Burgers, Fries, and Diet Soda Are Recipe for Metabolic Syndrome

By Peggy Peck
MINNEAPOLIS, Jan. 22 -- Middle-age adults who regularly eat a double burger, fries, and a diet soda for lunch or dinner increase their risk of incident metabolic syndrome by 25% compared with those who limit red meat to two servings a week. But eating healthy doesn't reduce the odds of developing metabolic syndrome, said Lyn M. Steffen, Ph.D., M.P.H., R.D., of the University of Minnesota, who studied the eating habits of more than 9,514 middle-age Americans. After nine years of follow-up, 3,782 of the participants in the Atherosclerosis Risk in Communities study had three or more of the risk factors that are used to define metabolic syndrome, Dr. Steffen and colleagues reported online in Circulation, Journal of the American Heart Association.
Unlike other studies that have investigated relationships between nutrients and cardiovascular risk, "we specifically studied food intake, since when we start to think about making recommendations it is easier to do so using the framework of real foods, eaten by real people," Dr. Steffen said.
The researchers assessed food intake using a 66-item food frequency questionnaire administered at three-year intervals. From the responses to those questions, they were able to categorize people into a Western-pattern diet or a prudent-pattern diet.
A Western diet contained high amounts of refined grains, processed meat, fried foods, red meat, eggs, and soda with little consumption of low-fat dairy products, fruits, and vegetables.
Prudent eating patterns, by contrast, favored cruciferous vegetables, carotinoid vegetables, fruit, fish and seafood, poultry, and whole grains, along with low-fat dairy products.
At baseline from 1987 through 1989, the study participants were between 45 and 64 years old, a population at risk for weight gain, which is associated with metabolic syndrome.
"After adjusting for demographic factors, smoking, physical activity, and energy intake, consumption of a Western dietary pattern (Ptrend≤0.03) was adversely associated with incident [metabolic syndrome]," the researchers found.
When they analyzed the results by specific foods, they found that meat (Ptrend <0.001), fried foods (Ptrend=0.02), and diet soda (Ptrend≤0.001) were all significantly associated with increased risk of metabolic syndrome, but consumption of dairy products -- especially yogurt and low-fat milk -- was beneficial (Ptrend=0.006).
Regular soda, which Dr. Steffen said was expected to increase risk of metabolic syndrome, was not associated with increased risk.
Dr. Steffen said the soda findings might reflect poorer glycemic control, which has been reported in other studies of diet sodas. Moreover, she said a study in rats suggested that the consumption of artificial sweeteners "impairs the body's ability to predict the caloric content of foods, and may lead to increased intake and body weight."
Dr. Steffen said the association between a Western-type diet and metabolic syndrome, although expected, was nonetheless striking for some individual foods.
"For example, we looked specifically at french fries and found that eating one serving a day increased the risk of developing incident metabolic syndrome by 10%," she said in an interview.
An unexpected finding was that consuming a prudent diet (i.e. one that had a high concentration of fruits, vegetables, whole grains) and low-fat dairy products did not reduce the risk of metabolic syndrome. "We had expected to see a benefit because we have seen a beneficial relationship in other studies," she said.
The researchers noted that their study was limited by its use of a questionnaire to calculate food intake, which may have allowed for reporting bias as well as misclassification of some foods. For example, the questionnaire was "not designed to differentiate whole grain from refined grain items in the food list," they wrote.
The study was funded by the National Heart, Lung, and Blood Institute.
Dr. Steffen and colleagues reported no financial disclosures.
Primary source: Circulation, Journal of the American Heart AssociationSource reference:Lutsey PL, et al "Dietary intake and the development of the metabolic syndrome: the ARIC study" Circulation 2008; DOI: 10.1161/CIRCULATIONAHA.107.716159.