https://www.yahoo.com/lifestyle/m/e3ddbf52-1c57-35af-888d-90a7639ef3a1/ss_canola-oil-linked-to.html
Canola is generally considered a
healthy oil thanks to its ability to reduce LDL cholesterol in the blood
and lower the risk of heart disease. A new animal study out of Temple
University, though, has shown that the vegetable-based fat increases
substances in the brain that can lead to Alzheimer's disease.
"Canola oil is appealing
because it is less expensive than other vegetable oils, and it is
advertised as being healthy," explained study senior author Domenico
Praticò, director of the Alzheimer's Center at Temple's Lewis Katz
School of Medicine. "Very few studies, however, have examined that
claim, especially in terms of the brain."
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. At six months of age, when the mice still had no
symptoms, they were split into two groups. One group was given a normal
diet while the other had a normal diet plus the addition of
approximately two tablespoons of canola oil each day.
Six months later, maze
tests revealed the mice on the canola diet showed a decline in their
working memory capacities compared to the other group. The canola-oil
group also had gained a fair bit more weight than their non-oil-eating
studymates.
The decline in cognitive
function in the group of mice fed the oil-rich diet also corresponded to
chemical changes in the brain. The canola-oil group showed a decrease
in the levels of a protein known as amyloid beta 1-40. Amyloids are well-known in Alzheimer's research
as the substances that form sticky clumps in the brain. But amyloid
beta 1-40 actually helps prevent those clumps from forming by buffering
amyloid beta 1-42, an insoluble form of the protein, so a reduction
isn't a good thing.
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. As synapses – the space between neurons where chemical signals
are transmitted – are key to memory functions,the findings fit with the
decreased ability the mice demonstrated in running the maze.
"Even though canola oil is a
vegetable oil, we need to be careful before we say that it is healthy,"
Praticò said. "Based on the evidence from this study, canola oil should
not be thought of as being equivalent to oils with proven health
benefits."
One such oil is olive oil, which Praticò and his team showed could actually reduce amyloid plaques in mouse models in a study earlier this year.
The next step for the
researchers is to conduct studies over a shorter period of time to see
just how quickly Alzheimer's-disease-affected brains begin showing the
damage. Even though the study showed no impact from canola oil on other
disease-related markers such as inflammation or tau – another protein
linked to Alzheimer's – the researchers say they will also delve into
the role the fat might play in other conditions.
"We also want to know whether
the negative effects of canola oil are specific for Alzheimer's
disease," Dr. Praticò concluded. "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."
The research has been published in the journal Nature.
Source: Temple University via EurekAlert
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