The Link Between Daily Consumption of Diet Soda and Development of Metabolic Syndrome and Type 2 Diabetes (Medscape Today)
A few of my patients would like to know more about the recent study published in Diabetes Care, concerning the link between daily consumption of diet soda and the development of metabolic syndrome and type 2 diabetes. What was the outcome of this study, and should I be warning my patients?
|Response from Teresa L. Pearson, MS, RN|
Director, Diabetes Care, Fairview Health Services, Minneapolis, Minnesota
Some recent studies have left many of us wondering about the consumption of our favorite diet soda. Although we all probably have assumed that drinking too much regular soda will increase our risk for heart disease, diabetes, and metabolic syndrome due to the extra calories, the findings that diet soda might be directly linked to these diseases are somewhat surprising. In 2007, a study published in the July 31 issue of the journal Circulation reported just such a link. A total of 3500 participants of the Framingham Offspring Study were asked about their dietary habits, including their consumption of soda, during 3 exam periods over the course of the study. Drinking ≥ 1 soda a day was linked with a 44% higher risk of developing metabolic syndrome, compared with drinking < 1 soda a day. The researchers concluded that it is unclear whether this link is a causative effect or possibly an indicator of less healthy habits, such as eating higher-fat foods, smoking, and exercising less.
In the multicenter Atherosclerosis Risk in Communities (ARIC) study, 9514 middle-aged adults were assessed for dietary intake, both at the beginning of the study and 6 years later, by employing a 66-item food frequency questionnaire. Patient follow-up 9 years later demonstrated that nearly 40% of the study’s participants had developed metabolic syndrome. The researchers concluded that diet soda is strongly associated with an increased risk for metabolic syndrome, whereas — surprisingly — sweetened beverages, such as juices and regular soda, are not. This new analysis of ARIC data appeared in the February 19, 2008 issue of Circulation. As with the Framingham Offspring Study, the researchers indicated that these findings are not conclusive but offer a possible explanation, similar to findings in rodents, suggesting that artificial sweeteners may lead to increased intake of the beverage because they may interfere with the body’s ability to properly assess caloric intake, leading to overeating.
Of interest, a third study, the Multi-Ethnic Study of Atherosclerosis (MESA), reported similar findings in Diabetes Care earlier this year. Whereas the first 2 studies suggested that the link to diet soda is only incidental, the goal of this study was to evaluate the associations between diet soda consumption and the risk for incident metabolic syndrome and type 2 diabetes. MESA was based on a population-based sample of 6800 men and women aged 45-84 years (38% white, 28% black, 23% Hispanic, and 11% Asian [of Chinese descent]), selected from 6 US field centers. Patients who drank diet soda at least once a day had a 36% greater relative risk for incident metabolic syndrome and a 67% greater relative risk for incident type 2 diabetes vs nondiet soda drinkers. The researchers cautioned that these observational data cannot establish causality.
The study authors stated that these results appear to corroborate the findings from the ARIC and Framingham studies indicating that consumption of diet soda, either independently or in conjunction with other dietary and lifestyle behaviors, may lead to metabolic syndrome or type 2 diabetes.
Therefore, what do these studies tell us? They all have limitations: They are observational in design, precluding determination of causality. Thus, it appears that the jury is still out on a causative relationship between diet soda and metabolic syndrome or type 2 diabetes. However, there may be a link between people who drink diet soda and metabolic syndrome or type 2 diabetes due to the less than healthy behaviors in other areas, such as lack of exercise, eating high-fat foods, or eating larger portions — all of which need further investigation. Experts, including the American Heart Association (AHA), believe that heart disease has many risk factors, and there’s not enough evidence to directly blame diet soda intake. More research is needed on the role of soda before formal recommendations can be made. Until then, the AHA views diet soda as “a good option to replace caloric beverages that do not contain important vitamins and minerals.” Furthermore, diet soda as well as water and fat-free or low-fat milk are better choices than full-calorie soft drinks.
This activity is supported by an independent educational grant from Novo Nordisk.