Eating dietary trans fatty acids (dTFAs), typically referred to as unsaturated or trans fat is linked to bad behavior ranging from impatience to overt aggression, according to a new study.

Irritability and aggression can now be added to the long list of ill effects that have previously been linked to unsaturated fat consumption, like increased risk for coronary heart disease, obesity, diabetes, Alzheimer’s disease, cancer, liver dysfunction, infertility in women and major depressive disorder.

Researchers at University of California in San Diego analyzed surveys from 945 men and women about their history of aggression, conflict tactics, self-rated impatience, irritability, and overt aggression and adjusted for other factors such as sex, age, education, and use of alcohol or tobacco products.

They found that greater consumption of trans fatty acids were significantly associated with greater aggression, and that the level of unsaturated fat consumption was “consistently predictive of aggression and irritability, across the measures tested, than the other known aggression predictors that were assessed,” said lead researcher Dr. Beatrice Golomb, associate professor in the UC San Diego Department of Medicine, in a statement released on Monday.

Dietary unsaturated fats are rare in nature, but are found in many processed products of hydrogenation, and are solid at room temperature. They are found in high level in margarines, shortenings for frying and packaged and prepared foods like fast and snack foods.

Adverse health effects of these fats have been found in lipid levels, metabolic function, insulin resistance, oxidation, inflammation, and cardiac health.

The new study, published online in PLoS ONE, was the first that linked dTFAs with adverse behaviors that may impact others, and researchers said that the latest findings add to the list of reasons why these fats should be avoided.

"If the association between trans fats and aggressive behavior proves to be causal, this adds further rationale to recommendations to avoid eating trans fats, or including them in foods provided at institutions like schools and prisons, since the detrimental effects of trans fats may extend beyond the person who consumes them to affect others," Golomb said.

In 2002,a panel of experts from the National Academy of Sciences concluded that the only safe intake of trans fat is ‘zero,’ and because it would be impractical for people to eliminate all trans fat from their diet, the panel recommended that people consume as little of it as possible. 

The panel’s advice was supported by a 2006 New England Journal of Medicine scientific review that said “from a nutritional standpoint, the consumption of trans fatty acids results in considerable potential harm but no apparent benefit.”

The FDA issued a labeling rule requiring all manufacturers to list trans fat on the Nutrition Facts panel of foods and some dietary supplements, which became effective at the start of 2008.