The results of the research weren't a surprise to the experts, but they say the findings reaffirm something that more people need to understand:
"What we put into our mouth makes a big difference in terms of our health," said Dr. Charles McCauley, a cardiologist with Marshfield Clinic in Wisconsin, who reviewed the research but wasn't involved with the study. "We really have to be very careful as to how our food is processed and what kind of ingredients we use."
In the study, at The Heart Research Institute in Sydney, Australia, 14 people, ages 18-40, ate two meals of carrot cake and a milkshake one month apart. One meal was high in saturated fat — using coconut oil — and the other was high in polyunsaturated fat — using safflower oil.
Saturated fat has long been linked to the buildup of plaque that can lead to heart attacks and strokes. HDL, the "good" cholesterol, protects arteries from the inflammation that leads to artery-clogging plaques. And plaque hurts the ability of arteries to expand to carry blood to tissues and organs.
The researchers, led by Dr. Stephen Nicholls, a cardiologist now at the Cleveland Clinic, found that three hours after eating the saturated-fat cake and shake, the lining of the arteries was hindered from expanding to increase blood flow. And after six hours, the anti-inflammatory qualities of the good cholesterol were reduced.
But the polyunsaturated meal seemed to improve those anti-inflammatory qualities. Also, fewer inflammatory agents were found in the arteries than before the meal.
"They're looking at things in terms of real live living," said McCauley. "Carrot cake. How more real does that get?"
The study appears in the Aug. 15 issue of the Journal of the American College of Cardiology.
"It's a simple study. Sometimes the best studies are those that are very straightforward," said Dr. Richard Milani, head of preventive cardiology at Ochsner Clinic Foundation in New Orleans.
He notes that the research isn't suggesting that people eat a steady diet of carrot cake and milkshakes.
However, he said, "given a choice between something with polyunsaturated fat and saturated fat, please avoid the saturated fat."
Nicholls said "the take-home, public-health message is this: It's further evidence to support the need to aggressively reduce the amount of saturated fat consumed in the diet."
Saturated fats are found mostly in food from animals, including beef, pork, lard, poultry fat, butter, milk and cheeses, and some plants, including coconut oil, palm oil and cocoa butter.
Polyunsaturated fats are found in oils from plants, including safflower, sesame and sunflower seeds, corn and soybeans, many nuts and seeds.
Dr. James O'Keefe, a cardiologist at the Mid America Heart Institute in Kansas City, said Nicholls' study shows "a really important concept — when you eat the wrong types of food, inflammation and damage to the vessels happens immediately afterward."
Too many people simply are eating the wrong kind of fats, O'Keefe said.
"Even one meal of a double cheeseburger with fries and a Coke will mess up your system, let alone a steady diet of it, which is recipe for disaster," O'Keefe said.