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Daily coffee may protect the heart in unexpected way, study suggests
Trial contradicts decades of medical advice telling atrial fibrillation patients to avoid caffeine
Published: November 11, 2025
Patients with irregular heartbeats — caused by atrial fibrillation (AF), the most common heart rhythm disorder — have historically been warned to limit or eliminate caffeine.But a new study suggests that moderate coffee consumption could actually reduce recurrence of AF after treatment.Researchers at University of California, San Francisco enrolled 200 adults with persistent AF who were scheduled for cardioversion, a procedure that restores normal heart rhythm.Participants were randomly assigned to one of two groups. One group continued to drink caffeinated coffee daily (at least one cup), while the other was instructed to abstain completely from coffee and other caffeine-containing products for six months.The primary goal was to determine whether AF kept happening, based on electrocardiogram recordings lasting at least 30 seconds. The researchers also monitored for symptom severity and adverse events.At the six-month mark, AF occurred again in 47% of participants who continued drinking coffee, compared with 64% in those who didn’t. This translated to a 39% lower relative risk of recurrence among coffee drinkers.No significant difference in side effects or adverse events was observed between groups, suggesting that moderate coffee intake was well-tolerated.The findings imply that staying away from coffee may not be necessary for patients recovering from AF — and, in some cases, could even be counterproductive.Results of the randomized clinical trial — called "DECAF" (Does Eliminating Coffee Avoid Fibrillation?) — were published in JAMA."While we were not surprised by the results, we were surprised at the magnitude of the apparent protective effect," corresponding author Dr. Gregory Marcus, associate chief of cardiology for research at UCSF Health, told Fox News Digital. "Patients [who have] atrial fibrillation or are worried about developing it who currently enjoy drinking caffeinated coffee should be reassured it is fine to do so," added Marcus, who is also a professor of medicine at UCSF. More research is needed to confirm these findings, according to the researchers."We will now be seriously considering whether consuming caffeinated coffee might actually be a lifestyle factor that helps our atrial fibrillation patients," Marcus said.Potential limitations
The study did have some limitations, the researchers acknowledged."It is important to keep in mind that we only enrolled people who had regularly consumed caffeinated coffee at some point in the last five years, and they needed to be willing to be randomized to potentially go without it," Marcus noted. People who do have a caffeine-triggered type of atrial fibrillation and decided not to participate would therefore not have been represented in these findings."It’s also possible that people who drink many cups of caffeinated coffee a day were less likely to be willing to part with it, which would have reduced their representation in this study as well," Marcus added.The study was also "open-label," meaning participants and researchers knew which group they were in. This can introduce bias, as expectations about caffeine’s effects may influence behavior or symptom reporting. The trial evaluated normal coffee consumption, not high-dose caffeine sources such as energy drinks or supplements. The authors cautioned that their findings should not be interpreted as evidence that all caffeine is beneficial."Individuals should not extrapolate these positive findings regarding caffeinated coffee to higher doses of caffeine or synthetic caffeinated products, such as energy drinks," Marcus said.Caffeinated energy drinks have been found to trigger AF in some cases, even among very young and healthy individuals.That morning cup of coffee could be the key to a happier day, new study suggests
Caffeine blocks brain receptors and
Increases Dopamine Activity
Published August 29, 2025
A recent study found that your morning cup of coffee really does make you happier – even if you're not a caffeine addict.The study involved researchers from the University of Warwick in the United Kingdom and Germany's Bielefeld University. It was recently published in the journal Scientific Reports.The study followed 200 young adults over four weeks and measured their moods.Participants received prompts on their phones seven times a day as part of the study. They were asked to record how they currently felt and how recently they had consumed caffeine.Caffeine drinkers recorded better moods after a cup of coffee or tea in the first two and a half hours of waking up, compared with later in the day.The mood boosts were linked to caffeine consumption, with researchers finding that the positive emotions included enthusiasm and happiness.Psychology professor Anu Realo of the University of Warwick said the positive effects happen after caffeine blocks adenosine receptors in the brain."[This] can increase dopamine activity in key brain regions – an effect that studies have linked to improved mood and greater alertness," Realo said. She also noted that an important factor may be related to caffeine dependence."Even people with moderate caffeine consumption can experience mild withdrawal symptoms that disappear with the first cup of coffee or tea in the morning," she added.Researchers made another surprising discovery. Some of the anxiety-prone respondents didn't always experience worrying thoughts after drinking coffee — and mood-boosting effects were observed across the board."We were somewhat surprised to find no differences between individuals with varying levels of caffeine consumption or differing degrees of depressive symptoms, anxiety or sleep problems," Bielefeld University research associate Justin Hachenberger said."The links between caffeine intake and positive or negative emotions were fairly consistent across all groups."Carrie Lupoli, a Connecticut-based nutritionist and health coach, told Fox News Digital that drinking coffee is deeply tied to behavior and routines. "A morning cup of coffee engages all the senses and signals to the brain that the day is beginning." the expert said."That sensory experience, combined with our body’s natural rise in cortisol and willpower in the morning, creates a powerful association with feeling energized and even happier."Lupoli said that even after experimenting with decaffeinated coffee, she observed the same positive effects on herself."The ritual alone still brings that same sense of calm and fresh-start energy," she said. "So yes, coffee may make us happier, but it's often as much about the habit and mindset as it is about the caffeine."Jenelle Kim, a doctor of Chinese medicine, told Fox News Digital that rituals like drinking coffee "set the tone for our day."The California-based medical expert did caution against too much caffeine, noting that it can spike cortisol and blood sugar levels that increase fatigue."In Eastern medicine, caffeine disperses qi, giving us energy, but too [much] forces the body to dip into reserves and depletes vitality," she said."In balance, one or two mindful cups can boost happiness and focus. Beyond that, it shifts from supportive to depleting."