Why Switching to Vegetable Oil Won’t Help You Live Longer

Reducing animal fat may not reduce the risk of death from heart ailments
Why Switching to Vegetable Oil Won't Help You Live Longer

By: Steven Nissen, MD

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You may have spent years carefully avoiding foods such as beef, butter and cheese to help ensure a healthy heart and a long life. But new research questions the advice to cut back on eating animal-derived saturated fats to reduce artery-clogging cholesterol.

The study finds no association between switching from saturated fat to vegetable oil and a longer life or a reduced risk of heart attack or stroke.

The findings, published recently in the British Medical Journal, suggest that reducing the amount of saturated fat in your diet isn’t enough to reduce your risk of death from heart disease or stroke.

A re-analysis

The new report analyzed 40-year-old data from the Minnesota Coronary Experiment, which investigated whether substituting corn oil for saturated fats would reduce heart disease risk by lowering blood cholesterol levels.

In that study, researchers divided more than 9,000 people into two groups.  One group substituted saturated fats for unsaturated fats — vegetable fats in the form of corn oil and corn-oil margarine. The second group continued their usual daily saturated fat eating habits.

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More recently, researchers from the National Institutes of Health and University of North Carolina obtained data from 2,355 of these participants — information that apparently had not been included in the original analysis.

They concluded that the diet rich in vegetable oil did lower cholesterol levels slightly over the five-year study period, compared to the saturated fat group.

But, significantly, the researchers also found no change in the risk of death from heart disease, stroke or other heart-related ailments.

Old advice

The standard medical advice for decades has been to switch from saturated fats to vegetable oils – based in large part on this study.  Unfortunately, the advice probably wasn’t based on good science.

Using more modern and sophisticated scientific methods, the recent re-analysis of the study no longer supports the position that saturated fat and cholesterol in the diet are the main drivers of heart disease.

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There is a lot we still don’t know about certain types of fat in the diet. But evidence is accumulating that your body’s cholesterol levels are strongly influenced by your genes, rather than your diet. This is why statins can be a powerful ally in reducing your level of LDL, or “bad,” cholesterol.

Even our own U.S. Dietary Guidelines, which tend to be very conservative, is now beginning to recognize that a lot of that old advice about cholesterol and eggs was not on target.

Good fats, bad fats

One fat that has solid science behind it is olive oil. A Spanish study recently showed that large quantities of olive oil reduced the risk of developing heart disease in the study’s participants. And the diet that has consistently shown benefit in randomized control studies is the Mediterranean diet. It’s been shown to reduce the risk of heart attack and stroke as well as lower LDL, or bad, cholesterol.

Also, scientists universally accept that trans fats — found in many fast foods, bakery products, and margarines — increase the risk of cardiovascular disease. Trans fats are man-made substances created by bubbling hydrogen gas through healthy oils.  They’re typically listed on food packages as trans fat or partially hydrogenated oil. In 2013, the U.S. Food and Drug Administration made a preliminary determination that partially hydrogenated oils are no longer generally recognized as safe in human food.

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