Posted on Jan 17, 2020, 1 p.m.
Recent research from UC Riverside demonstrates that soybean oil leads to obesity, diabetes, and may also affect neurological conditions such as anxiety, depression, autism, and Alzheimer’s disease.
Soybean oil is the most commonly produced and consumed edible oil in America according to the US Department of Agriculture, it is widely used for fast frying, fed to livestock, as well as being added to packaged foods.
However, according to research in all likelihood it is not healthy for human consumption, and it most certainly is not good for mice. This study was published in the journal Endocrinology which compared mice fed with three different diets being high in fat: soybean oil, coconut oil, and soybean oil modified to be low in linoleic acid.
The same research team found that soybean oil induces fatty liver, diabetes, insulin resistance, and obesity in mice studies during 2015, as well as if the oil is engineered to be low in linoleic acid it induces less insulin resistance and obesity in 2017 mice studies.
This recent study did not yield any differences between the modified and unmodified soybean oil’s effect on mice brains, specifically pronounced effects were found on the hypothalamus, which is where a number of critical processes take place.
"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," said Margarita Curras-Collazo, a UCR associate professor of neuroscience and lead author on the study.
A number of genes in the animals fed soybean oil were determined not to be functioning correctly, one of which produces the love hormone oxytocin that in the mice fed soybean oil the levels of oxytocin in the hypothalamus decreased. Additionally, roughly 100 other genes were also discovered to be affected by the soybean oil diet, and it's believed the discovery may have ramifications for more than just energy metabolism, reaching to proper brain function and diseases such as Parkinson’s disease and autism.
It was noted that there is no proof the oil causes these diseases, and these findings only apply to soybean oil not other soy products or other vegetable oils. Additionally this study was conducted on mice and animal study findings don’t always translate to humans. Male mice were utilized in this study, due to the importance of oxytocin for maternal health additional studies are required utilizing female mice.
"Do not throw out your tofu, soymilk, edamame, or soy sauce," said Frances Sladek, a UCR toxicologist and professor of cell biology. "Many soy products only contain small amounts of the oil, and large amounts of healthful compounds such as essential fatty acids and proteins."
The chemicals in the oil that are responsible for the changes in the hypothalamus have not yet been isolated, but the researchers did rule out two candidates: it is not linoleic acid since the modified oil also produced genetic disruptions, and it is not stigmasterol which is a cholesterol like chemical found naturally within soybean oil.
Coconut oil containing saturated fat produced very few changes in the hypothalamic genes, identifying the compounds that are responsible for the negative effects may be an important area for future investigation by the research team.
“This could help design healthier dietary oils in the future," said Poonamjot Deol, an assistant project scientist in Sladek's laboratory and first author on the study.
"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," Sladek said.
"If there's one message I want people to take away, it's this: reduce consumption of soybean oil," Deol said about the most recent study.
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