Some people drink diet soda hoping it’s a slightly healthier alternative to regular soda. Unfortunately for diet soda drinkers, a new study has some bad news.

New research presented Wednesday at the International Stroke Conference has linked diet soda with higher risks for strokes and heart attacks.

Doctors are still uncertain why this is, and are allowing for the possibility that people who drink diet soda on a daily basis may have unhealthier lifestyles than those who drink it sparingly, if at all. However, in the research conducted by the Northern Manhattan study, which looked at 2,500 adults over a nine year period, daily diet soda drinkers had a 48 percent higher risk than non-soda drinkers, even after taking into account smoking, diabetes, weight and other variables among the test-subjects.

Over the nine years the study was conducted, there were 559 strokes or heart attacks among those studied, with 338 of the cases fatal. Participants in the study, which spanned from 1993 until 2001, were tapped for the study through random phone calls. Half of those studied were Hispanic, while a quarter were black, making the study one of the few to look at minorities.

Dr. Steven Greenburg, vice chairman of the conference and a neurologist with Harvard Medical School, said that the findings should be a “wake-up call to pay attention to diet sodas.” The lead researcher for the study, Hannah Gardener from the University of Miami, urged prudence in looking at the study’s results.

“This needs to be viewed as a preliminary study…it’s too preliminary to suggest any dietary advice,” Gardener said. She acknowledged more major studies are needed.

Earlier studies have found ties between soda—both the regular and diet variety—and a greater risk of diabetes and weight-related issues. A study published in the Fall 2010 edition of the American Medical Journal also found a connection between soda and gout in women.