Researchers from the University of California, San Diego School of Medicine are contending that  consumption of dietary trans fatty acids (dTFAs) is associated with irritability and aggression. 

Their survey of 945 men and women led them to link dTFAs with adverse behaviors that impacted others, ranging from impatience to overt aggression.  Dietary trans fatty acids are primarily products of hydrogenation, which makes unsaturated oils solid at room temperature. They are present at high levels in margarines, shortenings and prepared foods. Adverse health effects of dTFAs have been identified in lipid levels, metabolic function, insulin resistance, oxidation, inflammation, and cardiac health.

 The survey measured such factors as a life history of aggression, conflict tactics and self-rated impatience and irritability, as well as an "overt aggression" scale that tallies recent aggressive behaviors. Analyses were adjusted for self-reported sex, age, education, and use of alcohol or tobacco products.

The research was led by Beatrice Golomb, MD, PhD, associate professor in the UC San Diego Department of Medicine.

"We found that greater trans fatty acids were significantly associated with greater aggression, and were more consistently predictive of aggression and irritability, across the measures tested, than the other known aggression predictors that were assessed," said Golomb. "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."

Couldn't the reverse claim have been made since it was just a correlation in surveys?  That anger forced people to eat more trans fats?  Absolutely.

Citation: Golomb BA, Evans MA, White HL, Dimsdale JE (2012) Trans Fat Consumption and Aggression. PLoS ONE 7(3): e32175. doi:10.1371/journal.pone.0032175