TUESDAY, Jan. 22, 2008 (HealthDay News) -- A "Western" diet heavy in meat, fried foods and refined grains puts people at higher risk of developing metabolic syndrome, the collection of risk factors for heart problems, stroke and type 2 diabetes, a new study found.
The findings confirmed previous research with one interesting twist: Drinking diet soda won't change the health-risk equation (surprisingly, it ups the risk, too), although consuming more dairy might protect you.
A whopping 60.5 percent of the study participants either had metabolic syndrome at the start of the study or developed it during nine years of follow-up.
"This is a red-alert wake-up call," said Dr. Suzanne Steinbaum, director of Women and Heart Disease at Lenox Hill Hospital in New York City, who was not involved with the study. "I love that they call this a Western diet. It's the perspective that we, as Americans, cannot eat any worse."
The findings were published in the Jan. 22 issue of Circulation.
A person is thought to have metabolic syndrome if he or she has three or more of the following cardiovascular risk factors: large waist circumference, high blood pressure, high fasting glucose levels, low HDL ("good") cholesterol levels and high triglycerides.
According to U.S. government data collected between 1988 and 1994, 24 percent of adult Americans (47 million people) had metabolic syndrome. That number is probably higher now, the study authors stated.
Although obesity and physical inactivity underlie most cases of metabolic syndrome, the role of diet is still not well understood.
The authors of the new study relied on "food frequency" questionnaires that had been filled out by almost 10,000 people participating in the government-sponsored Atherosclerosis Risk in Communities study. The questionnaire included 66 items related to food consumption.
Participants' dietary preferences were categorized as either "Western-pattern" or "prudent-pattern," depending on the overall responses.
The Western diet consisted of more refined grains, processed meat, fried food, red meat, eggs and soda, and less fish, fruit, vegetables and whole grains.
The prudent diet was heavy on cruciferous vegetables such as broccoli and cabbage; carotenoid vegetables (carrots, pumpkins); fruit; fish and seafood; poultry; whole grains; and low-fat dairy.
The association involving metabolic syndrome with certain specific food items -- such as fried foods, regular and diet soda, fruit drinks, nuts and coffee -- was also explored.
People with the highest scores in the "Western-pattern" diet had an 18 percent increased risk of developing metabolic syndrome, compared with those with the lowest scores in this group.
Individuals with the highest consumption of meat had a 26 percent greater risk of developing metabolic syndrome, compared with those who ate the least amount of meat. Hamburgers, hot dogs and processed meats seemed to accelerate the effect.
On the other hand, eating dairy was found to be protective: Individuals consuming the most dairy had a 13 percent lower risk of developing metabolic syndrome, compared to those who consumed the least.
Fried foods -- i.e., fast foods -- and diet soda were also associated with metabolic syndrome, while sweetened beverages -- soda and fruit drinks -- as well as coffee and nuts were not.
The diet soda findings echo those from a previous trial, the study authors said.
"The first time this came up, we didn't believe it," Steinbaum said. "Take two, and it's now part of another large study."
"We did not expect to find that," added study co-author Lyn Steffen, an associate professor of epidemiology at the University of Minnesota School of Public Health. "I don't know why that is, but I think there is some basic science under way now looking at diet soda and just what it does to promote these metabolic abnormalities."
"The message hasn't changed," Steffen added. "People should eat according to the dietary guidelines for Americans, which is a diet rich in plant foods. I don't oppose meat, but they should consume red and processed meat once or twice a week, not once or twice a day."
Read more about metabolic syndrome at the American Heart Association.