Most of us probably assume that if your only beverage choices were diet or regular soda, the diet variety would be better. After all, drinks made with non-nutritive sweeteners do give us fewer calories.
But recent studies indicate that drinking diet soda can lead to our gaining weight. They can raise the A1C levels of those of us who have diabetes. And drinking them is also associated with a greater risk of heart disease.
Participants in an eight-year study at the University of Texas Health Science Center, San Antonio, who drank several cans of diet soda every day were more likely to become overweight or obese than those who drank several regular sodas. Sharon P. Fowler, MPH, and her colleagues reported this finding in abstract 1058-P at the 2005 annual meeting of the American Diabetes Association in San Diego.
Another study, this one in the Annals of Epidemiology last year, found that adults with diabetes who drank one or more drinks of diet soda per day had A1C levels was 0.7 percent higher than those who drank none. That difference is about what we can expect when we start a good new diabetes medication and take it for a year.
Even more disturbing is a study this year in the American Heart Association's journal, Circulation. After tracking the health of more than 6,000 middle-aged adults, researchers found that those who drank one or more soft drinks - whether diet or regular - had an increased risk for metabolic syndrome compared with those who didn't drink as many. Metabolic syndrome is a cluster of risk factors for heart disease and diabetes, including high blood pressure, too much fat around the middle, and low levels of good cholesterol.
The soft drink industry primarily uses aspartame (brand name NutraSweet) in its diet drinks. Diet Rite is the biggest selling non-aspartame diet soda brand. It uses a combination of sucralose and acesulfame potassium.
How could these non-nutritive sweeteners possibly be associated with weight gain and the metabolic syndrome? The authors of the Circulation study led by Ravi Dhingra, MD, an instructor in medicine at Harvard Medical School, think that the high level of sweetness "may lead to conditioning for a greater preference for intake of sweetened items."
That's controversial. But an even more disturbing mechanism that the authors propose is that, "The caramel content of both regular and diet drinks may be a potential source of advanced glycation end products, which may promote insulin resistance and can be proinflammatory." I have written several times about the dangers of a high-AGE diet here, especially this article in April.
The American Beverage Association, which represents soft-drink companies, was quick to respond to the Circulation study. The organization's president, Susan Neely, maintains that, "it is scientifically implausible to suggest that diet soft drinks - a beverage that is 99 percent water - cause weight gain or elevated blood pressure."
Maybe that other 1 percent matters. And researchers may be more objective than lobbyists.
Even all of these studies together don't prove that diet soda or non-nutritive sweeteners actually is the cause of all of these troubles. They report on an association or correlation.
But the evidence against diet soda is mounting. All the more reason to consider other beverages. Like water.
Read what expert Heater Reese has to say about diabetics drinking soda and juice from her January 2, post.
Soft drinks and heart problems? Read this article to learn about the connection.