Eating trans fats may increase irritability and aggression, a new study suggests.

"This study provides the first evidence linking dietary trans fatty acids with behavioural irritability and aggression," concludes the study by Dr. Beatrice Golomb of the University of California, San Diego School of Medicine, and her colleagues.

In the U.S., defence lawyers have used the so-called Twinkie defence to argue a defendant's behaviour, such as switching from a health-conscious diet to scarfing down Twinkies and other junk food, to show untreated depression had diminished an accused's capacity to tell right from wrong.

Golomb and her co-authors analyzed diet surveys of 945 men and women with an average age of 57 in the U.S. and did behavioural assessments on them for the study, published in the journal PLoS ONE, a peer-reviewed online publication published by the non-profit Public Library of Science (PLoS).

The researchers scored participants on factors such as:

  • A history of aggression.
  • How they handled conflict.
  • How they self-rated impatience and irritability levels.

Eating more trans fats was significantly associated with repercussions for others after taking factors including education, smoking and alcohol use into account, the researchers said.

"If the association between trans fats and aggressive behaviour 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.

Trans fats result when hydrogen is added to vegetable oil to make foods last longer on the shelf.

Previous research has shown a diet high in trans fat increases "bad" (LDL) cholesterol levels and lowers "good" (HDL) cholesterol. In the study, none of the participants was taking cholesterol medications or had high levels of bad cholesterol.