs high, make pour-over or drip your everyday brew, and save the French press and Turkish coffee for the occasional ritual.
Myth or fact: the coffee claims you’ve heard
Tap a card to flip it and see what the research says.
Who should cut back: a different line for different people
The 400 mg figure applies to healthy adults who aren’t pregnant. The groups below need a lower line.
🤰Pregnancy and breastfeeding<200 mg/day
🎒Children and teens≤100 mg/day
🌙Poor sleepers and anxious typesNo afternoon cups
🫀High cholesterolUse paper filters
💊Long-term medicationAsk your pharmacist
⚡Big single doses≤200 mg at once
Quiz: how health-savvy is your coffee habit?
Five questions to check how much of this issue stuck.
Sources
This issue draws on the following public reporting and study summaries.
- Coverage of “Coffee and Tea Intake, Dementia Risk, and Cognitive Function” (JAMA, Feb 2026)Pharmacy Times; see also GPnotebook summary
- Coffee and dementia riskGPnotebook (summary of the 2026 JAMA data)
- The DECAF Randomized Clinical TrialJAMA 2026;335(4):317–325 (University of Adelaide library)
- DECAF: Daily Coffee, Not Abstinence, Beneficial for AF PatientsTCTMD, Nov 2025
- There’s a link between coffee and the microbiomeUniversity of Trento press release (Nature Microbiology, 2024)
- Coffee Boosts Beneficial Gut BacteriumScientific American
- Morning coffee habit may be tied to longer life and healthier heartABC News (European Heart Journal, Jan 2025)
- Should daily coffee intake be part of a healthy diet?Hospital Healthcare (UK Biobank / ACC 2022)
- Drinking coffee daily tied to healthy aging among womenNewsNation (ASN 2025, Nurses’ Health Study)
- Long-term coffee (caffeine) drinking and mortalityGPnotebook (incl. Annals of Internal Medicine 2022)
- How Much Caffeine Is Too Much? The Limits by Who You AreSummary of FDA / EFSA / Health Canada / ACOG limits
- Is Caffeine Bad for You? Dose, Heart, Sleep and PregnancyIncludes the Gardiner 2023 sleep meta-analysis
- Can caffeine raise your LDL cholesterol?CSPI
- How coffee raises your cholesterolCafestol estimates by brew method
- Science may finally have made up its mind about coffee’s health benefitsScientific American
Disclaimer: This special is for general information and reading only and is not medical, nutritional or health advice. Most studies cited are observational and show associations, not cause and effect. If you have heart disease, are pregnant or take long-term medication, talk to your doctor before changing your diet.
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