The over-con­sump­tion of soy­bean oil may have an impact on inflam­ma­tion, obe­sity and dia­betes, as well as neu­ro­log­i­cal con­di­tions such as autism, Alzheimer’s dis­ease, anx­i­ety and depres­sion.

New research from the University of California, Riverside, has found that the con­sump­tion of soy­bean oil in mice is linked to the dys­reg­u­la­tion of the expres­sion of about 100 dif­fer­ent genes in 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, a pro­fes­sor of neu­ro­science at UC Riverside and lead author on the study, said.

The dys­reg­u­la­tion of these genes leads to the over or under-pro­duc­tion of hor­mones – such as oxy­tocin and vaso­pressin – which have meta­bolic, inflam­ma­tion and neu­ro­log­i­cal rel­e­vance.

The study found that mice fed diets high in soy­bean oil became more glu­cose intol­er­ant and expe­ri­enced more weight gain com­pared with mice fed a high-fat diet with coconut oil. Mice fed the high soy­bean oil diet also expe­ri­enced the dys­reg­u­la­tion of genes asso­ci­ated with autism, Alzheimer’s dis­ease, depres­sion, Parkinson’s dis­ease and schiz­o­phre­nia.

“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 researchers wrote in the study, which was pub­lished in the jour­nal, Endocrinology.

While the two main chem­i­cal com­po­nents of soy­bean oil – linoleic acid and stig­mas­terol – were found not to be respon­si­ble for the dys­reg­u­la­tion, researchers are yet to iden­tify what is respon­si­ble for the dys­reg­u­la­tion.

“An impor­tant caveat of our study is that we do not know if the soy­bean oil is directly affect­ing the brain,” the research team told Olive Oil Times in an email. ​“It could be that since soy­bean oil causes obe­sity and dia­betes (at least in mice), it is either the obese state or the dia­betic state that actu­ally causes the change of gene expres­sion in the brain.”

“Many organs play a role in obe­sity, in addi­tion to the hypo­thal­a­mus,” the research team added. ​“These include the liver, mus­cle, pan­creas and fat (adi­pose tis­sue).”

However, the researchers said that the impli­ca­tions of the study were clear, even if the organic chem­istry was not.

“We rec­om­mend that you avoid con­sum­ing too much soy­bean oil,” the research team said. ​“A lit­tle bit is not harm­ful – soy­bean oil per se is not toxic – and in fact, it is help­ful in that it pro­vides linoleic acid, an essen­tial fatty acid that we must get from the diet.”

“But we only need about one to two per­cent linoleic acid in our diet,” the research team added. ​“Many Americans are cur­rently tak­ing in as much as 10 per­cent linoleic acid, due to the increased con­sump­tion of soy­bean oil.”

The trou­ble with soy­bean oil is that it has become ubiq­ui­tous in the American diet and is increas­ingly dif­fi­cult to avoid.

“Unfortunately, in the United States it is very dif­fi­cult to avoid soy­bean oil. We often do not have a choice,” the researcher team said. ​“Most restau­rants in the U.S. use soy­bean oil as it is inex­pen­sive (soy­beans are easy to grow which makes them a great crop)… Many processed foods con­tain soy­bean oil, even ones that appear to be healthy.”

“Products from farm ani­mals likely have soy­bean oil or its com­po­nents that can make their way to human diet as well,” the research team added. ​“This is because many times soy­bean oil… is added to ani­mal feed… in order to meet rec­om­mended energy require­ments and in some cases for fat­ten­ing up the ani­mals.”

It also remains unclear whether replac­ing soy­bean oil with health­ier oils, such as extra vir­gin olive oil, would have an impact on gene dys­reg­u­la­tion.

“We can­not know what effect if any olive oil might have on gene expres­sion,” the researcher team said. ​“We would have to do the exper­i­ment.”

• Endocrinology


• University of California, Riverside