But the results of a massive study published last week in the Journal of the American Medical Association found little evidence to support the long-standing belief that low-fat diets help reduce the risk of heart disease.

"We're left not knowing any more than we did before," said Askew, who heads the Division of Nutrition at the University of Utah College of Health.

Experts hoped the long-term study would validate the idea that diets low in fat and high in fruits and vegetables would help people lower their risk of heart disease.

Nearly 50,000 women were split into two groups - a low-fat diet group and an unmodified diet group. Researchers followed up with each participant for an average of eight years.

When looking at incidence rates for coronary heart disease, stroke and cardiovascular disease, there were few differences between the low-fat diet group and the comparison group. The percentages were too close to show any significant advantage to a low-fat diet.

Nutritionists suspect several factors contributed to the study's results.

A major concern is that in recent years, experts have determined that not all fats are bad, Askew said. This study asked women to reduce all forms of fat in their daily diet.

"This good fat/bad fat concept hadn't really emerged at the time the study started," he said of the research, which began in 1992.

Nutrition researchers now suggest cutting down on saturated- and transfats, said Karen Segerson, director of the U.'s Cardiovascular Prevention Clinic.

"We still will continue to recommend that type of diet," she said, despite the findings from the JAMA study.

While the study indicates which diet does not appear to work, the results can't say which diets would work better, added Brent Muhlestein, director of cardiovascular research at LDS Hospital in Salt Lake City.

Some research suggests a diet low in saturated fats is beneficial to reduce the risk of heart disease, but Muhlestein said he is not comfortable telling people that is the definitive answer. There is only one thing Muhlestein can advise for certain.

"Being overweight is bad for your heart," he said.

He tells patients seeking to avoid another heart attack to strive for a well-balanced diet and an exercise regimen to help lose weight.

Segerson suggests people aim for eating more good fats such as omega-3 found in fish and plant sterols, which can be found in some salad dressings and margarines.

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Contact Greg Lavine at glavine@sltrib.com or 801-257-8620. Send comments to livingeditor@sltrib.com.