New research from the University of California, Riverside has shown that America’s most widely consumed oil – Soybean oil – can affect neurological conditions such as anxiety, depression, autism, and Alzheimer’s disease. Published in Endocrinology, the work builds upon previous studies that have identified a number of health risks associated with the oil, such as obesity and diabetes.

Soybean oil is by far the most widely produced and consumed edible oil in the USA according to the U.S. Department of Agriculture. It’s used to feed livestock and fry fast food, as well as being added to packaged foods.

In 2015, the team had modelled the effects of soybean oil in mice and showed that it can induce obesity, diabetes, fatty liver, and insulin resistance. In 2017, they showed that if soybean oil is engineered to be low in linoleic acid, it induces less obesity and insulin resistance. Now, the researchers have found that soybean oil can affect the hypothalamus where several critical processes take place, such as body temperature regulation, body weight management via metabolism, stress response, reproduction and physical growth.

The team compared mice fed three different diets high in fat: soybean oil, soybean oil modified to be low in linoleic acid, and coconut oil.

Several genes that didn’t function correctly were discovered through RNA-seq analysis. The gene encoding oxytocin, the “love” hormone, was found to be affected and resulted in decreased levels of oxytocin in the hypothalamus.

Around 100 other genes were found to be affected, and the team believe that they could possibly play a role in proper brain function, energy metabolism, and diseases such as Parkinson’s disease or autism. The team have yet to isolate the chemical that is responsible for the changes. It’s not linoleic acid though, as the modified soybean oil also produced the same effects as the unmodified version.

However, no proof has identified soybean oil as the cause of these diseases so far.

They team only used soybean oil for the investigation and no other soy products or vegetable oils. Only male mice were used, and since the oxytocin gene was found to be implicated, studies with female mice could be of importance as oxytocin is important for maternal health and mother-child bonding. Also, findings determined from mice doesn’t necessarily mean the same thing for humans.

More research is needed to identify the exact cause of these negative effects, which could help in designing healthier dietary oils and reduce the consumption of soybean oil in the future.