Chronic Intake of Energy Drinks and Their Sugar Free Substitution Similarly Promotes Metabolic Syndrome

Abstract

Energy drinks containing significant quantities of caffeine, taurine and sugar are increasingly consumed, particularly by adolescents and young adults. The putative effects of chronic ingestion of either standard energy drink, Mother^TM (ED), or its sugar-free formulation (sfED) on metabolic syndrome were determined in wild-type C57BL/6J mice, in comparison to a soft drink, Coca-Cola (SD), a Western-styled diet enriched in saturated fatty acids (SFA), and a combination of SFA + ED. Following 13 weeks of intervention, mice treated with ED were hyperglycaemic and hypertriglyceridaemic, indicating higher triglyceride glucose index, which was similar to the mice maintained on SD. Surprisingly, the mice maintained on sfED also showed signs of insulin resistance with hyperglycaemia, hypertriglyceridaemia, and greater triglyceride glucose index, comparable to the ED group mice. In addition, the ED mice had greater adiposity primarily due to the increase in white adipose tissue, although the body weight was comparable to the control mice receiving only water. The mice maintained on SFA diet exhibited significantly greater weight gain, body fat, cholesterol and insulin, whilst blood glucose and triglyceride concentrations remained comparable to the control mice. Collectively, these data suggest that the consumption of both standard and sugar-free forms of energy drinks induces metabolic syndrome, particularly insulin resistance.

Keywords: artificial sweetener; blood glucose; body fat; brown adipose tissue; cholesterol; energy drinks; insulin; metabolic syndrome; triglycerides.

Figure 1

Chow, drink and nutrients consumption. The mice received no liquid intervention (control), Mother (ED), sugar-free Mother (sfED), Coca-Cola (SD), saturated fat enriched diet (SFA) or SFA with ED (SFA + ED) for 13 weeks. The chow and drink consumption was recorded twice weekly, and the total consumption over the 13-week experimental period is presented as per mouse. Statistical analyses were unable to be run because the data does not give errors.

Figure 2

Weight gain and body fat. The mice received no liquid intervention (control), Mother (ED), sugar-free Mother (sfED), Coca-Cola (SD), saturated fat enriched diet (SFA) or SFA with ED (SFA + ED) for 13 weeks. The mice were weighed weekly. The body fat percentage, white adipose tissue (WAT) volume, brown adipose tissue (BAT) volume and WAT:BAT ratio were recorded from five randomly selected mice per group (except for SD group) by using Skyscan in vivo x-ray microtomography. Statistical significance was tested using a one-way ANOVA with Fisher’s LSD post hoc test (* p < 0.05, ** p < 0.005, *** p < 0.0005, **** p < 0.0001).

Figure 3

Representative Skyscan images of adipose tissue. Representative Skyscan x-ray microtomography images for the mice received no liquid intervention (control), saturated fat enriched diet (SFA) or SFA with ED (SFA + ED) for 13 weeks are presented. White adipose tissue (WAT) is shown in red while brown adipose tissue (BAT) is shown in blue.

Figure 4

Blood glucose, lipids and insulin measurements. The mice received no liquid intervention (Control), Mother (ED), sugar-free Mother (sfED), Coca-Cola (SD), saturated fat enriched diet (SFA) or SFA with ED (SFA + ED) for 13 weeks. Blood glucose and HbA1c were measured at sacrifice with point-of-care device. Serum cholesterol and triglycerides were measured with colorimetric assay. Insulin was measured with a commercial ELISA kit. Triglyceride glucose index was calculated based on previous studies. Statistical analysis was performed using a one-way ANOVA with Fisher’s LSD post hoc analysis (n = 10; * p < 0.05, ** p < 0.005, *** p < 0.0005, **** p < 0.0001).

Figure 5

Serum cytokine concentrations. The mice received no liquid intervention (control), Mother (ED), sugar-free Mother (sfED), Coca-Cola (SD), saturated fat enriched diet (SFA) or SFA with ED (SFA + ED) for 13 weeks. Serum concentrations of inflammatory cytokines TNF-α, IL-4, IL-6 and IL-10 were measured using a commercial cytokine beads array kit. Interpolated values are presented as mean ± SEM for each cytokine. Statistical analysis was performed using a one-way ANOVA with Fisher’s LSD post hoc analysis (n = 10; * p < 0.05, ** p < 0.005).