Feel free to have that second cup of coffee.

Coffee’s health benefits – and detriments – have been in the news a lot recently, and there seems to be a lack of a clear answer. That indecision is what prompted researchers in Boston to study the amount of coffee that may have health benefits, and when precisely coffee stops giving them.

Focusing on the relationship between coffee and heart health, the group was led by Elizabeth Mostofsky, MPH, ScD, from the cardiovascular department of Beth Israel Deaconness Medical Center. Researchers found that coffee drinkers generally had an 11 percent lower risk of heart failure.

The team analyzed data from five previous studies – four conducted in Sweden and one in Finland. Within these studies, researchers analyzed the self-reported data from 140,220 participants. Of the participants in the five studies, 6,552 of these reports involved heart failure events.

Researchers found that the benefits of coffee had a J-shaped curve which meant coffee’s ability to help ward off heart issues increased the more cups of coffees the participants drank. That benefit stopped at around the fourth cup of European coffee or second cup of eight-ounce American coffee. Drinking more than five cups of coffee may do more harm than good, not researchers.

Researchers have unable to pinpoint the cause of the link between coffee and heart health, but they suggest that it may have to do with coffee’s effect on diabetes and high blood pressure. Both conditions are risk factors for heart failure, and coffee drinkers tend to have a lower risk of type 2 diabetes.

More recently, researchers have discovered that people who drink coffee tend to have higher blood pressure than their non-coffee drinking counterparts. But this may actually be beneficial as researchers hypothesize that the body may develop a tolerance to it, and can potentially prevent the elevated blood pressure that can lead to heart failure.

The study did not control for the preferred strengths of participants’ coffee, nor did it control for whether participants drank caffeinated or decaffeinated versions of the hot beverage.

The results of the study were published in Circulation: Heart Failure.