Diet soda intake is associated with long-term increases in waist circumference in a biethnic cohort of older adults: the San Antonio Longitudinal Study of Aging

Abstract

Objectives: To examine the relationship between diet soda (DS) intake (DSI) and long-term waist circumference (WC) change (ΔWC) in the biethnic San Antonio Longitudinal Study of Aging (SALSA).

Design: Prospective cohort study.

Setting: San Antonio, Texas, neighborhoods.

Participants: SALSA examined 749 Mexican-American and European-American individuals aged 65 and older at baseline (baseline, 1992-96); 474 (79.1%) survivors completed follow-up 1 (FU1, 2000-01), 413 (73.4%) completed FU2 (2001-03), and 375 (71.0%) completed FU3 (2003-04). Participants completed a mean of 2.64 follow-up intervals, for 9.4 total follow-up years.

Measurements: DSI, WC, height, and weight were measured at outset and at the conclusion of each interval: baseline, FU1, FU2, and FU3.

Results: Adjusted for initial WC, demographic characteristics, physical activity, diabetes mellitus, and smoking, mean interval ΔWC of DS users (2.11 cm, 95% confidence interval (CI) = 1.45-2.76 cm) was almost triple that of nonusers (0.77 cm, 95% CI = 0.29-1.23 cm) (P < .001). Adjusted interval ΔWCs were 0.77 cm (95% CI = 0.29-1.23 cm) for nonusers, 1.76 cm (95% CI = 0.96-2.57 cm) for occasional users, and 3.04 cm (95% CI = 1.82-4.26 cm) for daily users (P = .002 for trend). This translates to ΔWCs of 0.80 inches for nonusers, 1.83 inches for occasional users, and 3.16 for daily users over the total SALSA follow-up. In subanalyses stratified for selected covariates, ΔWC point estimates were consistently higher in DS users.

Conclusion: In a striking dose-response relationship, increasing DSI was associated with escalating abdominal obesity, a potential pathway for cardiometabolic risk in this aging population.

Keywords: abdominal obesity; artificial sweeteners; diet soda; nonnutritive sweeteners; waist circumference.

Figure 1

Longitudinal change in waist circumference (black squares) and body mass index (BMI: grey diamonds), by sex, from the San Antonio Heart Study baseline exam through the third San Antonio Longitudinal Study of Aging (SALSA) follow-up, for SALSA participants who returned to this last exam. Dashed trend lines represent third-order polynomial fits to the data points.

Figure 2

Mean change in body mass index (kg/m² (95% confidence interval)) per follow-up interval, by diet soda consumption category at the beginning of the interval, adjusted for sex, age, ethnicity, education, neighborhood, beginning body mass index, leisure physical activity level, diabetes, smoking status, and length of interval.

Figure 3

Mean change in waist circumference (cm (95% confidence interval)) per follow-up interval, by diet soda consumption category at the beginning of the interval, adjusted for sex, age, ethnicity, education, neighborhood, beginning waist circumference, leisure physical activity level, diabetes, smoking status, and length of interval.