The Short Answer

Research shows that canola oil worsens memory and promotes amyloid plaque buildup linked to dementia. For people with autoimmune conditions, including Hashimoto’s low thyroid, avoiding canola oil and switching to brain-healthy fats like olive oil, avocado oil, and ghee is an important dietary step to protect cognitive function.

Why Canola Oil Damages Brain Health in Autoimmune Patients

We’ve long been told that canola oil is healthy. After all, major grocery chains proudly display it as an ingredient in prepared foods. But scientists have revealed a darker truth: canola oil worsens memory and promotes amyloid plaque, a primary marker of Alzheimer’s disease. This matters for autoimmune patients, particularly those with Hashimoto’s low thyroid, which already increases the risk of dementia.

Brain health symptoms are frequently misattributed to autoimmune conditions themselves. Conventional doctors may dismiss cognitive decline as part of your condition, rather than addressing the underlying dietary or metabolic factors that worsen it.

What the Research Shows About Canola Oil and Memory

The idea for this study came from a similar investigation using extra-virgin olive oil. Researchers fed mice with Alzheimer’s disease a diet rich in olive oil. Compared to the control group, these mice showed improved memory and reduced amyloid plaques and phosphorylated tau, which creates the neurofibrillary tangles that cause Alzheimer’s brain degeneration.

Researchers then repeated the study using canola oil, one of the cheapest and most widely used oils globally. After one year, the mice fed the equivalent of two tablespoons of canola oil daily showed:

Significantly increased body weight compared to the control group

Impairments in working memory

Reduced levels of beneficial amyloid beta (amyloid beta 1-40), which acts as a protective buffer against harmful amyloid beta 1-42

Poor connectivity between neurons in the brain, with extensive synapse injury that disrupts memory formation and retrieval

When protective amyloid beta 1-40 decreases, the harmful 1-42 form is left unchecked to degenerate brain tissue. The scientists plan follow-up studies to determine how quickly neuron damage begins after regular canola oil consumption and whether it impacts other brain-degenerative diseases.

Better Fat Choices for Brain Protection

Given the increased risk of cognitive decline in autoimmune patients, avoiding canola oil daily or regularly is worth the effort. The challenge is that prepared foods and restaurant meals often contain canola oil, soybean oil, or processed vegetable oils, none of which support brain health. Particularly avoid hydrogenated or partially hydrogenated oils, which are also linked to memory loss.

The brain is made mostly of fat. The fats you consume determine the structure of your brain cells and how well they communicate with one another. Hydrogenated fats make cell membranes more rigid and less able to function properly.

Instead, use extra-virgin olive oil, avocado oil, coconut oil, and ghee for cooking and dressings. For people managing autoimmune conditions, dietary choices matter beyond just brain health; foods that trigger inflammation can worsen autoimmune flares and damage thyroid tissue.