Fast food really is depressing

How do you react when feeling a bit blue or had a really rotten day?

For many of us it may be time to wallow in self-pity or “reward” ourselves with a forbidden or comfort food to cheer ourselves up. But it turns out, that diving into that tub of ice cream or chomping through that second packet of biscuits may increase our risk of developing depression.

Researchers in Spain have published their findings from 12,000 volunteers who participated in a 6 year study, the SUN project (Seguimiento Universidad de Navarra) where their dietary habits, lifestyles and mental health was assessed using questionnaires.

None of the participants had clinical depression at the beginning of the study. Their food intake was based predominantly on the Mediterranean diet. This diet is vegetable based with a relatively low intake of red meat, and a higher intake of fish, olive oil, seeds and nuts. In other words their intake of the “bad fats, the saturated fat and trans fat is low compared to diets of many Northern Europeans, Australians or Americans.

Over the course of six years, 657 participants self reported depression. It was found that of this group, those who had consumed the highest amount of trans fat had a 48% increased risk of developing depression compared to those who had consumed the least. A clear dose response was demonstrated. The higher the level of trans fat consumed, the greater amount of harm produced in the volunteers.

The average Spaniard consumes around 0.4% of their total kilojoules or calories as trans fats or saturated fats, compared to the average American who consumes 2.5% of their total kilojoule intake as these "bad" fats.

Plus the type of trans and saturated fats eaten by the Spanish mostly comes from natural sources such as meat, milk, butter and cheese. Trans fats and saturated fats consumed by Americans are more likely to come from processed snack foods, fried or fast food.

The fact that an almost 50% difference in depression risk was demonstrated in those consuming an already relatively low intake of trans fats, is highly significant when considering the wider global community as a whole.

Depressive illness is very common. It is now estimated that the worldwide incidence of depression is around 150 million people.

Consuming monosaturated fat and polyunsaturated fat such as olive oil is associated with a lower risk of depression.

In a study from Finland it was found that eating a diet with a high level of fish consumption, and a higher level of omega threes, (considered essential for better cognition and mental well being) was found to protect men from depressive illness.

So which comes first? Does eating trans fat cause depression? Or does depression cause us to eat more poorly? In the Spanish study the researchers excluded any cases of depression reported in the first two years of the study. This strengthened the association that it was actually consuming the higher level of trans fat that led to the subsequent development of depression.

The authors noted that consuming a higher level of trans fat is known to be linked to a higher risk of cardiovascular disease. Depression and heart disease have also been noted to go hand in hand. They suggest there may be a similar mechanism at work. High levels of trans fats leads to inflammation in the body, which in the heart can lead to fatty plaques being deposited in the blood vessels, and in the brain may interfere with the brain’s neurotransmitters concerned with regulating mood.

So the next time you are tempted to console yourself with a serve of high calorie, high trans fat ice cream, cake or pizza. Spare a thought for your brain and consider whether it really it worth the short term pleasure, which puts you at higher risk of longer term depression.

We truly are what we eat.

Refs: Almudena Sánchez-Villegas, Lisa Verberne, Jokin De Irala, Miguel Ruíz-Canela, Estefanía Toledo, Lluis Serra-Majem, Miguel Angel Martínez-González. Dietary Fat Intake and the Risk of Depression: The SUN Project. PLoS ONE, 2011; 6 (1): e16268 DOI: 10.1371/journal.pone.0016268

Suominen-Taipale AL, Partonen T, Turunen AW, Männistö S, Jula A, et al. 2010 Fish Consumption and Omega-3 Polyunsaturated Fatty Acids in Relation to Depressive Episodes: A Cross-Sectional Analysis. PLoS ONE 5(5): e10530. doi:10.1371/journal.pone.0010530