Excessive consumption of red meat, butter and other foods that contain high levels of saturated fat increases the risk of developing Alzheimer's disease - the most common form of dementia.
A US study from Harvard University found that women who frequently ate foods high in this type of fat had memory problems.
For comparison - stronger memory have those who provide more monounsaturated fats by consuming olive oil, sunflower oil, seeds, nuts and avocados.
Following the changes in cognitive function, the researchers found that it was not so much the amount that mattered as the type of fat consumed.
The researchers compiled a report based on a review of data from 6,000 women who performed a series of cognitive tests over a four-year period and answered questionnaires about their lifestyle and diet.
Replacing harmful fats with healthy ones is a relatively simple dietary modification that can help prevent memory loss, says Dr. Oliva Okereke of the research team.
The diet useful for cell membranes, including brain cells, includes monounsaturated fats and polyunsaturated fats, which are rich in omega-3 fatty acids.
The report is published in the Annals of Neurology.
According to the advice of doctors, the amount of fat we eat should not exceed 25-35% of the total daily calories. At least 20% of the fat should be monounsaturated, 10% - polyunsaturated, and the remaining 5-7% - saturated.