This week a study from Temple University in Philadelphia, USA suggested that a diet rich in Canola oil is linked to worsening memory and reduced learning ability for people with Alzheimer’s disease.. This is the same research team that found olive oil to be beneficial and protective of the brain, so it’s raised a lot of interest. Canola oil is the trade name for an edible oil derived from rapeseed oil by removing some bitter tasting and potentially harmful compounds; in the UK the rapeseed oil on shop shelves is comparable to Canola. The oils are useful in cooking as they have a neutral taste and they’re less expensive than olive oil, which has a similar composition.
The research showed that mice with an Alzheimer’s gene, which were fed a diet enriched with Canola oil. gained weight and performed more poorly in one out of three types of maze tests than mice fed a non enriched diet. There were also differences in brain chemistry, with a particular protein used by neurotransmitter receptors being reduced and one of the brain’s defences against the formation of Amyloid plaque (thought to be implicated in Alzheimer’s disease) was also lowered.
The authors say more research is needed to confirm their results and understand how much oil needs to be consumed before an impact on human brain health can be seen and also to measure outcomes over a longer period. One of the real puzzles is why olive oil was shown to be so good for the brain, whereas Canola or rapeseed oil, which is chemically very similar to olive oil, looks like it may be harmful.