MedWire News: Drinking two cups of coffee a day may significantly reduce risk for heart failure (HF), while anymore than that could significantly increase the risk, researchers say.
The findings are in contrast to current American HF guidelines, which state that coffee consumption may increase HF risk.
Murray Mittleman (Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA) and team observed that compared with no coffee consumption, drinking four Northern European servings of coffee a day, which is equivalent to two American coffee shop servings, was linked to an 11% lower risk for HF.
On the other hand, excessive coffee consumption, defined as 10 Northern European servings or five to six American coffee shop servings per day, was associated with no significant benefit in terms of HF risk, while drinking more than nine or ten Northern European servings per day was associated with a significantly increased risk for HF, at hazard ratios of 1.01 upwards.
The J-shaped relationship between coffee consumption and HF incidence did not vary by gender or history of myocardial infarction or diabetes, as reported in Circulation: Heart Failure.
"This is good news for coffee drinkers, of course, but it also may warrant changes to the current HF prevention guidelines, which suggest that coffee drinking may be risky for HF patients," commented lead study author Elizabeth Mostofsky, also of Beth Israel Deaconess Medical Center, in a press statement.
"It now appears that a couple of cups of coffee per day may actually help protect against HF."
Mittleman and team state that the mechanism underlying the association between coffee consumption and HF risk is unclear, but allude to previous evidence that suggests frequent coffee drinkers develop a tolerance to caffeine, which may put them at a reduced risk for developing hypertension.
Habitual coffee consumption has also been linked to a lower risk for developing Type 2 diabetes, they add.
The researchers did not account for brew strength in their study, but point out that coffee is typically weaker in the USA than in Europe.
They also did not differentiate between caffeinated and decaffeinated coffee, both types being included in the meta-analysis, but say that most of the coffee consumed in Sweden and Finland, where all the studies were conducted, is caffeinated.
"While there is a commonly held belief that regular coffee consumption may be dangerous to heart health, our research suggests that the opposite may be true," stressed Mittleman.
The meta-analysis comprised five prospective studies of coffee consumption and heart failure risk published between 2001 and 2011. The studies included 6522 HF events among 140,220 men and women in Sweden and Finland.
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