"Trans fats were most strongly linked to worse memory in men during their high-productivity years," author Dr. Beatrice A. Golomb, a professor of medicine at the University of California, San Diego School of Medicine, said in a statement.
On average, men ages 45 and younger in the study were able to recall 86 words, but with each additional gram of trans fat consumed daily, their memory performance dropped by 0.76 words. This drop translates into 21 fewer words recalled by the men in the study who consumed the most trans fat (about 28 grams per day), compared with the men who ate the least. "That's a pretty sizeable effect," Golomb told Live .
The researchers focused on the link between trans fat and memory in men ages 45 and younger because the number of women in the study in the same age group was too small to draw conclusions about whether the link held true for them as well.
The link between trans fat consumption and memory was not observed in people older than 45, the researchers said. Injuries to the brain accrue with age, which may make it tough to distinguish the effects of diet on memory, they said.
Previous has linked the consumption of trans fat to a number of negative effects on people's metabolism, levels of blood fat and inflammation, and cardiac and general health. Moreover, studies have shown that trans fat consumption may be related to behavioral and mood problems, Golomb said.
Foods that contain trans fat include baked goods (cookies and cakes), ready-to-use frostings, fried food and snacks such as potato chips and microwave popcorn, according to the FDA.
The exact mechanism of how trans fat may affect memory is not clear. One possible explanation is that trans fat act as a stressor on cells, which could affect memory and cognitive function, Golomb said.
Trans fat also promotes inflammation, which has been shown to contribute to memory problems. For example, "Alzheimer's is considered an inflammatory brain condition," Golomb said.
A third possible mechanism is that trans fat inhibits the production of molecules called long-chain omega-3 fatty acids, which the body makes from the short-chain omega-3 fatty acids that people eat when they consume plants such as flax. "And the long-chain ones are the ones that the brain actually needs," Golomb said. Moreover, omega-3s are anti-inflammatory, she said.
The new study was published today (June 17) in the journal PLOS ONE.