CELAYA, Mexico — Positive drug tests for five standout members of Mexico’s national soccer team have forced Mexican officials to acknowledge a problem that goes far beyond sports: Much of Mexico’s beef is so tainted with the steroid clenbuterol that it sickens hundreds of people each year.

Use of the steroid is illegal. But it has found a niche among ranchers, who marvel at the way it helps cattle build muscle mass before going to the slaughterhouse. The beef is pink and largely free of layers of fat, winning over unwitting consumers.

Ranchers call the powdery substance “miracle salts.” A few call it “cattle cocaine.”

Whatever name is used, the substance has unpleasant side effects for human beings. Last year, 297 people felt sick enough after eating tainted meat to visit hospital emergency rooms. Many more just endured the symptoms.

“It happened to me,” said Raul Martinez, a third-generation butcher in this dairy and cattle region of central Mexico. “When I fell ill, my heart started to race, and I got the shakes.”

The use of clenbuterol and the subject of steroid-tainted meat surged into headlines in Mexico last week when Mexico’s soccer federation announced the positive tests for the five players.

Team leaders asserted the result was due to eating tainted meat, and many agreed, including Mexican President Felipe Calderon.

“I believe it’s a matter of tainted food,” Calderon said during a visit to California over the weekend. “Indeed, many (ranchers) put who-knows-what kind of substances so that their cattle weigh a few kilos more.”