Trans-Fats Linked to Increased Depression Risk

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Consumption of trans-unsaturated fatty acids (TFAs or trans-fats) has been

linked to a significantly increased risk for depression. On the other hand,

olive oil, monounsaturated fatty acids (MUFAs), and polyunsaturated fatty

acids (PUFAs) appear to have a protective effect and lower depression risk,

new research suggests.

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, told *Medscape

Medical News.*

" 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. "

The study is published in the January issue of *PLoS ONE.*

*150 Million Affected*

" 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 researchers evaluated data on 12,059 university graduates (mean age,

37.5 years; 58% female) from the Seguimiento Universidad de Navarra (SUN)

project, an ongoing study initiated in 1999 to assess the effect of several

dietary factors and lifestyle variables on chronic diseases, including

cardiovascular disease, hypertension, obesity, and depression.

Mailed questionnaires are sent biannually to all SUN participants. Those

selected for this analysis completed at least the baseline questionnaire and

1 follow-up questionnaire before May 2010.

Participants were queried about intake of fatty-acids, PUFAs, TFAs, MUFAs,

olive oil, seed oils, butter, and margarine. They were also asked about

medical, sociodemographic, and lifestyle variables.

None of the participants had been diagnosed as having depression before

study entry. They were classified as new cases of depression if, at

follow-up, they reported they had been diagnosed as having the disorder or

had initiated therapy with antidepressants.

*Detrimental Effect *

Results showed that 657 new cases of depression were identified during a

median follow-up time of 6.1 years.

Multivariable-adjusted analysis showed a significant dose-response

relationship between TFA intake and depression incidence (trend, *P* =

..003).

" The magnitude of this association was robust and persisted [and] results

did not substantially change after adjusting for potential lifestyle or

dietary confounders, including adherence to a Mediterranean dietary

pattern, " investigators report.

A statistically significant inverse dose-response relationship was obtained

for total MUFA (trend, *P* = .05) and PUFA (trend, *P* = .03) intake. Olive

oil was also inversely associated with depression risk (*P* = .03), although

" this relationship was attenuated after adjustment for the adherence " to a

Mediterranean dietary pattern.

" Our results showed a protection of cardioprotective fats (PUFA and MUFA)

and a detrimental effect of TFA on depression risk. However, our findings

need to be confirmed by further prospective studies, " the researchers write.

Dr. Sánchez-Villegas reported that the investigative team has received

several grants from the Spanish Ministry of Health to further assess the

association between dietary factors and depression.

" We are [also] evaluating the effect of diet and physical activity on

quality of life in the SUN project, " she said.

*'Major Implications' for America*

" I think this is a really important study, " Felice N. Jacka, PhD, research

fellow at Deakin University in Melbourne, Australia, told *Medscape Medical

News*.

" 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.

A recent study conducted by Dr. Jacka and reported by *Medscape Medical News

* <http://www.medscape.com/viewarticle/715239> showed that a " whole " diet

characterized by vegetables, fruit, whole grains, and high-quality meat and

fish decreases both depression and anxiety. It also showed that those with a

more " Western type diet " high in refined or processed foods and saturated

fats had an increased risk for depression.

" In Australia we have very low levels of trans-fatty acids. In Spain it

would seem that they have moderate levels, and in America they have

extremely high levels, relatively speaking, " she said.

" This new finding of a very clear dose-response relationship between the

level of trans-fatty acids and risk for depression over time has, I think,

major implications for America. "

Dr. Jacka said that an association between dietary intake and mental health

risk has now been shown " all across the world, " including in Spain,

Australia, the United States, Britain, Norway, and Japan.

" It's been found in young people, middle-aged people, and the elderly. And

the effect size has been roughly the same throughout the studies, which is

quite remarkable in a new field — to find such consistency, " she reported.

Although all have been observational studies, with no interventional studies

conducted yet, " we believe that based on the evidence, physicians should

certainly be considering diet as well as exercise level when they're

treating patients for mental illness, " said Dr. Jacka.

" Plus, from a public health perspective, governments need to be looking at

public policy and health promotion, especially in the States. "

*Beyond Depression*

Gómez-Pinilla, PhD, agrees that this finding is particularly

important for the United States because Americans tend to consume more TFAs

than populations in other countries.

" Clinicians should instruct patients about the importance of diet and maybe

even educate them about what they should and shouldn't eat, " Dr.

Gómez-Pinilla, a professor in the Department of Neurosurgery at the

University of California, Los Angeles, and part of the UCLA Brain Injury

Research Center, told *Medscape Medical News.*

Dr. Gómez-Pinilla said his center has been looking at the effect of diet on

specific brain mechanisms in several animal models.

" I think the results of this study are important, and I think people should

be more aware that the risk factors of diet can also apply across several

neurological disorders beyond depression.

" For example, type of diet can be a factor in the healing process of

traumatic brain injuries. The overall application for psychiatrists, in

terms of these types of findings, is just very exciting, " said Dr.

Gómez-Pinilla.

*The study was funded by the Spanish Government Instituto de Salud

III, Fondo de Investigaciones Sanitarias, and the Navarra Regional

Government. The study authors and commentators have disclosed no relevant

financial relationships.*

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

text<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0016268>

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