Researchers find that eating trans-fats may increase the risk of depression

Studies have found that long chain omega 3 fatty acids, from oily fish such as salmon, trout, mackerel and sardines, may be useful in the prevention and treatment of depression and low mood.  Now research has found (1) that eating trans-fats may increase the risk of suffering depression, and that olive oil  may protect against depression.

Trans fatty acids are created through manufacture when liquid vegetable oils are hardened, to a solid or semi-solid state, via a process known as hydrogenation.  (Hydrogenation is when naturally occurring cis-unsaturated double bonds are converted into trans unsaturated double bonds).  The process of hydrogenation also destroys the essential short chain omega 3 fatty acid alpha-linolenic acid from oils (for more information about the health benefits of omega 3 fats please read through my numerous posts on the subject).  Trans fatty acids have been linked to various adverse health effects. 

The study ran from 1999-2010 and involved 12,059 Spanish university graduates with an average age of  37.5 years.  All of the participants were initially free of depression.  At the beginning of the study a detailed and extensive food frequency questionnaire was used to estimate the intake of fatty acids.  During the six year follow-up period any cases of depression, as diagnosed by a physician, were reported.  In this time over 650 new cases of depression were identified.  Results found that trans fatty acids were associated with an increased risk of depression – the more trans fats consumed the higher the risk of depression.  On the other hand the more monounsaturated fat e.g. olive oil consumed the lower the risk, this was also true for polyunsaturated fats e.g. fish oil.  The authors of the study conclude: “A detrimental relationship was found between TFA [trans fatty acid] intake and depression risk, whereas weak inverse associations were found for MUFA [monosunsaturated fatty acid], PUFA [polyunsaturated fatty acids] and olive oil. These findings suggest that cardiovascular disease and depression may share some common nutritional determinants related to subtypes of fat intake”.

Specifically the results found that participants with an elevated consumption of trans-fats (2)presented up to a 48% increase in the risk of depression when they were compared to participants who did not consume these fats,”.   Associate professor Almudena Sánchez-Villegas one of the study authors also said (2)the more trans-fats that were consumed, the greater the harmful effect they produced in the volunteers,”

It is estimated that around 150 million persons worldwide suffer from depression.  In a press release Almudena Sánchez Villegas boldly hypothesises that this may be due (2)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.

It is important to note that this published research (1) took place in 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 another study author (2)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%.”

Please read my previous post for more information about the hypothesized dangers of eating a diet containing trans fats.  Evidence is increasing to support a relationship between improved nutrition and better mental health.  Please read my previous blog posts on depression and mood

(1)Sánchez-Villegas A et al.  2011.  Dietary Fat Intake and the Risk of Depression: The SUN Project. PLoS ONE, 2011; 6 (1): e16268 DOI: 10.1371/journal.pone.0016268

 (2)Press Release.  Public Library of Science (2011, January 26). Eating poorly can make you blue: Trans-fats increase risk of depression, while olive oil helps avoid risk. ScienceDaily. Retrieved January 27, 2011, from­ /releases/2011/01/110126171451.htm

Written by Ani Kowal