Downing a big fast-food breakfast may spur a temporary but large inflammatory response in the blood vessels, a small study suggests.

Researchers say that while an occasional indulgence in such high-fat, high-carbohydrate fare probably poses no concern, the new findings suggest that making it a regular routine could lead to chronic blood vessel inflammation and complications, such as heart attack and stroke.

The study included nine healthy, normal-weight adults who were fed a breakfast of one Egg McMuffin, a Sausage McMuffin and two servings of hash browns from McDonald’s. The meal weighed in at 910 calories, 81 grams of carbohydrates, 51 grams of fat and 32 grams of protein.

While the hearty breakfast may be on the supersize side, lead study author Dr. Ahmad Aljada of the State University of New York at Buffalo said it reflects what many Americans order up at fast-food restaurants.

“We wanted to look at a typical American meal,” he told Reuters Health. “We’re not targeting McDonald’s.”

Dr. Catherine Adams, corporate vice president of worldwide quality at McDonald’s and a registered dietitian, cautioned against reading too much into the findings.

The normal metabolic response to eating involves some inflammation and the production of molecules called oxygen free radicals. Any heavy meal, compared with water, will generate a much greater inflammatory response, Adams noted.

And no one, she told Reuters Health, advocates regularly consuming a 900-calorie fast-food breakfast.

However, Aljada said additional research suggests that it’s not the size, but the content of the breakfast that may be the problem when it comes to inflammation in the blood vessels.

He said he and his colleagues found that 900 calories’ worth of an American Heart Association (AHA)-endorsed breakfast high in fruit and fiber did not produce the inflammatory responses seen with the fast-food breakfast.

“The number of calories is not the issue,” Aljada said. “It’s the type of food.”

There may be something about the metabolism of fat, for example, that spurs significant inflammation, according to the researcher.

In past studies, he and his colleagues found that both pure glucose (sugar) and fat trigger greater inflammatory responses than protein does. The AHA-based breakfast, while high in carbohydrates, contains complex, fiber-rich carbs, as well as antioxidant vitamins that may ward off inflammation, Aljada explained.

For the new study, the researchers gave nine adults the fast-food breakfast and another eight a glass of water after an overnight fast. They took blood samples before the meal or drink, then again one, two and three hours afterward.

The blood samples showed that in the fast-food diners, markers of inflammation and free-radical production rose and remained high for hours after the meal.

Chronic inflammation is key in the development of the artery disease atherosclerosis, a hardening and narrowing of the arteries that can lead to heart attack and stroke. Aljada said that the concern is that, over time, repeated inflammatory responses like those seen in the study could lead to chronic inflammation in the blood vessels.

He said his advice to fast-food fans is to “eat moderately.”

“And,” the researcher added, “you may want to look into eating more fruit and fiber.”

Adams echoed the call for moderation, saying fast-food fare can fit into a balanced diet. Ordering that Egg McMuffin with a glass of orange juice-rich in free radical-squelching antioxidants is one way to strive for better balance, she noted.

Aljada said he and his colleagues are studying the inflammatory effects of other types of food as well, including Atkins-style high-fat, high-protein meals, and foods with a high glycemic index. Foods in this latter group are digested quickly to glucose and cause a swift surge in blood sugar; they include carbohydrates such as white bread and potatoes.

SOURCE: American Journal of Clinical Nutrition, April 2004.