Can olive oil prevent mental illness?

A new study says the ingestion of trans-fats and saturated fats increases the risk of suffering depression and that olive oil protects against this mental illness. 


The study by researchers from Navarra and Las Palmas de Gran Canaria used 12,059 SUN Project volunteers over the course of six years; the volunteers had their diet, lifestyle and ailments analyzed at the beginning of the project, over its course and at the end of the project. The researchers say none of the volunteers reported depression at the beginning of the study but, at the end, 657 new cases had been detected. 

If your correlation/causation errors are so inclined, it means bad diets caused depression.

Participants reported elevated consumption of trans-fats (fats present in artificial form in industrially-produced pastries and fast food, and naturally present in certain whole milk products) and that "presented up to a 48% increase in the risk of depression when they were compared to participants who did not consume these fats," affirmed Almudena Sánchez-Villegas, Associate Professor of Preventive Medicine at the University of Las Palmas de Gran Canaria, first author of the article.

In addition, the study established a dose-response relationship, "whereby the more trans-fats were consumed, the greater the harmful effect they produced in the volunteers," they stated.

The team directed by Miguel Ángel Martínez-González, Professor of Preventive Medicine at the University of Navarra also analyzed the influence of polyunsaturated fats (abundant in fish and vegetable oils) and of olive oil on the occurrence of depression. "In fact, we discovered that this type of healthier fats, together with olive oil, are associated with a lower risk of suffering depression," he said.

Or it could be that depressed food eat more junk food.

They say the results of the study corroborate the hypothesis of a greater incidence of the disease in countries of the north of Europe compared to the countries of the south, where a Mediterranean dietary pattern prevails - some 150 million people may be affected worldwide, where it is considered the principal cause of loss of years of life in those countries with a medium-to-high per capita income.   Poorer countries cannot afford to be depressed.   They can afford junk food, though.  

Almudena Sánchez Villegas says the increase is due "to radical changes in the sources of fats consumed in Western diets, where we have substituted certain types of beneficial fats—polyunsaturated and monounsaturated in nuts, vegetable oils and fish—for the saturated and trans-fats found in meats, butter and other products such as mass-produced pastries and fast food".

The research has been performed on a population with a low average intake of trans-fats, given that it made up only 0.4% of the total energy ingested by the volunteers. "Despite this, we observed an increase in the risk of suffering depression of nearly 50%. On this basis," concluded Miguel A. Martínez, "we derive the importance of taking this effect into account in countries like the U.S., where the percentage of energy derived from these foots is around 2.5%".

Finally, their analysis suggests that both depression as well as cardiovascular disease are influenced in a similar manner by diet, and might share similar mechanisms in their origin. This hypothesis is further suggested by numerous studies that indicate the harmful effect of trans-fats and saturated fats on the risk of cardiovascular disease.