A new study says that drinking four cups of coffee or more a day could be linked to an earlier death.

The Mayo Clinic study, which included about 40,000 people and encompassed 16 years, showed that 28 cups of coffee per week was linked to a 21% higher mortality rate in men and women of all ages, and a 50% higher mortality rate in people under 55 years old.

“We’re not saying that coffee is the cause of death; we just noticed coffee is associated with increased risk of death,” study co-author Dr. Carl Lavie said. He added that drinking coffee every day in smaller amounts didn’t show effects during the study either positively or negatively.

However, a study by the National Cancer Institute last year showed that people who drank 3 or more cups of coffee per day were 10% less likely to die than those who don’t drink it, and it they were also less likely to die from heart disease, respiratory disease, stroke, injuries and accidents, diabetes and infections.

“I do think it would be reasonable to use some caution at doses of four cups a day and above, and realize that a cup is probably a 6- to 8-oz. cup and not the grandes and supergrandes that are now available,” Lavie said. “It appears to be safe in small to moderate amounts, and there may even be some benefits.”

Potential factors in the coffee/health risk study are the amount of caffeine it contains and the possibility of increased blood pressure.

“The exact mechanism between coffee and mortality still needs clarification. Coffee is high in caffeine, which has the potential to stimulate the release of epinephrine, inhibit insulin activity, and increase blood pressure,” said Xuemei Sui, a co-author on the study.