The team used 6-month-old mouse models to test the link between the oil and its influence on Alzheimer's disease. Their study showed that besides brain damage, canola oil may be also linked to weight gain.
"Canola oil is appealing because it is less expensive than other vegetable oils, and it is advertised as being healthy", explained Dr. Domenico Praticò, professor in the Departments of Pharmacology and Microbiology and Director of the Alzheimer's Center at the university's school of medicine, as well as senior investigator on the study. Researchers had previously used the same mouse model in an investigation of olive oil, and found that mice fed a diet enriched with extra-virgin olive oil had reduced levels of amyloid plaques and phosphorylated tau and experienced memory improvement which is contrary to the effects that canola oil had. "Very few studies, however, have examined that claim, especially in terms of the brain". The two factors are what contribute to neuronal dysfunction and degeneration and memory loss in Alzheimer's disease.
So the researchers set out to work with mice that had been engineered to contract Alzheimer's disease in the same way the condition affects humans: asymptomatic in early life and full-blown cognitive impairment when the rodents aged. The canola-oil group also had gained a fair bit more weight than their non-oil-eating studymates.
As a result, in the brains of the mice that were on the oil-rich diets, an increase in amyloid plaques was noted with the substances wrapping around neurons, decreasing the number of contacts between them and pointing to serious synapse injuries. Most significantly, it was noticed that mice that had consumed canola oil over a period of six months suffered impairments in working memory.
The decline in cognitive function in the group of mice fed the oil-rich diet also corresponded to chemical changes in the brain. Maze tests were conducted to observe memory and learning ability. "Even though canola oil is a vegetable oil, we need to be careful before we say that it is healthy", Pratico concluded. The next step these researchers would like to take is studying the effects of consumption of canola oil over a shorter duration to find the minimum effects of exposure.
The findings suggest that long-term consumption of canola oil may not be beneficial to your brain health.