This year, Diet Coke is sponsoring The Heart Truth, a 10-city nationwide road show created in 2002 by the National Heart, Lung, and Blood Institute (NHLBI) to promote heart disease awareness among women.

The show is making its first stop this weekend at St. Paul's Maplewood Mall.

At the event, you can ogle several one-of-a-kind red dresses previously worn by such celebrities as Heidi Klum, Jenna Fischer, Lisa Rinna and Vanessa Williams. (The red dress is to heart disease what the pink ribbon is to breast cancer.)

You'll also be offered educational materials about heart disease and invited to take part in free body mass index, glucose, cholesterol and blood pressure screenings to help you assess your personal risk for developing the disease.

Those tests are important. And women need to be educated about their leading killer, heart disease.

But nowhere in The Heart Truth's educational materials are you going to find mentioned what has become a red-hot topic of discussion among heart disease researchers: the possible link between the consumption of both regular and diet sodas and metabolic syndrome, a cluster of conditions that can lead to heart disease, stroke and diabetes.

Two big studies
Using data from the large, ongoing Framingham Heart Study, scientists reported last July that people who daily downed one or more sodas — regular or diet — increased their risk of developing metabolic syndrome by 56 percent. (The components of metabolic syndrome include excess fat around the waist or abdomen, high blood pressure, and abnormal levels of blood sugar, triglycerides and HDL, or "good," cholesterol.)

That study, which appeared in the American Heart Association's journal, Circulation, caused a bit of a stir. Researchers already knew that sugary beverages increased the risk for metabolic syndrome. But calorie-free diet sodas? That was a puzzling — and unexpected — finding.

Then, late last month, a second Circulation study came up with similar results: A 34 percent increased risk for metabolic syndrome among people who drank diet soda daily — much higher than for regular soda.

"We were surprised," says Lyn M. Steffen, PhD, associate professor of epidemiology at the University of Minnesota and a co-author of the second study. "What we need to do now is try to explain why this is."

The missing link
The most likely explanation is that "people who drink diet soda have other behaviors that might promote the syndrome," says Steffen. Perhaps consumers of diet soda have less healthy diets than their non-diet-soda-drinking peers. Or maybe they're less physically active.

"Another explanation is that the artificial sweetener in the diet soda promotes weight gain and metabolic syndrome," says Steffen.

An animal study just published in the journal Behavioral Neuroscience seems to support that theory. It found a link between a no-calorie sweetener (saccharin) and weight gain. But this study was very small (27 rats) and contradicts the results of several human studies that found artificial sweeteners helpful for weight control.

Obviously, much more research is needed.

Take home message, not messenger

In the meantime, both women and men need to better understand their risk for heart disease — and how to lower that risk. Events like The Heart Truth can be good places to get started.

Just don't confuse the message with the messenger.

"We have research that shows that soda consumption can be an indicator of a lifestyle that causes heart disease," notes Allison Fisher, a writer/editor for NHLBI and a member of its press team.

"We're not promoting Diet Coke," she adds. "We're just partnering with them to reach women with our heart health message."

Related content

What: The Heart Truth Road Show
Where:  Maplewood Mall, 3001 White Bear Ave., St. Paul
When:  Feb. 15-17. 3-9 p.m. (Friday); noon-6 p.m. (Saturday and Sunday)