In Nature Scientific Reports journal on Monday, Oct. 2, researchers of UC Riverside published their findings on genetically modified (GM) soybean oil, which revealed the harmful effects this oil can have. This research is the first to compare Plenish, a GM soybean oil, with a conventional soybean oil on the long-term effects they have on a person’s metabolism.

Professor of Cell Biology and toxicologist Frances Sladek and Poonamjot Deol, Ph.D cell biologist, performed a series of experiments analyzing soybean oil. In the first experiment, Plenish and conventional soybean oil were compared to coconut oil to analyze which of these high-fat oils resulted in less weight gain when consumed over time. The results showed that all three oils caused a rise in cholesterol level, which contradicts the widely held belief that soybean oil reduces one’s cholesterol level.

In the following experiment, Plenish was compared to olive oil, because both are high in oleic acid, a fatty acid initially thought to help one lose weight and reduce blood pressure. Contrary to popular belief, the two oils caused higher weight gain compared to coconut oil and fatty liver. This came as a surprise due to the common belief that olive oil is healthy compared to other oils. Plenish’s effects were similar to olive oil as it enlarged the liver and created liver dysfunction.

The research comes at a time when soybean oil is increasingly popular, not only in the U.S., but internationally. A majority of restaurants use soybean oil, which can be labeled as vegetable oil, and as various soybean companies claim there are health benefits to soybean oil, consumers can be at a lost on what to believe.

When asked on what one should do when dealing with soybean oil, Sladek and Deol replied, “While it may not be possible to completely eliminate soybean oil from your diet, you should try to avoid it. Before buying an edible product, read the ingredients labels to be aware of what exactly you are consuming.” Likewise, after close examination, vegetable oil, for example, can actually be soybean oil with a different name. As a substitute, coconut oil would be advised because, as shown in the experiment, it had the least metabolic impact.

When the manufacturers of Plenish, Dupont, were asked their opinion on the study, they denied the harm found in their genetically modified oil. “Based on robust testing results, the Food and Drug Administration has labeled high-oleic soybean oil as ‘generally recognized as safe’ for use in food,” they wrote. “Additionally, the U.S. Department of Agriculture has given regulatory approval to plant Pioneer brand Plenish soybeans in the United States.”

Plenish’s statement seems to contradict Deol and Sladek’s findings, who stated in response, “We would advocate long-term testing of GM oils in addition to short-term toxicity tests, before making claims about their health benefits.” While the tests mentioned by Plenish may have said the soybean oil was safe for consumption, the researchers note those were short-term tests while the experiment itself analyzes the long-term effects.

In future studies, Sladek and Deol plan to continue testing soybean oils, focusing on how they affect intestinal health and the gut microbiome.