Canola oil – time to give it a miss?

Canola oil is one of the widest consumed oils on the planet, but not much is known about how it impacts health. A recent study that was published on December 7 in Scientific Reports by researchers at the Lewis Katz School of Medicine at Temple University suggests that canola oil may be a key figure to worsened memory, worsened learning ability and weight gain in mice which model Alzheimer’s disease. It is the first to suggest that canola oil is more harmful than helpful to the brain.

“Canola oil is appealing because it is less expensive than other vegetable oils, and it is advertised as being healthy,” explains Domenico Praticò, MD, professor in the departments of pharmacology and microbiology and director of the Alzheimer’s Centre at LKSOM, as well as the senior investigator on the study. “Very few studies, however, have examined that claim, especially in terms of the brain.”

Curious about how canola oil affects brain function, Praticò and Elisabetta Lauretti, a graduate student in Pratico’s laboratory at LKSOM and co-author on the new study, focused their work on memory impairment and the formation of amyloid plaques and neurofibrillary tangles in an Alzheimer’s disease mouse model. Amyloid plaques and phosphorylated tau is responsible for the formation of tau neurofibrillary tangles and contributes to neuronal dysfunction, degeneration and memory loss in Alzheimer’s disease. The animal model was designed to simulate Alzheimer’s in humans, progressing from an asymptomatic phase in early life to full-blown disease in aged animals.

Praticò and Lauretti had used this mouse model previously to study the effects of olive oil on the brain. They found those with an olive-oil enriched diet had less amyloid plaque and experienced memory improvement. That study was published earlier this year.

The researchers wanted to discover if canola oil was equally beneficial. They began dividing the mice into two groups at six months of age before there was any development of Alzheimer’s disease. One group was fed a normal diet, while the other was fed a diet supplemented with the human equivalent of about one tablespoon of canola oil daily.

The researchers then assessed the animals at 12 months. One of the first differences observed was in body weight – animals on the canola oil-enriched diet weighed significantly more than mice on the regular diet. Maze tests to assess working memory, short-term memory and learning ability uncovered additional differences. Most significantly, mice that had consumed canola oil over a period of six months suffered impairments in working memory.

With examination of brain tissue, the two groups of mice revealed that those who had the canola-fed diet had a higher level of amyloid plaque and less amyloid beta proteins. The damage was accompanied by a significant decrease in the number of contacts between neurons, indicative of extensive synapse injury.

These findings suggest that long-term consumption of canola oil is detrimental to overall health. The researchers plan on observing a shorter and a longer study to gauge the quantity required when ill-effects are seen in the brain and to observe any impacts on tau phosphorylation.

“We also want to know whether the negative effects of canola oil are specific for Alzheimer’s disease,” Praticò adds. “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.”

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