Why scientists say most adults can drink up to 5 cups of coffee per day
Three to five cups of black coffee per day is safe for most adults, but stronger energy drinks could harm cardiovascular health, according to a scientific statement published by the American Heart Association.
The best part of waking up could help lower the risk of cardiovascular disease, recent science suggests.
Between three and five 8-ounce cups of regular coffee, or 400 mg of caffeine, can safely be consumed each day by the average adult, according to a scientific statement published this month by the American Heart Association (AHA), which broadly summarized a collection of large cohort studies and smaller randomized controlled trials.
This declaration isn’t necessarily new and is consistent with guidelines in the U.S. and Europe, Northeastern experts said.
While studies on caffeine and coffee over the years report the benefits and warn about the harms, this statement offers an official viewpoint from the AHA to promote awareness of cardiovascular disease and to help develop guidelines, while highlighting what still needs to be studied, like caffeine in energy drinks.
It’s “really a myth-correction more than a new discovery,” said Stephen Wood, associate clinical professor in Northeastern University’s Bouvé College of Health Sciences.
“A lot of patients have been told for decades to cut caffeine for heart health, full stop, and this statement is a useful reminder that coffee drinking was probably never the villain we made it out to be,” he said. A handful of cups of coffee has actually been associated with a lower risk of coronary heart disease, stroke, heart failure, hypertension, atrial fibrillation or type 2 diabetes, according to the AHA statement.
“The actual villain, if there is one, is concentrated caffeine in energy drinks,” Wood said.
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The AHA’s statement noted that people should be cautious about consuming energy drinks. Energy drinks contain three to four times as much caffeine as a cup of coffee and should be avoided, the statement said.
But before you fire up your coffee machine, consider your own health status and the way in which you enjoy a cup of joe, Wood said. Northeastern experts also spoke to Northeastern Global News about some other things to consider before upping your caffeine intake.
Is there such a thing as too much coffee?
“It’s not a bright red line where cup #6 flips a switch and hurts you, but it’s a reasonable ceiling for most healthy adults,” he said. “Where it gets interesting is the shape of the curve.”
For blood pressure, for instance, the heart association statement points to studies that show an increased risk of hypertension when drinking one to three cups of coffee per day, but a decreasing trend with more coffee consumed. One observational study showed a greater risk of heart failure with five or more cups per day, but a batch of other studies found no risk or moderately lower risk with this level of consumption.
“So, the real answer for ‘too much’ is probably somewhere in that four- to five-cup range for most people, and less for people with certain conditions or genetics,” he said, like high blood pressure or anxiety.
How does caffeine interact with the body and how can it help lower these risks?
Many factors play a role in caffeine’s effect on the body, including dosage, form, genetics, weight and what foods may have been ingested with it.
The AHA’s statement notes that caffeine metabolizes at different rates in a person’s body, depending on if they’ve been previously exposed or their genetics.
Caffeine works to block a type of signaling protein, said Deborah Gater, assistant professor of chemistry on Northeastern University’s London campus. These proteins sit outside of a cell’s outer membrane, transmitting signals to the other side.
“One thing that makes these systems so complex is that the body can use the same signalling molecule – adenosine – to have different effects in different parts of the body, depending on what other proteins … are present in a particular cell,” she said.
Caffeine binds to a specific receptor expressed in the brain, blood vessels and immune cells, Gater noted.
This blockage effect “ramps up ‘fight or flight’ nervous system activity that gives you the jittery, alert feeling,” Wood said.
“On its own, that sounds like it should stress the cardiovascular system, and [in the] short term, it does raise heart rate and blood pressure a bit,” he said.
But caffeine, as an ingredient in coffee, does not act alone.
“It is a complex chemical cocktail with … compounds that appear to have antioxidant and anti-inflammatory effects,” Wood said. “Over the long run, in [studies that look at large groups] that combination seems to net out favorably for risk of heart disease, heart failure, and stroke,” he said.
Does it matter what form the caffeine comes in?
It does, experts said.
“This isn’t a blanket ‘caffeine is good for your heart’ finding. It’s specifically about caffeine from black coffee,” Wood said. “Concentrated caffeine hits from other sources are a different risk profile entirely.”
The caffeine consumed through a black coffee and a Starbucks Caramel Frappuccino is not the same. The AHA statement points out that added sugar, flavored syrup and creamers could cancel out any benefits to coffee.
The statement also notes that studies on energy drinks suggest cardiovascular harm, with the ingredient taurine, an amino acid that occurs naturally in the body, causing a faster uptake of caffeine in the body than the rate for coffee or tea.
Gater said she appreciated that the statement acknowledged more needs to be studied with energy drinks. She has seen firsthand how popular these drinks can be with some of her students.
“Caffeine is a natural product that humans have consumed in a variety of plant-extract forms … for hundreds or thousands of years. Our consumption of caffeine separate from those extracts – in supplements and energy drinks – is a lot more recent,” she said.
What should people ask their doctor before drinking up to five cups of coffee per day?
Certain conditions may preclude someone from partaking in this ritual.
“If someone already has [irregular heartbeat], uncontrolled high blood pressure, anxiety disorders, [gastrointestinal] issues like reflux, or is pregnant, this isn’t a green light to start drinking more coffee,” Wood said.
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Overall, the statement emphasizes that more research needs to be done to understand the individual’s response to caffeine, the effects of caffeine separate from its liquid vehicle and if non-coffee drinkers can benefit.
Wood also noted that the AHA did not list caffeine or coffee in its 2026 dietary guidelines for heart health, meaning it did not flat-out encourage caffeine intake for this purpose because it lacked enough data to offer recommendations.
