Researchers from the National Institutes of Health and University of North Carolina found that vegetable oil diets that help lower cholesterol levels do not reduce chances of having heart disease.
Doctors and dietitians have said for many years that vegetable oils rich in linoleic acids (a type of omega 6 polyunsaturated fat) such as soybean, canola and corn oils, are better for people’s health than animal fat, because those oils contain polyunsaturated fatty acids, which is good for the heart because they help lower cholesterol levels. In addition to that, health experts encourage people to replace saturated fats with small amounts of other, healthier fats, including oils rich in linoleic acid.Researchers from the National Institutes of Health and University of North Carolina found that vegetable oil diets that help lower cholesterol levels do not reduce chances of having heart disease. Photo credit: Kidney Buzz
But since the speculations of these oils not helping reduce the risk of heart diseases, researchers, led by Dr. Christopher Ramsden, from the National Institutes of Health and University of North Carolina decided to analyze previous studies because no randomized controlled trial had ever shown that replacing saturated fat with linoleic acid significantly reduced coronary heart disease or death.
The researchers analyzed the data from a large diet and cholesterol study from the 1960s and 70s, The Minnesota Coronary Experiment, which included 9,423 participants who lived in state mental hospitals and nursing homes. The study compared a control group who ate a diet high in saturated fat with a group whose diet included linoleic-rich corn oil instead.
The cholesterol of those who had a vegetable-oil diet lowered its levels but it did not improve heart disease rates or overall survival. It was actually found these people experienced a higher risk of death.
“In fact, participants who had greater reductions in cholesterol had higher, rather than lower, risk of death,” Dr. Ramsden said.
The researchers also examined other studies, unpublished data from a similar trial, the Sydney Diet Heart Study. They found that, after analyzing the data, the risk of death from coronary heart disease was higher among the people who had switched to safflower oil in place of saturated fat. Therefore, they could not find evidence of any reduction in death from coronary heart disease or other causes, even though the vegetable oil diets did lower cholesterol levels.
The Minnesota study was conducted 45 years ago, which is a concern, due to the fact that it was based on menus in an institution setting in the 60’s and the 70’s, and is most likely different from what we eat nowadays, according to what Dr. Clyde Yancy, chief of cardiology at Northwestern Medicine, told CBS News. He also says the study needs to be taken with a measured approach.
“We have not yet been able to identify a single variable in anyone’s diet that uniquely contributed to anyone’s heart disease or prevents it,” Yancy also added.