Olive oil reduces the risk of dying from dementia.
A Harvard University study says that eating more than half a teaspoon of the dressing slashes the risk of passing away from a decline in brain function by 28 per cent.
Scientists are uncertain as to what is driving the effect but have suggested that the antioxidants in olive oil pass through the blood-brain barrier and have a direct impact on cognition.
For the study, researchers analysed 90,000 Americans over a 30-year period, during which 4,749 died.
The findings indicated that those who consumed more than half a teaspoon of olive oil on a daily basis had a 28 per cent lower risk of dying from dementia over the timespan compared to those who never or rarely had the dressing.
Dr. Anne-Julie Tessier, from Harvard's T.H. Chan School of Public Health, said: "Our study reinforces dietary guidelines recommending vegetable oils such as olive oil and suggests that these recommendations not only support heart health but potentially brain health, as well.
"Opting for olive oil, a natural product, instead of fats such as margarine and commercial mayonnaise is a safe choice and may reduce the risk of fatal dementia."