Scientists have discovered a possible explanation as to how soybean oil, the most widely used cooking oil in the United States, leads to obesity just in time for the Trump administration’s new guidance on nutrition standards expected before the end of the year.
Soybean oil and other seed oils have been a target of Health and Human Services Secretary Robert F. Kennedy Jr., and the Make America Healthy Again movement, which focuses on diet as the source of chronic diseases like obesity and heart disease, but the exact mechanism of how soybean oil contributes to obesity has not been well understood.
But researchers at University of California Riverside in a study published earlier this week conducted an experiment that might explain how the breakdown of soybean oil in the body leads to increased fat storage and inflammation.
Researchers fed a high-fat diet rich in soybean oil to groups of mice, most of which gained significant weight. But a different group of genetically engineered mice did not gain weight due to a slight variation in a particular liver protein that influences genes linked to fat metabolism.
The protein appears to have a sizable effect on how linoleic acid, a major component of soybean oil, is processed in the body. Linoleic acid is converted into oxylipins, which are associated with inflammation and fat accumulation, according to the research.
Variations in the production of these liver proteins, along with differences in age, sex, and genetics could explain why some people are more susceptible to the effects of soybean oil than others.
“This may be the first step toward understanding why some people gain weight more easily than others on a diet high in soybean oil,” said Sonia Deol, a UCR biomedical scientist and one of the co-authors of the study.
Holistic health critics have criticized soybeans for more than a decade, but they have also become a political joke among conservatives. In the mid-2010s, the derisive term “soyboy” became a popular term among right-wingers online to refer to men who do not conform to traditional forms of masculinity or are “soft.”
U.S. consumption of soybean oil has increased fivefold over the past century, from about 2% of calories in the early 1900s to nearly 10% as of 2011.
Soybean oil has a market share of 24% worldwide for total vegetable oil consumption, but it accounts for nearly 75% of the total vegetable oil intake in the U.S., according to the National Commodity and Derivatives Exchange.
Although soybean oil is a main ingredient in most ultra-processed foods, it is also used in home cooking and is often found in vegetable oil blends.
“Soybean oil isn’t inherently evil,” Deol said. “But the quantities in which we consume it is triggering pathways our bodies didn’t evolve to handle.”
The new findings explaining the link between soybean oil and obesity come as Kennedy and Agriculture Secretary Brooke Rollins are poised to release the updated Dietary Guidelines for Americans.
The DGA is a policy document produced every five years that governs the nutrition standard for federally funded food programs including food stamps, the federal school lunch program, and military diets.
The guidelines are the primary vehicle by which Kennedy will be able to implement his goal of reducing seed oil consumption and lowering ultra-processed food intake.