Study Reveals Possible Link Between Soybean Oil And Neurological Conditions

You might not use soybean oil in the kitchen, but chances are you would've consumed something that's been cooked in it, especially since it is one of the most common cooking oils used not just in the United States, but around the world. To give you an idea of how much soybean oil is consumed, Healthline says a staggering 62 million tons of soybean oil was produced between 2018 and 2019. Per Food Insight, the edible fat is to prepare just about everything — from snacks to dressings, and in frozen foods and vegan meat options. 

There are several reasons why soybean oil is so widely used. It is said to have a high smoke point, or the temperature at which fats begin to oxidize and become harmful because it forms free radicals. Soybean oil's smoke point is at 450 degrees Fahrenheit, while popular favorite extra-virgin olive oil's smoke point is at 375 F — making soybean oil a good fat to use in high-temperature cooking.

Soybean oil is rich in polyunsaturated fats, which is good for our hearts; and appears to keep our bones healthy as well. It is even said to have omega-3 fatty acids, which is beneficial to heart health and brain functions, per U.S. Soy.

If this all seems too good to be true, research out of University of California at Riverside says that this could well be the case.

Research carried out in 2015 by the University of California at Riverside suggests that the excessive consumption of soybean oil actually "induces obesity, diabetes, insulin resistance, and fatty liver in mice," per ScienceDaily; although if soybean oil is modified to be low in linoleic acid, which is one of its key components, a later study by the same group (in 2017) showed less obesity and insulin resistance in mice. 

But the study did not end there. The team from UC Riverside then looked at the hypothalamus of the mice living on a soybean oil diet, which is when they discovered that certain genes were "not functioning correctly." The finding was significant because as the study's lead author, Margarita Curras-Collazo put it: "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." 

The findings, which were released in the journal Endocrinology, show that the mice who lived on a soybean oil diet saw changes to about 100 genes — and that these are responsible for everything from metabolism to brain functions that trigger diseases like autism or Parkinson's disease. It also saw a drop in oxytocin, or what is known as the "love" hormone.

The research team even said they had tested other oils, and found that the discovery only applied to soybean oil.

While it'd be easy to be concerned about these findings, scientists are quick to point out several points to consider where this study is concerned, per ScienceDaily. Mitigating factors include the facts that the research was conducted on male mice (oxytocin levels are more critical in female mice), and that the results might look vastly different if human subjects are studied. The group also stressed it did not discover proof that soybean oil actually caused autism or Parkinson's disease.

There were other factors in the study that made researchers cautious about the results, including the fact that they weren't able to identify exactly which element or elements in the soybean oil actually caused the changes.

But Frances Sladek, a professor of cell biology at UC Riverside, believes that the findings are enough to show conventional wisdom about fats can be oversimplified. "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," she said. She also adds that now is not the time to ditch the soy out of our diets, because "[m]any soy products only contain small amounts of the oil, and large amounts of healthful compounds such as essential fatty acids and proteins."

And because there is still much we need to learn about when it comes to soybean oil, it is probably best to take that fat — and products that contain it — in moderation.