While current American Heart Association heart failure prevention guidelines warn against habitual coffee consumption, some studies propose a protective benefit, and still others find no association at all. Amidst this conflicting information, research from Beth Israel Deaconess Medical Center attempts to shift the conversation from a definitive yes or no, to a question of how much, the Science Daily reported Tuesday.

"Our results did show a possible benefit, but like with so many other things we consume, it really depends on how much coffee you drink," says lead author Elizabeth Mostofsky, MPH, ScD, a post-doctoral fellow in the cardiovascular epidemiological unit at BIDMC, according to the magazine. "And compared with no consumption, the strongest protection we observed was at about four European, or two eight-ounce American, servings of coffee per day."

The study published June 26 online in the journal Circulation: Heart Failure, found that these moderate coffee drinkers were at 11 percent lower risk of heart failure.

In a summary of the published literature, the authors found a "statistically significant J-shaped relationship" between habitual coffee consumption and heart failure, where protective benefits begin to increase with consumption maxing out at two eight-ounce American servings a day. Protection slowly decreases the more coffee is consumed until at five cups, there is no benefit and at more than five cups a day, there may be potential for harm.

It's unclear why moderate coffee consumption provides protection from heart failure, but the researchers say part of the answer may lie in the intersection between regular coffee drinking and two of the strongest risk factors for heart failure -- diabetes and elevated blood pressure, the Science Daily said.