A new study has demonstrated that the ingestion of trans-fats increases the risk of suffering depression, and that olive oil, on the other hand, protects against this mental illness.

Trans fats are found naturally occurring in very small amounts in meat and dairy products, but the bulk of trans fats in the modern diet are found in many baked goods, snacks and other packaged and processed foods. They are synthetically produced by the partial hydrogenation of vegetable oils, by processing vegetable oils to increase their shelf-life. Unlike other fats, trans fats have no nutritional value to the human body, but have come to be widely used in restaurants and packaged foods, because they hold flavor longer and have a greater shelf life than non-hydrogenated oils.

Study Details

Scientists studied 12,059 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. In this way the researchers confirmed that despite the fact that at the beginning of the study none of the volunteers suffered from depression, at the end of the study 657 new cases had been detected.

Of all these cases, the participants with an elevated consumption of trans-fats "presented up to a 48% increase in the risk of depression when they were compared to participants who did not consume these fats," one author of the article said.

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

Furthermore, the team also analyzed the influence of polyunsaturated fats (abundant in fish and vegetable oils) and of olive oil (a type of monounsaturated fat) 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," emphasized the researcher.

In addition, the research was 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 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%." one of the researchers said.

Finally, the 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 on the risk of cardiovascular disease and on health in general.

Research Paper Details:

Sánchez-Villegas A, Verberne L, De Irala J, et al. Dietary Fat Intake and the Risk of Depression: The SUN Project. PLoS ONE, 2011; 6 (1): e16268.