Canola oil harms the brain and helps put on weight.

Canola oil is appealing because it is less expensive than other vegetable oils, it is advertised as being healthy, and promoted by the heart foundation.
In this study the mice received either regular chow or a chow diet supplemented with canola oil for 6 months. At this time point we found that chronic exposure to the canola-rich diet resulted in a significant increase in body weight and impairments in their working memory together with decrease levels of post-synaptic density protein-95, a marker of synaptic integrity, and an increase in the ratio of insoluble Aβ 42/40.
 
They reported their findings do not support a beneficial effect of chronic canola oil consumption on two important aspects of AD pathophysiology which includes memory impairments as well as synaptic integrity.
Today canola oil is the third largest vegetable oil by volume after palm and soybean oil worldwide, and in the United States is one of the most widely used oil for human consumption second only to soybean oil. While many studies have investigated the relationship between olive oil with disease incidence, mortality and biomarkers for diseases, studies with canola oil are mainly focused only to biomarkers. Limited and not conclusive scientific evidence would suggest some benefit for canola oil consumption, but results from studies implementing diets containing canola oil in experimental animal models have provided us with conflicting data. On the other hand, studies have consistently demonstrated a beneficial effect of olive oil in different mouse models of neurodegeneration. By contrast, no data are available on the effect that canola oil consumption may have on any of these models and the development of AD.
 
The authors had previously used the same mouse model in an investigation of olive oil and found the opposite to canola. Alzheimer mice fed a diet enriched with extra-virgin olive oil had reduced levels of amyloid plaques and phosphorylated tau and experienced memory improvement. In support of this the Mediterranean diet which is rich in olive oil is associated with a reduced risk of developing mild cognitive impairment and AD, and a reduced risk of progressing from mild cognitive impairment to AD among its many health benefits.
Rapeseed oil (known also as canola oil) has emerged as a potential substitute for olive oil since has a similar monounsaturated fatty acids content to that of olive oil and an overall favorable fatty acid profile. As result, in recent years the consumption of canola oil has significantly increased in non-Mediterranean countries, due to the lower cost compared with olive oil and the perception that it shares the health benefits of the olive oil.