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Trans fats raise depression risk

People who eat trans and saturated fats more likely to become depressed

Louise Prime

Thursday, 27 January 2011

Eating trans and saturated fats raise the risk of suffering depression, researchers report. Their study, published online today in PLoS ONE, found a dose-response relationship, but even fairly modest amounts of trans fats – enough to account for just 0.4% of total energy intake – were enough to raise the risk of depression by nearly 50%. They also found that olive oil had a protective effect.

At the start of the study, 12,059 volunteers – initially free from depression – had their diet, lifestyle and health recorded. During six years’ follow-up, 657 of them were newly diagnosed with depression.

Even after adjustment for relevant confounders, people who consumed more trans-fats “presented up to a 48% increase in the risk of depression when they were compared to participants who did not consume these fats,” said the authors. They found a clear dose-response relationship, “whereby the more trans-fats were consumed, the greater the harmful effect they produced in the volunteers,” they added.

When they looked at the relationship between depression and participants’ consumption of polyunsaturated fats and of monounsaturated fats, they found that these had a beneficial effect, in reducing the risk of depression.

The authors say that their findings help to explain the higher incidence of depression in northern European countries compared with countries in which a Mediterranean diet is most common. They suggest that increasing levels of depression in higher income countries are linked “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”.

The population studied had a low average intake of trans fats – energy from these fats accounted for just 0.4% of the volunteers’ total energy intake – and much of this came from natural foods such as whole milk and cheese. “Despite this,” say the authors, “we observed an increase in the risk of suffering depression of nearly 50%.”

The authors point out that the significance of their results “might be really important in other settings such as the American population where TFA intake is by far higher (up to 2.5% of total energy intake) and in which the main sources of TFA are artificial foods”.

An accompanying analysis suggests that depression and cardiovascular disease seem to be similarly affected by diet, and that similar mechanisms might lie behind the effect of trans fats on both.

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