Study finds canola oil unhelpful against Alzheimer’s in mice

A U.S. study of mice genetically engineered to model Alzheimer’s disease has found those on a diet rich in canola oil were more prone to certain markers of the disease than the same type of mice on regular chow.

The Canola Council of Canada, the value-chain industry group for the world’s top canola-exporting country, said Friday it’s reviewing the study, done by a team from Philadelphia-based Temple University.

Dr. Domenico Pratico, director of the Alzheimer’s Center at Temple’s Lewis Katz School of Medicine, and grad student Elisabetta Lauretti published the study Thursday in an online journal, Scientific Reports.

In a study published in June, Pratico and Lauretti looked at the same model of transgenic mice fed a diet rich in extra-virgin olive oil. That study, they said, found “reduced levels of amyloid plaques and phosphorylated tau and experienced memory improvement” against the same type of mice fed regular chow.

Noting in the new canola oil study that the public’s “consumption of canola oil has increased, due to lower cost compared with olive oil and the perception that it shares its health benefits,” the team used the same type of transgenic mice as in the olive oil study.

The Temple study split the mice into two groups at age six months, before the mice developed signs of Alzheimer’s, then assessed the mice at age 12 months, including maze tests and studies of brain tissue. The canola group’s diet included “the human equivalent of about one tablespoon of canola oil daily.”

This specific mouse model used in this and other research is designed to “recapitulate Alzheimer’s in humans, progressing from an asymptomatic phase in early life to full-blown disease in aged animals.”

In their paper, the Temple team wrote, “chronic exposure to the canola-rich diet resulted in a significant increase in body weight and impairments in (the mice’s) working memory together with decreased levels of post-synaptic density protein-95, a marker of synaptic integrity.”

The study also showed “greatly reduced” levels of amyloid beta 1-40, the more soluble form of the amyloid beta proteins, in the canola oil group. Amyloid beta 1-40, the team said, is considered to act as a buffer for the “more harmful” insoluble form, amyloid beta 1-42.

“In our model, this change in ratio resulted in considerable neuronal damage, decreased neural contacts, and memory impairment,” Pratico said Friday in a university release.

“Taken together, our findings do not support a beneficial effect of chronic canola oil consumption on two important aspects of (Alzheimer’s) pathophysiology which includes memory impairments as well as synaptic integrity,” they wrote in their report.

“Although we recognize that more studies are needed to investigate the biological effects of this oil, our data would not justify the increasing tendency of replacing olive oil with canola oil as part of a good and healthy dietary alternative in non-Mediterranean countries.”

Promoting olive oil consumption “could be a difficult task, in part for the fact that this ingredient is generally more expensive than other cooking oils,” the Temple team wrote.

Canola oil, which has a “similar” monounsaturated fatty acids content to that of olive oil and an “overall favourable” fatty acid profile, is cheaper by comparison, they noted.

The study’s findings on body weight suggested the added canola oil provided extra calories to the mice — an observation the team said sits “in contrast with previous reports showing that chronic diet supplementation with canola oil had no effect on the average animal body weight.”

The team said they “interpret this discrepancy as secondary to the different strains of mice that were implemented in those studies, and probably the length of our study.”

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“Even though canola oil is a vegetable oil, we need to be careful before we say that it is healthy,” Pratico said in Temple’s release. “Based on the evidence from this study, canola oil should not be thought of as being equivalent to oils with proven health benefits.”

For its part, the Canola Council said Friday it is “reviewing the research in greater detail” and will post information on its website if there’s more to share.

The Temple study “was conducted using a mouse model and is not a human clinical trial,” the Canola Council said, noting clinical studies “have been going on for decades involving thousands of human volunteers to examine canola oil and its effects on the body.”

The council also noted a scientific literature review, published in Nutrition Reviews in May 2013, covering 40 research studies related to the health benefits of canola oil.

That review pointed to “substantial reductions in total cholesterol and low-density lipoprotein cholesterol, as well as other positive actions, including increased tocopherol levels and improved insulin sensitivity, compared with consumption of other dietary fat sources.”

The U.S. Food and Drug Administration in 2006 also authorized a “qualified” health claim about canola oil’s ability to reduce the risk of heart disease when used in place of saturated fat, the council noted. — AGCanada.com Network