French fries cooked in hydrogenated oils are a big source of trans fat.

For a decade, HSPH researchers have publicly warned about the health risks of eating trans fatty acids, found in many processed and fried foods. Now, a restaurant chain synonymous with fast food, McDonald’s, has announced plans to reduce levels of trans fatty acids in French fries by nearly half and to reduce levels of saturated fats by 16 percent. McDonald’s is the first major chain of fast food restaurants in the US to do so.

"I don’t want to shoot the first horse out of the blocks," said Eric Rimm, an associate professor in the Departments of Epidemiology and Nutrition, "but what took them so long?"

Trans fatty acids raise levels of bad cholesterol while lowering levels of good cholesterol. The fat is found in partially hydrogenated vegetable oils that help extend the shelf life of foods such as margarine; processed cookies, crackers, and cake; frozen foods; and some cereals. Foods fried in hydrogenated oils–such as French fries–also contain trans fat.

Trans fat occurs naturally at low levels in some dairy products and meats.

Both Walter Willett, chair of the Department of Nutrition, and Rimm welcomed the McDonald’s announcement–while recognizing that much more needs to be done to minimize trans fatty acids in Americans’ diets.

"The announcement is a good start, but even a 50 percent reduction in the amount of trans fat in French fries leaves a lot of trans fat remaining," said Rimm.

Said Willett: "It’s an important step in the right direction. A lot of people who eat at McDonald’s will now be eating food that is less bad for them, so we should see a direct health effect from that. But also, an indirect health effect may be that more people become aware of trans fat."

Eric Rimm

"There is absolutely no known benefit to eating trans fat," said Rimm.

Willett said that he and a small group of other researchers started to detect health problems related to eating trans fat through the Nurses’ Health Study (NHS) in the early 1990s; Willett is a senior investigator on the study. Other studies suggested similar findings. Subsequent NHS research linked eating trans fat to an increased risk for both heart disease and Type 2 diabetes. As a result, Willett and his colleagues began raising a warning cry about trans fat.

Rimm served on an Institute of Medicine panel that issued a damning report on trans fat last July, saying that trans fatty acid consumption should be as low as possible.

"The report provides a message that national agencies, food producers, and the lay public should now accept: ‘Senior scientists from across the country with a range of technical expertise have reviewed the available evidence and have concluded that trans fat is bad for your health’," said Rimm.

	Walter Willett

"It has been a disappointingly slow process," said Willett, "but the FDA has now committed itself to making this happen. Without the labeling, consumers really have a hard time figuring out how much trans fat is in a food."

Said Rimm: "I hope the labeling will create an effect where there is less demand for foods with trans fat, and then companies will become more creative about providing healthier food."

Both Willett and Rimm said that they hoped the McDonald’s announcement will prompt other companies to reduce or eliminate trans fat in their foods.