Medical Research: What is the background for this study? What are the main findings?
Dr. Hazuda: The long-term effects of diet soda consumption on health outcomes is unclear, and studies in both humans and animals have raised concerns about their potentially harmful health effects including weight gain and increased cardiometabolic risk. Most human studies have focused on middle-aged or younger adults, rather than focusing specifically on people 65 years and older, a rapidly growing segment of the U.S. population that has a disproportionately high burden of cardiometabolic disease and associated healthcare costs. Therefore, our study examined prospectively the association between diet soda intake and long-term change in waist circumference in a biethnic cohort of older (65+ years) Mexican American and European American participants in the San Antonio Longitudinal Study of Aging (SALSA).
SALSA included a baseline examination (1992 – 1996) and three follow-up examinations (2000-2001, 2001-2003, and 2003-2004). The total follow-up period averaged 9.4 years. Diet soda intake, waist circumference (WC), height and weight were measured at each examination along with sociodemographic factors, leisure physical activity, diabetes mellitus, smoking, and length of follow-up.
The main finding is that over the total 9.4-year SALSA follow-up period and after adjustment for multiple potential confounders, daily diet soda users (1+ diet sodas/day) experienced an increase in waist circumference of 3.2 inches, while occasional diet soda users (>.05 < 1 diet soda/day) experienced a waist circumference increase of 1.8 inches, and nonusers of diet soda experienced a WC increase of 0.8 inches. Thus, there was a striking dose-response relationship between chronic diet soda intake and long-term increases in waist circumference.
Medical Research: What should clinicians and patients take away from your report?
Dr. Hazuda: Waist circumference is an indicator of abdominal obesity, and large waist circumference, an important component of metabolic syndrome, is associated with greater cardiometabolic risk (i.e., risk of diabetes, cardiovascular disease, and stroke). The SALSA study shows that increasing diet soda intake was associated with increasing abdominal obesity, which may increase cardiometabolic risk in older adults. While our prospective observational study does not prove that there is a causal link between chronic diet soda intake and WC, together with accumulating evidence from both other human studies and animal studies, findings from the SALSA study should heighten both patients’ and clinicians’ awareness of the potential harmful health effects of diet soda consumption.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Hazuda: The most compelling evidence about possible adverse health effects of diet soda intake may come from research that can identify both the health outcomes of chronic diet soda intake and the mechanisms that link diet soda intake to these health outcomes. Mechanisms such as the dysregulation of sweet taste as a predictor of caloric consequences and a trigger for physiological responses that regulate energy balance; adverse effects on beneficial microflora in the gut that play a major role in body weight regulation;and adverse effects on leptin signaling that inhibits hunger and maintains energy balance are being studied in animal models. More intense study of these and other possible mechanisms in human populations is needed to support the accumulating findings from observational studies such as SALSA about the adverse health effects of diet sodas on cardiometabolic ris and other health outcomes.
MedicalResearch.com Interview with:, & Helen P. Hazuda, Ph.D. (2015). Diet Soda Linked To Increased Belly Fat and Waist Size MedicalResearch.com