We're looking at you, soybean oil!
According to the U.S. Department of Agriculture, soybean oil is by far the most widely produced and consumed edible oil in the United States. New UC Riverside research shows soybean oil not only leads to obesity and diabetes, but could also affect neurological conditions like autism, Alzheimer's disease, anxiety, and depression.
In all fairness, the study was conducted on male mice. Still, the conclusion is stern and alarming: "given its ubiquitous presence in the American diet, the observed effects of soybean oil on hypothalamic gene expression could have important public health ramifications."
The same UCR research team found in 2015 that soybean oil induces obesity, diabetes, insulin resistance, and fatty liver in mice. Then in a 2017 study, the same group learned that if soybean oil is engineered to be low in linoleic acid, it induces less obesity and insulin resistance.
In the study released this month, researchers found pronounced effects of the oil on the hypothalamus.
"The hypothalamus regulates body weight via your metabolism, maintains body temperature, is critical for reproduction and physical growth as well as your response to stress," -- Margarita Curras-Collazo, UCR associate professor of neuroscience and lead author on the study
The scientists discovered roughly 100 other genes affected by the soybean oil diet, including the one that produces oxytocin, the "happiness" hormone. In soybean oil-fed mice, levels of oxytocin in the hypothalamus went down.
"The dogma is that saturated fat is bad and unsaturated fat is good. Soybean oil is a polyunsaturated fat, but the idea that it's good for you is just not proven." -- Frances Sladek, UCR toxicologist and professor of cell biology
As a matter of fact, coconut oil -- which contains saturated fats and it was used as a control oil in the study -- produced very few genetic changes in the hypothalamus.
Further investigations are required to determine the exact compounds in soybean oil that are responsible for these negative effects. It is also worth mentioning that the findings only apply to soybean oil -- not to other soy products or to other vegetable oils.