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Reanalyzing the Health Effects of Plant and Animal Fats

Mattie Hagedorn

If you’re trying to eat healthier, you might find yourself switching out butter for olive oil. Many believe that plant-based fats, rich in linoelic acid, are healthier than saturated fats like lard or butter. Saturated fats raise your cholesterol, and that supposedly raises your risk of dying from a heart attack. 

But a new analysis of data from the Minnesota Coronary Experiment is challenging that belief. The study found that the kind of fat a person ate had no real effect on coronary mortality. In fact, it found that people with lower cholesterol were slightly more likely to die from heart problems. 

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"The benefit of replacing saturated fat with vegetable oil, rich in linoleic acid, has been test in randomized control trials which are the golden standard. But none of them have actually show that it has a benefit on coronary heart disease mortality or overall mortality," say Dr. Daisy Zamora, one of the authors on the study. 

Zamora says that earlier studies have focused on heart health, but most have failed to look at the effects of fat consumption on coronary mortality rates. She believes the overall goal of keeping your heart healthy is to avoid a death caused by heart issues, and that the emphasis on things like cholesterol has been a bit counterproductive. 

"I think that the emphasis on intermediate biomarkers, such as cholesterol, has perhaps been a little misguided in that by itself, it really doesn't mean anything," she says. "So lowering cholesterol was really only important because it was thought to lower heart disease and prevent death. But if that's not the case, then there really isn't a reason to want to focus on it." 

Naturally, the findings have been controversial.

Some have criticized the study for being irrelevant and claim the "reanalysis" fails to add anything new to our understanding of linoleic acid and saturated fats. But Zamora has dismissed many of these concerns as being reactionary. "I would really like to let the data speak for itself," she says. 

"The reason they're relevant today is that as a population our intakes of linoleic acid are a lot higher than they would be from unprocessed diets. So up to about 100 years ago, the average intake for an American was about 2-3% energy from linoleic acid. Now the average is about 7%," says Zamora. 

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Joy Powers joined WUWM January 2016 as producer for Lake Effect. Most recently, she was a director and producer for The Afternoon Shift, on WBEZ-fm, Chicago Public Radio.