Alzheimer's Symptoms Worsened by Canola Oil—and It Could Cause Onset of Dementia, Scientists Warn

Canola oil may worsen the symptoms and onset of dementia, according to latest research. Home chefs who cook at high temperatures may want to find an alternative. Sean Gallup/Getty Images

Cooking with canola oil is extremely common, but a new study might make you think before subbing it in for the ever-popular olive. Researchers from Temple University found that canola decreased learning ability, inhibited memory and led to weight gain for mice with Alzheimer's disease.

Related: Symptoms of dementia: Study finds inability to smell peppermint linked to disease

The findings were published today in Scientific Reports and offer new insight into how the very common product could be impacting our brains. Very little current research focusing on this area exists.

"Canola oil is appealing because it is less expensive than other vegetable oils, and it is advertised as being healthy," study co-author Dr. Domenico Praticò, said in a statement. "Very few studies, however, have examined that claim, especially in terms of the brain." Praticò directs the Alzheimer's Center at Lewis Katz School of Medicine at Temple University.

The team used mice engineered to have Alzheimer's disease, splitting them into two groups when they were six months old (before any signs emerged). The control group was given a standard diet and the experimental group was given a supplement that equaled roughly two tablespoons of canola oil each day.

When the animals were assessed at a year old, the team noticed one stark difference: Mice who consumed canola oil were heavier than their control counterparts. But then, the scientists performed tests on the animals to study short-term memory, working memory (which helps us remember things like our favorite cake recipe) and how well mice could learn. They found that the mice eating canola oil performed poorly in all three areas.

A canola oil crop in full bloom on the Canadian prairie near Fort Macleod, Alberta. Todd Korol/Reuters

According to MedicalXpress, the tests also revealed that the animals had less of a protein known as amyloid beta 1-40, which offers protection from another amyloid-beta protein, 1-42 (also referred to as beta-amyloid 42), which can harm our brains. This decrease led to more amyloid plaques, a marker of Alzheimer's. According to the National Institutes of Health, patients with the disease develop these plaques after the toxic beta-amyloid 42 clump together in the brain, inhibiting normal function.

"Amyloid beta 1-40 neutralizes the actions of amyloid 1-42, which means that a decrease in 1-40, like the one observed in our study, leaves 1-42 unchecked," Praticò explained in MedicalXpress.

In simple terms, the Amyloid beta 1-40 wasn't able to offer its normal protection against amyloid 1-42 because there were fewer of the 1-40 molecules acting as a buffer, which scientists believe could be due to eating canola oil.

"In our model, this change in ratio resulted in considerable neuronal damage, decreased neural contacts, and memory impairment," Praticò said.

The scientists plan on conducting another study to determine how canola oil impacts brain health in the short term, and whether it causes the onset of other diseases.

"We also want to know whether the negative effects of canola oil are specific for Alzheimer's disease," Praticò said. "There is a chance that the consumption of canola oil could also affect the onset and course of other neurodegenerative diseases or other forms of dementia."

Made of genetically modified rapeseed, a plant in the mustard family, canola oil has often been thought of as a healthier choice for cooking because it's low in saturated fat and has been shown to reduce cholesterol when compared to diets with higher saturated fat contents. (Fun fact: The word "canola" is a combination of Canada, which refers to its Canadian origins, and oleum, which is Latin for oil.)

Despite its prevalence in our diets, this new research suggests you might want to delve more into learning about the oil before using it as your go-to—which brings up a whole new conundrum since olive oil isn't meant for high-temperature cooking. Bon Appetit recommends options like avocado, sunflower and grapeseed oils for their higher smoke points.