Boston – People who drank one or more diet soda a day developed the same risks for heart disease as those who downed sugary regular soda, a large but inconclusive study found.
The results surprised researchers who expected to see a difference between regular and diet soda drinkers. It could be, they suggest, that even no-calorie sweet drinks increase the craving for more sweets, and that people who indulge in sodas probably have less healthy diets overall.
The study’s senior author, Dr. Vasan Ramachandran of Boston University School of Medicine, emphasized that the findings don’t show diet sodas are a cause of increased heart disease risks. But he said they show a surprising link that must be studied.
However, a nutrition expert dismissed the study’s findings on diet soda drinkers.
“There’s too much contradictory evidence that shows that diet beverages are healthier for you in terms of losing weight that I would not put any credence to the result on the diet (drinks),” said Barry Popkin, of the University of North Carolina at Chapel Hill, who has called for cigarette-style surgeon general warnings about the negative health effects of soda.
Susan Neely, president of the American Beverage Association, said the notion that diet drinks are associated with bulging waistlines defies common sense.
“How can something with zero calories that’s 99 percent water with a little flavoring in it … cause weight gain?” she said.
The research comes from a massive, multigenerational heart study following residents of Framingham, Mass. The new study of 9,000 observations of middle-aged men and women was published Monday online in the journal Circulation.
The researchers found those who drank one or more soda per day – diet or regular – had an increased risk of metabolic syndrome, compared with those who drank less than one soda.
Metabolic syndrome is a cluster of symptoms that increase the risk for heart disease including large waistlines and higher levels of blood pressure, blood sugar, cholesterol and blood fats called triglycerides.
At the start of the study, those who reported drinking one or more soft drink a day had a 48 percent increased prevalence of metabolic syndrome compared with those who drank less soda.
Of participants who initially showed no signs of metabolic syndrome, those who drank one or more soda per day were at 44 percent higher risk of developing it four years later, they reported.
Researchers were surprised when results did not differ between regular and diet soda drinkers, Vasan said.
But Popkin said that result isn’t that surprising. He said much of the market for diet sodas are people who have unhealthy lifestyles and know they need to lose weight. That means many people drinking diet sodas have unhealthy habits that could lead to increased heart disease risks, whether they drink diet soda or not.
Another possible reason is a theory called “dietary compensation,” which holds that if someone drinks a large amount of liquids at a meal, they aren’t satisfied and will tend to eat more at the next meal, Vasan said.
Another theory is that the substance that gives soda its caramel color promotes resistance to insulin, which is needed to process calories.
