MedicalResearch.com Interview with: Frances M. Sladek, Ph.D. Professor of Cell Biology and Toxicologist Associate Director, UCR Stem Cell Center Department of Cell Biology and Neuroscience University of California Riverside, CA 92521-0314 Medical Research: What is the background for this study? What are the main findings? Dr. Sladek: In 2011 Blasbalg et al reported in the American Journal of Clinical Nutrition that the consumption of soybean oil was the component of the American diet that had changed the most since the early 1900s. It had in fact increased 1000-fold. Soybean oil is currently not only the main type of vegetable oil used in the U.S. but soybean meal is a major component of the diet of the animals such as cows and pigs, resulting in changes in the fatty acid composition of animal fat. Soybean oil is also increasingly being used worldwide: 40 million tons were produced in 2007 alone. In our previous study we found that a high fat diet containing comparable amounts of soybean oil to what Americans are currently consuming caused mice to become obese, diabetic and insulin resistant and to have large lipid droplets and hepatocyte ballooning in their livers. Others had found similar results and proposed that linoleic acid (an omega 6 polyunsaturated fat) that makes up >55% of the oil was responsible for the negative metabolic effects. DuPont recently generated a genetically modified  soybean oil  that had reduced levels of linoleic acid and hence less of a tendency to generate trans fats. This oil (called Plenish) came onto the market for the first time in 2014. The fatty acid composition of Plenish is similar to that of olive oil (low linoleic acid and high oleic acid), which is a major component of the healthy Mediterranean diet. The implication, therefore, is that Plenish is healthier than conventional soybean oil but that has not been formally proven. In the current study, we found that while a high fat diet containing Plenish also induced obesity, glucose intolerance and fatty liver, it did not induce insulin resistance as did the conventional soybean oil. It also induced somewhat less fat accumulation. Finally, we compared the diet enriched in soybean oil to an isocaloric diet that contained the same amount of total fat (40%kcal, Americans consume 34-37% fat) but with 90% of the fat from coconut oil. Those animals gained very little weight (13% versus 38% with the conventional soybean oil and 30% with the Plenish) and were not diabetic or insulin resistant. Their livers also had less fat than either of the two soybean oil diets and showed no signs of hepatocyte ballooning. Coconut oil has essentially no linoleic acid or other PUFAs. Our results, assuming humans respond in the same way as mice, suggest that people should avoid the consumption of too much soybean oil, either conventional or Plenish. They also show that coconut oil, which is made up of saturated fats (primarily medium chain triglycerides), is much healthier for you than soybean oil. Coconut oil has been noted previously for its beneficial health effects. (more…)