Three to Five Cups of Coffee a Day Linked to Longer Life and Lower Disease Risk, Review Finds

A cup of coffee at the kitchen table may be doing more than waking anyone up. A new review, written by two authors and covered by Medical News Today, gathers decades of research and concludes that drinking three to five cups a day is linked to a lower risk of death, type 2 diabetes, and cardiovascular disease, along with a long list of other outcomes.

The review leans heavily on cohort studies. One of them found that people drinking at least two cups daily had a 10 to 15 percent lower risk of dying from any cause. A 2019 meta-analysis found the relationship was nonlinear, with the lowest all-cause mortality at three and a half cups a day. Decaf and caffeinated coffee may both lower mortality risk, and the reduction may hold across coffee types. The review also notes that the FDA generally considers coffee healthy when it has fewer than five calories.

On specific diseases, the authors estimate that three to five cups daily may cut cardiovascular disease risk by about 15 percent. Coffee likely does not raise cancer risk and may lower it for some types, such as endometrial cancer. It may reduce chronic respiratory problems and respiratory disease mortality, and lower the risk of type 2 diabetes, apparently in both decaf and regular forms. In people who already have diabetes, one meta-analysis tied coffee to fewer cardiovascular events and lower cardiovascular and overall mortality. The liver benefit is likely smaller than experts once thought, though coffee may reduce the risk of chronic kidney disease. The review reports a 25 percent lower risk of cognitive disorders, again nonlinear, and a possible reduced risk of Parkinson's disease and its progression. A large umbrella review the authors cite concluded that benefits outweigh harms overall, with the most benefit at three to four cups a day.

The authors also point to everyday effects. Coffee may help hydration, though sometimes it increases urine output. Caffeinated coffee may improve exercise performance, mental acuity, and senses such as vision, and may help bowel function return after bowel surgery. Some data suggest lower depressive symptoms and perceived stress. Possible mechanisms include better glucose tolerance, higher activity levels linked to lower body mass index, increased fat oxidation before exercise, and reduced inflammation. For the lungs, the caffeine metabolites paraxanthine and theophylline may play a role, though smoking may mask the benefit.

Additives complicate the picture. Some research suggests sugar may cancel coffee's benefits; one study linked sugar in coffee to higher depression risk, and another found sugar offset the possible weight benefits of regular and decaf coffee. That same study found cream or whitener was not tied to greater weight gain. Small amounts of sugar and fat may leave the lower mortality risk intact, while larger amounts may erase it, although some evidence says the benefits survive sweetening.

There are drawbacks. Coffee may cost some people sleep, though timing can help. It can cause short-term blood pressure spikes, but research points to no long-term risk and possibly lower blood pressure. Moderate intake likely does not raise the risk of abnormal heart rhythms, and one trial of high caffeine doses found no induced arrhythmias. In pregnancy, some trials found no link to poor outcomes, though confounding is possible; the authors say limits may be needed, but under 200 milligrams a day likely has little impact. Heavy use may cause anxiety and panic attacks, especially in people with panic disorder, with symptoms such as high heart rate and palpitations. The authors recommend individualizing intake.

Review author Farin Kamangar, MD, PhD, told Medical News Today that decades of high-quality research on millions of people show coffee is overall beneficial. The review has limits: it is the work of two authors, the cohort studies came from the U.S., Europe, and Asia, and the mortality data covered only those regions. David Cutler, MD, a family medicine physician at Providence Saint John's Health Center in Santa Monica, who was not involved, noted that beans, roasting, additives, individual response, smoking and drinking habits, and industry funding can all muddy results, so skepticism is warranted.

Most findings remain observational. The next steps, per the source, are randomized controlled trials and Mendelian randomization studies, plus closer looks at brewing methods, coffee types, additives, and who benefits most or should be cautious.