Trans fats aren't good if you're trying to keep your waistline under control, as is generally agreed -- but it may not be doing your memory any good either.

In a study presented at the American Heart Association conference in Chicago, researchers said trans fat, utilized for decades to make margarine and found in many foods like crackers and cookies to increase their shelf life, may be damaging to a person's memory.

"Trans fats increase the shelf life of the food but reduce the shelf life of the person," says Dr. Beatrice Golomb of the University of California, San Diego School of Medicine.

Previous studies have indicated associations between consumption of trans fat and heart disease, diabetes, obesity and even aggression.

"They're a metabolic poison and that's not a good thing to be putting into your body," Golomb, author of the study, adds. "They don't provide anything the body needs."

In the study, around 1,000 healthy men of working age were shown a series of words on cards, and quizzed as to whether a word was new or whether it had been shown to them before.

The researchers say a significant number of the men who had a lot of trans fat in their system, as determined by blood tests, remembered fewer repeated words than those men with less in their system.

The study of healthy, younger men echoes findings in previous studies that showed trans fat levels' effect on memory in older women and in a small number of younger women.

While the study cannot prove a direct cause and effect connection, many experts suspect the consumption of excess amounts of trans fat may cause a type of cell damage known as oxidative stress.

"These artificial fats penetrate every cell in the body and can disrupt basic cell functions," says Dr. Walter Willett, head of the department of nutrition at the Harvard School of Public Health. He was not involved in Golomb's research.

The American Heart Association says Americans should consume no more than 2 grams of trans fat daily, an amount already naturally present in dairy and meat products most people typically eat.

The problem of excess trans fat generally raises its head when people consume significant amounts of processed food, experts say.

As part of an effort to reduce amounts of trans fat in American diets, the FDA in 2006 required that manufacturers include the amount of trans fat on informational nutrition labels on their products.