For lots of guys, the promise of illegal anabolic steroids—that theyll help build muscle mass and strength—is just too strong.

Worldwide, about 1 in 15 men have tried steroids at some point in their lives, a 2014 analysis of 271 studies concluded. And that number refers to men overall: The percentage for recreational athletes, including those who lift, is about three times higher.

While steroid use is pretty common, it’s not harmless. We've known for years that steroids can be dangerous, leading to issues like kidney failure, liver damage, and an enlarged heart, as well as shrinking testicles and lowered sperm counts. Now, a new study adds further evidence that the illegal muscle builders may have serious consequences: Taking steroids could set the stage for a heart attack, new research presented at the Brazilian Congress of Cardiology suggests.

In the study, researchers recruited 51 seemingly healthy men with an average age of 29 years old. Some lifted and took steroids, some lifted and didn’t take the drugs, and others were sedentary and did not take steroids. All took urine tests to make sure they reported their steroid use accurately, as well a CT scan to check out their arteries.

The results? About 1 in 4 lifters who took steroids had signs of atherosclerosis, or plaque buildup, in the arteries leading to their hearts. In comparison, none of the sedentary men or the lifters who did not use steroids showed buildup.

Plaque buildup is a big problem. If a piece of it breaks off and gets stuck in your bloodstream, it can block blood flow to your heart. And that can cause a heart attack, according to the American Heart Association.

The steroid users also had lower levels of HDL cholesterol, or the “good” kind, the researchers found. Having enough HDL cholesterol is important because it helps carry LDL, or the “bad” kind, out of your body before it can build up in your arteries.

It’s possible that anabolic steroids spark the activity of a certain enzyme in your liver that’s responsible for increasing LDL, or “bad” cholesterol, while tamping down the good kind, says study author Francis Ribeiro de Souza, Ph.D. (c), of the Heart Institute of the Medicine School of the University of São Paulo. The result is an imbalance of your good and bad cholesterol, which can lead to plaque formation.

Scary part is, some studies have suggested that the heart issues, like the hypertension and enlarged heart, may be irreversible, too, says Ribeiro de Souza.

Larger studies are necessary to confirm the link between steroids and plaque buildup, but the results do seem to suggest that using the drugs can put even young, healthy men at risk for heart disease, he says.

The best—and incredibly obvious—way to protect your heart, then, is to avoid taking anabolic steroids

If you’ve taken them in the past? Then it’s super important you come clean to your doctor about your history. He or she may recommend additional testing to monitor your heart for any possible problems, Ribeiro de Souza says.