For once, the University of Pittsburgh Medical Center might be happy to be ranked near the bottom of a list of America's top hospitals.

An analysis conducted by the Center for Science in the Public Interest, a Washington, D.C. consumer advocacy group, showed that the french fries served in the cafeterias of many of the country's best hospitals were loaded with unhealthy trans fat.

"Trans fat is such a potent promoter of heart disease that hospitals, of all places, should not be using it," said Michael F. Jacobson, the center's executive director.

Patients and their families might not be harmed very much because they don't stay in the hospital for long, "but the doctors and nurses, they may eat there every day," he added

For the project, medical students and other workers at 14 of the 16 top hospitals in an annual ranking by U.S. News and World Report sent two orders of fries from their primary cafeterias to the center in November. The center then sent the food for testing at an independent lab.

Each submission was standardized to 6 ounces, or the size of a large order of fries at McDonald's.

Two of the leading medical centers, the Cleveland Clinic and Johns Hopkins, did not make the center's list because "they don't sell any fried foods at all," Dr. Jacobson said. Massachusetts General Hospital and the Mayo Clinic were not included because they had changed their frying practices after the testing.

Trans fat is formed when vegetable oil is hardened by hydrogenation and it's found in fried foods, commercial baked goods and other processed foods. It is used to extend shelf life and preserve flavor, but it can raise LDL, or so-called "bad" cholesterol levels, and lower HDL, or "good" cholesterol.

Dietary guidelines suggest limiting trans fat intake to less than 2 grams per day, Dr. Jacobson said.

A 6-ounce serving of fries from UPMC contained 1.8 grams, the analysis found. "That means you've shot it for the day," he said.

Thirteen hospitals, including several pediatric hospitals had worse results. The University of Pennsylvania's hospital cafeteria topped the center's rankings with 5.3 grams of trans fat in its fries. Children's Hospital of Philadelphia, however, fared the best with 1.2 grams.

By comparison, McDonald's reports that there are 8 grams of fat in an order of its large fries. The National Institutes of Health's fries tested at 0.2, and the U.S. Food and Drug Administration came in at 0.1, the analysis showed.

Fries made from scratch and cooked in soybean oil by center staffers contained a negligible amount of trans fat.

The variation in hospital cafeterias might be due to how the potatoes are processed by the manufacturer, Dr. Jacobson said. Some fries are "par-fried" or partially fried and then frozen for shipping to the commercial kitchens.

Cafeteria workers finish the frying process. If they use partially hydrogenated oil, the trans fat content probably goes up. If they use liquid vegetable oil, the content is lower, he explained.

Trans fat labeling regulations went into effect for packaged food on Jan. 1.

Restaurants do not have that pressure, Dr. Jacobson said.

"People would be wise to avoid fried foods in any case, but especially if it's fried in partially hydrogenated oil," he advised.