Research at the University of California-Riverside has yielded a surprise:
A diet high in soybean oil causes more obesity and diabetes than a diet high in fructose, a sugar commonly found in soda and processed foods, according to a just published paper by scientists at the University of California, Riverside.
The scientists fed male mice a series of four diets that contained 40 percent fat, similar to what Americans currently consume. In one diet the researchers used coconut oil, which consists primarily of saturated fat. In the second diet about half of the coconut oil was replaced with soybean oil, which contains primarily polyunsaturated fats and is a main ingredient in vegetable oil. That diet corresponded with roughly the amount of soybean oil Americans currently consume.
The other two diets had added fructose, comparable to the amount consumed by many Americans. All four diets contained the same number of calories and there was no significant difference in the amount of food eaten by the mice on the diets. Thus, the researchers were able to study the effects of the different oils and fructose in the context of a constant caloric intake.
Compared to mice on the high coconut oil diet, mice on the high soybean oil diet showed increased weight gain, larger fat deposits, a fatty liver with signs of injury, diabetes and insulin resistance, all of which are part of the Metabolic Syndrome. Fructose in the diet had less severe metabolic effects than soybean oil although it did cause more negative effects in the kidney and a marked increase in prolapsed rectums, a symptom of inflammatory bowel disease (IBD), which like obesity is on the rise.
So, if you’re a mouse, don’t ingest soybean oil. Mouse models are not necessarily good proxies for humans, but it’s something worth worrying about. Where does soybean oil show up in food products?
… is found in processed foods, margarines, salad dressings and snack foods. Soybean oil now accounts for 60 percent of edible oil consumed in the United States. That increase in soybean oil consumption mirrors the rise in obesity rates in the United States in recent decades.
And …
The researchers cautioned that they didn’t study the impacts of the diets on cardiovascular diseases and note in the paper that the consumption of vegetable oils could be beneficial for cardiac health, even if it also induces obesity and diabetes.
I’m still considering avoiding soybean oil, and it’s definitely an issue to keep on the radar for the future.
