TJ North

No safe diet haven

JULIE STEENHUYSEN

Reuters

July 24, 2007 at 8:57 AM EDT

CHICAGO — Soft drinks – even diet ones – may be linked with increased risk factors for heart disease and diabetes, U.S. researchers say.

They found that adults who drink one or more soft drinks a day had about a 50-per-cent higher risk of metabolic syndrome – a cluster of risk factors such as excessive fat around the waist, low levels of “good” cholesterol, high blood pressure and other symptoms.

“When you have metabolic syndrome, your risk of developing heart disease or stroke doubles. You also have a risk of developing diabetes,” said Dr. Ramachandran Vasan of Boston University School of Medicine, whose work appears in the journal Circulation.

Previous studies have linked consumption of sugar-laden soft drinks with multiple risk factors for heart disease, but Dr. Vasan and his colleagues also found the link extends to diet sodas.

The study included about 6,000 middle-aged men and women who were observed over four years.

Those who drank one or more soft drinks a day had a 31-per-cent greater risk of becoming obese.

They had a 30-per-cent increased risk of developing increased waist circumference – which has been shown to predict heart disease risk better than weight alone.

They also had a 25-per-cent higher risk of developing high blood triglycerides as well as high blood sugar, and a 32-per-cent higher risk of having low levels of high-density lipoprotein – so-called good cholesterol.

The researchers then analyzed a smaller sample of participants on whom data on regular and diet soft-drink consumption were available. Those who drank one or more diet or regular soft drinks a day had a 50-to-60-per-cent increased risk for developing metabolic syndrome.

Intriguing new angle

“The part about diet soda is more intriguing,” Dr. Vasan said.

He said people who drink soft drinks, whether diet or sugar-sweetened, tend to have similar dietary patterns.

“On average, soda drinkers tend to eat more calories, consume more saturated fat and trans fat, eat less fiber, exercise less and be more sedentary,” Dr. Vasan said in a telephone interview.

The researchers adjusted for those factors and still observed a significant link between soft drink consumption and the risk of developing metabolic syndrome.

He said there are several theories about how diet soft drinks could increase a person’s metabolic risk.

“One possibility is that diet soda is sweet. Maybe drinking something sweet conditions you in such a way that you develop a preference for sweet things,” he said. “Also, diet soda is a liquid. When you take liquids at a meal, they don’t satiate you as much (as solids).”

The caramel colouring of some sodas also may play a role. He said caramel colouring in animal experiments was associated with tissue inflammation.

“These are all theories which we have not studied,” Dr. Vasan said.