Trans fat worse than anticipated

The "apple' body shape that increases the risk of diabetes and heart disease may be accelerated by eating trans fat, according to new animal research at Wake Forest University School of Medicine.

"Diets rich in trans fat cause a redistribution of fat tissue into the abdomen and lead to a higher body weight even when the total dietary calories are controlled," said Lawrence L Rudel, PhD, professor of pathology and biochemistry and head of the Lipid Sciences Research Program.

"What it says is that trans fat is worse than anticipated," Rudel said. "I was surprised."

According to the FDA, trans fat is found in vegetable shortenings, some margarines, crackers, cookies, snack foods, and other foods made with or fried in partially hydrogenated oils. Unlike other fats, the majority of trans fat is formed when food manufacturers turn liquid oils into solid fats like shortening and hard margarine by adding hydrogen.

Kylie Kavanagh, DVM, presented the findings last week at the 66th annual Scientific Sessions of the American Diabetes Association in Washington, DC. She said that over six years, male monkeys that were fed a western-style diet that contains trans fat had a 7.2% increase in body weight, compared to a 1.8% increase in monkeys that ate monounsaturated fats, such as olive oil.

All that extra weight went to the abdomen, and some other body fat was redistributed to the abdomen. Computed tomography (CT) scans showed that the monkeys on the diet containing trans fats had dramatically more abdominal fat than the monkeys on the monounsaturated fat. "We measured the volume of fat using CT," Kavanagh said. "They deposited 30% more fat in their abdomen."

The monkeys were all given the same amount of daily calories, with 35% of the calories coming from fat. The amount of calories they got should only have been enough to maintain their weight, not increase it, Rudel said. "We believed they couldn't get obese because we did not give them enough calories to get fat."

"We conclude that in equivalent diets, trans fatty acid consumption increases weight gain," said Kavanagh.

Kavanagh said the six-year length of the study was equivalent to 20 years in people.

Other researchers on the American Diabetes Society report include Janice D. Wagner, PhD, DVM, John Jeffrey Carr, MD, Kate Jones, BS, Janet Sawyer, MS, and Kathryn Kelly., BS, all from Wake Forest University School of Medicine.