Fast-Food Fats Prove Health Hazard
The dangers of trans-fatty acids—a cornerstone of fast-food cooking—were confirmed in June, when a study at Wake Forest University in Winston-Salem, North Carolina, revealed that even small daily amounts of trans fats led to alarming patterns of weight gain, atherosclerosis, and insulin resistance in monkeys.
Trans fats are the partially hydrogenated vegetable oils in the fryers at most fast-food chains; they are also used in many commercial cookies, pies, and crackers. These fats are commercially popular because they are shelf-stable and resistant to high heat. In recent years, though, they've become public health enemy number one, as evidence mounted that they contribute to heart disease, high cholesterol, and type 2 diabetes. In early 2006 new Food and Drug Administration rules went into effect requiring food labels to show trans fat content; in September the city of New York proposed severely limiting the use of trans fats in local restaurants.
Led by biochemist and pathologist Lawrence Rudel, the Wake Forest study set out to document the effects of a high trans-fat diet on atherosclerosis. But the results showed an impact far beyond hardened arteries. Two groups of male vervet monkeys were fed on different regimens for six years. Although the total calories and total dietary fat were the same for each group, the type of fat was not. One group received trans fats; the other received traditional monounsaturated fats. Over the six years, monkeys on the trans-fat diet added an average of 7.2 percent of their body mass, while the other group averaged just a 1.8 percent increase. Worse, the new weight from trans fats showed up mostly around the abdomen, a pattern strongly associated with cardiovascular disease in humans.
Ominously, the obesity-inducing monkey grub was not so different from a mainstream American diet. "The trans-fatty acids were roughly 8 percent of total energy," Rudel says. "That's high, but not outside the reported range for people who eat a lot of french fries and Krispy Kremes."
Commenting in the New England Journal of Medicine, Walter Willett, a nutritional epidemiologist at the Harvard School of Public Health, proclaimed that trans fats are probably a bigger public health problem than either food contamination or pesticides. Biochemists don't know exactly why they are so damaging, but the monkey study has one clear implication, Willett wrote: "Trans fats are clearly toxic to humans and have no place in human diets." Kathleen McGowan
From: Discover Magazine January 2007 http://www.discover.com/issues/jan-07/features/medicine/