image courtesy of http://www.sxc.hu/
...And the D doesn't stand for donuts.
You have probably heard a great deal about the evils of trans fats, which are largely man-made fats created with the intention of promoting longer shelf-life of processed snacks like donuts, cookies, and chips. These artificial fats have been found to not only increase unhealthy forms of cholesterol, but also decrease the healthy forms. As such, they have been linked to obesity and heart disease, and are considered so harmful to our health that the FDA now requires all food containing them to be labeled as such, and New York City has banned the use of trans fats in all of its restaurants.
The Surprising Link Between Depression and Heart Disease
What you might not know is that medical and psychological researchers have also been busy investigating a surprising link between heart disease and risk for depression – the field is still teasing out all of the hows and whys, but it appears clear that depressed people demonstrate elevations in known risk factors for cardiovascular disease and that depression after the onset of heart disease is linked to greater mortality.
Exploring the Trans Fat-Depression Link
A study performed by Almudena Sánchez-Villegas at the University of Las Palmas de Gran Canaria in Spain and reported in PLoS (a peer-reviewed online journal open to all fields of study) suggested that at least part of this association between depression and cardiac risk factors may be due to diet--specifically, consumption of trans fats.
These researchers tracked over twelve thousand college graduates over six years. None of the participants were depressed at the start of the study; 657 had experienced an episode of depression by the end of the study.
At the start of the study, participants completed a 136-item questionnaire aimed at getting a clear snapshot of their current diet. Over the six years of follow-up, participants reported whether they had received a diagnosis of depression from a professional and/or began taking antidepressants. The researchers classified the participants into five groups based on their level of trans fat intake at the start of the study and examined whether rates of depression differed by diet group.
What The Researchers Found
They discovered a startling relationship between trans fat intake and risk for depression – compared to the group with the lowest intake of trans fat, the group eating the highest amounts of trans fats had a forty-eight percent greater rate of depression over the six years of follow-up. These findings remained significant even when the researchers performed a number of analyses to test for alternative explanations (for instance, whether the low group also followed the Mediterranean diet known to be heart-healthy).
Wrapping It Up
The authors propose that a diet high in trans fats may be a common pathway to both heart disease and depression. You can read more about the possible physiological mechanisms behind the trans fat-depression link in this story in the LA Times.
Clearly more research is needed. The researchers controlled for a number of variables but neglected others (for instance, life stressors or diet during the follow-up period), and no definitive cause and effect conclusions can be made from this single study.
My personal recommendation? No trans fat is a healthy amount of trans fat. Pass on the donuts.
Sarah Rose Cavanagh, Ph.D., is professor of psychology in affective science at Assumption College in Worcester, Massachusetts. To learn more about her research, please visit http://bit.ly/sarahrose.
