Coffee lovers can take heart: Up to 5 cups a day appears safe for most adults, experts say

Coffee drinkers may not have to feel guilty about reaching for another cup.

A new scientific statement from the American Heart Association says that consuming up to 400 milligrams of caffeine a day — the equivalent of about five 8-ounce cups of black coffee — is generally safe for most healthy adults and may even be linked to a lower risk of heart disease, stroke, heart failure and Type 2 diabetes. The findings were published Monday in the journal Circulation.

The review also found that the potential benefits are most consistently seen with plain black coffee rather than beverages loaded with sugar, flavored syrups or heavy cream.

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"For most healthy adults, up to about 400 milligrams of caffeine a day, which is roughly five cups of black coffee, appears safe," South Carolina-based registered dietitian Lauren Manaker, who was not involved in the research, told Fox News Digital.

"And the latest research links moderate coffee drinking with a lower risk of heart disease, stroke, heart failure and Type 2 diabetes. That's reassuring news for coffee lovers."

Manaker cautioned, however, that what people add to their coffee matters.

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"How you take your coffee makes a real difference," she said. "The benefits show up most clearly with plain black coffee. Once you start piling on sugar, flavored syrups and cream, you may be trading away some of the good you were hoping to get."

The American Heart Association also emphasized that coffee should not be lumped together with energy drinks, which often contain much higher doses of caffeine and other stimulants.

Higher amounts of caffeine — particularly from energy drinks and energy shots — have been associated with elevated blood pressure and irregular heart rhythms.

"Coffee and energy drinks are not the same thing, and we shouldn't treat them that way," Manaker said.

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"Energy drinks and shots can pack three to four times the caffeine of regular coffee, often with added ingredients, and higher doses have been linked to raised blood pressure and irregular heart rhythms. That's the source I'd steer people away from."

The researchers also noted that caffeine doesn't affect everyone equally. Factors including age, medications, genetics and how quickly the body metabolizes caffeine can all influence an individual's tolerance and risk.

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More research is still needed, particularly because much of the existing evidence is based on observational studies.

"There's no one-size-fits-all caffeine limit," Manaker said. "Your age, your medications, your genetics and how quickly your body clears caffeine all shape how you respond. What feels fine for your co-worker might leave you jittery or awake at 2 a.m."