A new analysis of data from the Framingham Heart Study, published in the journal Circulation, finds that people who drink soda every day are especially prone to "metabolic syndrome," a condition that includes high blood sugar, elevated triglycerides, extra abdominal fat, and low levels of HDL cholesterol (the "good" kind). Metabolic syndrome, in turn, is associated with a 100 percent increase in the risk of heart attack or stroke. But here's the weird thing about the study: It made hardly any difference whether the subjects drank regular or diet soda. The fact that neither the calories nor the high-fructose corn syrup mattered suggests that soda drinking is a proxy for other behaviors (or characteristics) that contribute to metabolic syndrome.
The researchers say the association between soda consumption and metabolic syndrome remained significant after they "adjusted for saturated fat and trans fat intake, dietary fiber consumption, smoking, and physical activity." But they concede "it is conceivable...that there may be residual confounding caused by lifestyle factors not adjusted for in the present analyses." At least as important, they do not suggest a plausible biological reason why drinking bubbly water containing a bit of flavor and artificial sweetener would affect blood sugar, triglycerides, cholesterol, and waistlines. The study nonetheless generated predictable headlines suggesting that Diet Coke or Fresca might give you a heart attack:
"Regular Soft Drink Consumption May Increase Heart Attack Risk" (India's Economic Times)
"Diet Sodas Are Bad for Your Health" (Times of India)
"Heart Risk of Diet Soda Found Equal" (Chicago Tribune)
"Diet or Regular, Soft Drinks Hurt Your Heart" (HeartZine)
"Diet Drinkers Also Face Risks" (Cincinati Enquirer)
"Study: Soda Increases Risk of Heart Disease" (CBS 13)
"No Safe Diet Haven" (Globe and Mail)
"Daily Soft Drink Hikes Risk for Heart Disease, Study Finds" (San Francisco Chronicle)
And so on.
Several news organizations, including Bloomberg and ABC News, did a better job of accurately reporting the study's findings and the controversy over their meaning. And to its credit, the American Heart Association, which publishes Circulation, issued a statement noting that the study "does not show that soft drinks cause risk factors for heart disease." It adds: "Diet soda can be a good option to replace caloric beverages that do not contain important vitamins and minerals. The American Heart Association supports dietary patterns that include low-calorie beverages like water, diet soft drinks, and fat-free or low-fat milk as better choices than full calorie soft drinks." If anything, the Circulation study should be welcomed by the soft drink industry, since it casts doubt on the claim that the extra calories (or the HFCS) in regular soda play a special role in obesity.