Few things people eat or drink have been studied as closely as coffee. For decades it was treated as a vice to be kept in check. Over the last ten years, some of the largest studies in nutrition have looked at it again, following hundreds of thousands of people for a decade or more. Here are five of them, what each found, and, just as important, what none of them can tell us.
The overview: 218 meta-analyses in one paper
In 2017 a team from the University of Southampton and the University of Edinburgh published an umbrella review in the BMJ: a review of reviews. It gathered 201 meta-analyses of observational studies, covering 67 health outcomes, and 17 meta-analyses of clinical trials, covering nine.
Coffee was more often associated with benefit than with harm. The largest differences appeared at three to four cups a day compared with none: a 17% lower risk of death from any cause over the study periods (relative risk 0.83, 95% confidence interval 0.79 to 0.88) and a 19% lower risk of death from cardiovascular disease. Some of the strongest associations were with liver conditions.
The authors were just as clear about the limits. Most of the evidence was rated low or very low quality, because almost all of it was observational. And two groups stood apart: in pregnancy, high intake was associated with low birth weight, preterm birth and pregnancy loss, and in women, with a higher risk of fracture. Their conclusion: coffee appears safe within usual levels of intake, outside pregnancy and for women at risk of fracture, and only randomized trials can show cause.
Half a million people, eleven years
In 2022, researchers at Queen Mary University of London and Semmelweis University in Budapest analyzed the UK Biobank: 468,629 adults with no heart disease when they joined, followed for a median of eleven years.
People who drank half a cup to three cups a day had a 12% lower risk of death from any cause than non-drinkers (hazard ratio 0.88, 95% confidence interval 0.83 to 0.92), a 17% lower risk of cardiovascular death (0.83, 0.74 to 0.94) and a 21% lower risk of stroke (0.79, 0.63 to 0.99).
The study added something rare: cardiac MRI scans of 30,650 participants. Regular coffee drinkers had slightly larger, well-functioning hearts and less stiff arteries, a pattern the authors read as healthy adaptation rather than harm.
The cup as people drink it
Harvard Health Publishing reported on a second UK Biobank analysis, published in the Annals of Internal Medicine in 2022, that asked a practical question: does it matter what goes into the cup? It followed more than 170,000 adults, on average 56 years old and free of cancer and heart disease at the start, for about seven years.
Those who drank one and a half to three and a half cups a day, unsweetened or with about a teaspoon of sugar per cup, were up to about 30% less likely to die during the study than non-drinkers. Caffeine content made no difference: decaffeinated coffee showed the same pattern. Above four and a half cups, the association weakened.
Two cautions came with it. A teaspoon is less sugar than many people add, so the result says nothing about sweeter habits. And, like every study here, it shows an association, not a cause.
Two years of life expectancy
In 2025, Public Health Nutrition published an analysis of the US National Health and Nutrition Examination Survey from 2001 to 2018: 43,114 adults, followed for a median of 8.7 years, during which 6,234 died.
Instead of risks, the authors calculated life expectancy. At the age of 50, people who drank no coffee could expect to live another 30.1 years. Those who drank one to two cups a day could expect 32.1: about two years more. About 30% of that difference was traced to fewer deaths from cardiovascular disease.
The details matter. The gain was seen with unsweetened coffee, not with sweetened. Caffeinated coffee showed its largest association at one to two cups, decaffeinated only above three. And intake was measured by one or two 24-hour dietary recalls, a snapshot rather than a lifetime.
People who already have heart disease
The same survey data were used by a study in Nutrition, Metabolism and Cardiovascular Diseases in 2025, but for a different group: 7,369 adults already living with cardiovascular or cerebrovascular disease, such as heart disease or a past stroke.
Coffee drinkers had a 25% lower risk of death from any cause than those who drank none (hazard ratio 0.75, 95% confidence interval 0.59 to 0.96), and those who drank one to three cups a day a 35% lower risk of cardiovascular death (0.65, 0.43 to 0.98). The intervals are wide, with upper limits close to no difference at all, which is what a smaller group gives.
What none of these studies can say
Every study here is observational. It compares people who drink coffee with people who do not, and the two groups differ in more than coffee. Researchers adjust for smoking, alcohol, weight, income and illness, but no adjustment is complete. Some people stop drinking coffee because they are already unwell, which can make coffee look better than it is. Intake is mostly self-reported. None of this proves that coffee makes anyone live longer, and none of it means that someone who does not drink coffee should start.
What the research does show, consistently and across very large populations, is that moderate coffee drinking, roughly one to four cups a day, is compatible with good health for most adults. The European Food Safety Authority considers up to 400 mg of caffeine a day safe for healthy adults, and up to 200 mg a day in pregnancy.
Business Insider took up the same question for a general audience in March 2026.
Why this matters to us
Coffee was never the problem. That is the premise of Fairytale + Grey, and it is what this research, read carefully, supports. It is also why the coffee in every formula is left as coffee: 100% Arabica. What we add is chosen on a stricter standard, and named, with what it is for, on The F+G Formula.