Butter: The Good, The Bad, The Ugly

A University of North Carolina School of Medicine study showed conflicting beliefs and facts about linoleum acid and butter substitutes.


There's butter spray, butter spread and vegetable oil spread that taste like butter. Face it; there is something about the flavor and aroma of butter that has captured our taste buds and here's some good news. It might not be as bad as once thought. New research at the University of North Carolina School of Medicine shows that replacing butter with vegetable oil does not decrease your heart disease risk.

Findings reported in the British Medical Journal showed that consuming vegetable oil containing linoleic acid could actually be worse than just using its butter counterpart. Linoleic acid can be found in foods such as safflower oil, soybean oil, sunflower oil and cottonseed oil.

Evidence for this finding also comes from a variety of sources, including a Minnesota trial conducted 50 years ago and an analysis of published data from similar trials.

The analysis found that linoleic acid rich foods did not reduce heart disease. The dietary intervention did reduce cholesterol levels in participants. In the Minnesota study, participants who had a decrease in cholesterol levels actually had a higher mortality risk.

“Altogether, this research leads us to conclude that incomplete publication of important data has contributed to the overestimation of benefits and the underestimation of potential risks of replacing saturated fat with vegetable oils rich in linoleic acid," research author Daisy Zamora, PhD, a researcher in the Department of Psychiatry at the UNC School of Medicine, said.

This dietary myth dates back to the 1960s when studies showed that the dietary switch lowered blood cholesterol levels. This belief was reaffirmed in 2009 when the American Heart Association reaffirmed its views that dietary saturated fats were probably not beneficial to the heart.

Trials have never shown that a linoleic acid dietary intervention reduces heart attacks or deaths related to heart disease.

Between 1968 and 1973, the Minnesota Coronary Experiment looked at 9,423 participants from six states' mental hospitals and one nursing home. The results of this research concluded that the dietary switch from corn oil to butter lowered cholesterol levels but did decrease the risk of heart disease, heart attack deaths or overall mortality. In fact, those who were on the linoleic acid dietary regiment were actually 15 percent more likely to die than their butter eating counterparts.

In 2013, Ramadan Zamora and colleagues recovered data from the Sydney Diet Heart Study. In this study, the researchers found higher cases for heart disease and mortality among the participants who received the linoleic acid dietary intervention when compared to the control.

“There were some differences among these studies, but on the whole they didn’t really disagree,” Zamora said.

Researchers feel linoleic acid reduces blood cholesterol levels, however, it may worsen a person's risk of heart disease. The reason for this is a topic of heated discussion. Some feel these oils can cause inflammation in the body—a known risk factor for heart disease—or the oils promote atherosclerosis when they are chemically modified through oxidation.

Nevertheless, years of research continues to help us on the path to battling heart disease.