New research suggests that drinking coffee may increase cardiovascular risk in young adults, HealthDay reported.

Italian researchers found that heavy coffee drinkers had a four-fold increased cardiovascular risk (mainly heart attacks) while moderate drinkers tripled their risk. This, however, only applies to young people who've already got high blood pressure.

"There is controversy surrounding the long term cardiovascular and metabolic effects of coffee consumption in patients with hypertension," researcher Dr. Lucio Mos said in a statement. "Our study was designed to evaluate whether coffee drinking had an effect on the risk of cardiovascular events, and if the association was mediated by effects on blood pressure and glucose metabolism."

For the 12-year study, researchers collected and analyzed data from more than 1,200 non-diabetic patients aged 18 to 45 years old who had untreated stage 1 hypertension, Talk Radio News reported. Coffee consumption was categorized by the number of caffeine-containing cups per day: non-drinkers (0), moderate (1-3) and heavy drinkers (4 or more).

Among the participants, 26.3 percent were abstainers, 62.7 percent were moderate and 10 were heavy coffee drinkers. Coffee drinkers were older and had a higher body mass index than abstainers.

Researchers found a linear relationship between coffee use and risk of hypertension needing treatment. The association reached statistical significance for heavy drinkers. As type 2 diabetes often develops in hypertensive patients at a later stage, the study examined the long term effect of coffee drinking on the risk of developing prediabetes. A linear relationship was found, with a 100 percent increased risk of prediabetes in the heavy coffee drinkers.

"Our study shows that coffee use is linearly associated with increased risk of cardiovascular events in young adults with mild hypertension," Mos said. "This relationship seems to be at least partially mediated by the long term effect of coffee on blood pressure and glucose metabolism. These patients should be aware that coffee consumption may increase their risk of developing more severe hypertension and diabetes in later life and should keep consumption to a minimum."

The findings were presented at the European Society of Cardiology Congress on Saturday.