Widely consumed soybean oil not only leads to obesity and diabetes but may also affect neurological conditions like autism, Alzheimer's disease, anxiety and depression, report researchers from University of California Riverside, including one of Indian origin.
In a study conducted on mice, the scientists found pronounced effects of the soybean oil on the hypothalamus where a number of critical processes take place.
The research team discovered nearly 100 genes - including the 'love hormone' oxytocin produced in hypothalamus -- affected by the soybean oil diet.
"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, an associate professor of neuroscience and lead author on the study published in the journal Endocrinology.
The research team has not yet isolated which chemicals in the oil are responsible for the changes they found in the hypothalamus.
"But they have ruled out two candidates. It is not linoleic acid, since the modified oil also produced genetic disruptions; nor is it stigmasterol, a cholesterol-like chemical found naturally in soybean oil," the study noted.
Identifying the compounds responsible for the negative effects is an important area for the team's future research.
"This could help design healthier dietary oils in the future," said Poonamjot Deol, first author on the study.
"If there's one message I want people to take away, it's this: reduce consumption of soybean oil," Deol added.
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.
They believe this discovery could have ramifications not just for energy metabolism,but also for proper brain function and diseases such as autism or Parkinson's disease.
"However, it is important to note there is no proof the oil causes these diseases," the authors wrote.
Te same 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.
The team said the findings only apply to soybean oil -- not to other soy products or to other vegetable oils.
"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".
This study utilized male mice. Because oxytocin is so important for maternal health and promotes mother-child bonding, similar studies need to be performed using female mice.
Coconut oil, which contains saturated fats, produced very few changes in the hypothalamic genes, said the researchers.