Spanish investigators from the University of Las Palmas de Gran Canaria found that compared with their counterparts who consumed diets low in TFAs, individuals with elevated levels of trans-fats had a 48% increased risk for depression.  These findings, say researchers, suggest cardiovascular disease and depression “may share some common nutritional determinants related to subtypes of fat intake.

“The results were not surprising [and] I think the message is clear: ‘try to eat healthy,'” lead study author Almudena Sánchez-Villegas, PhD said.  “Avoid some types of fats, such as trans and saturated fatty acids, and increase the intake of polyunsaturated and monounsaturated fat; it's better to consume olive oil than margarine or butter, better to use low-fat dairy than high-fat dairy, and better to eat fish than to consume meat or meat products; avoid fast and processed foods and commercial bakery; and try to increase your consumption of fruits, vegetables, and nuts,” she said.  Following this advice, she added, will not only protect against cardiovascular disease but, as suggested by this and other recent research, also mental illness.  The investigators note that this is the first cohort trial to assess “such a broad spectrum of fat subtypes in relation to depression risk.”

“Depression affects more than 150 million people worldwide. However, relatively few [longitudinal] studies have analyzed the effect of diet on this disease,” said Dr. Sánchez-Villegas.  She added that several previous studies have suggested a link between cardiovascular disease and depressive disorders via inflammatory, endothelial, or metabolic processes.

“The adverse effects of trans-fatty acids on cardiovascular disease are thought to be mediated by increases in proinflammatory cytokines and endothelial dysfunction. We decided to analyze the possible association between trans-fatty acids and depression because low-grade inflammatory status and endothelial dysfunction are common among depressed patients,” Dr. Sánchez-Villegas explained.
“On the other hand, olive oil contains some bioactive polyphenols with important anti-inflammatory properties. This anti-inflammatory capacity…could also improve the function of the endothelium.”

“The finding regarding the [TFA] is of particular importance. There are no data that I'm aware of to date that have actually looked at its intake and risk of mental health problems,” said Dr. Jacka.
“I think this adds to the body of literature that's been developing for the last 12 months showing that dietary factors are a potential real importance in both the risks of mental health and the progress of mental illnesses. And now we've got a little bit more information on specific nutrients.”

She noted that TFA is “a particular problem in the food chain,” especially in the United States since Americans tend to consume more TFAs than populations in other countries.

PLoS ONE. Published online January 26, 2011. Full text