Sugar-Sweetened Beverage Consumption and Cardiometabolic Risk Factors.
Background: Currently, sugar-sweetened beverages (SSB) account for 6% and 9% of energy
intake in American adults and children, respectively. Recently, much attention has
focused on the potential, detrimental public health impact of SSB consumption on
cardiometabolic diseases. Many observational studies have examined the associations
between habitual SSB intake and cardiometabolic ri... read moresk factors; however, little evidence
exists examining the role of habitual SSB intake on ectopic fat accumulation and insulin
resistance. Aims: The objective of this dissertation is to examine the associations
between habitual SSB intake and 1) fat accumulation in abdominal visceral adipose and
subcutaneous depots, 2) risk of fatty liver disease, and 3) progression of insulin
resistance and risk of pre-diabetes. Methods: Data from the Framingham Offspring cohort
and Third Generation cohorts were examined. Habitual intake of SSB and diet soda was
assessed by a validated food frequency questionnaire. Ectopic fat accumulation in
visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and liver were measured
using computed tomography. Fatty liver disease was defined using measures of liver fat
content. Insulin resistance was assessed using homeostatic model assessment insulin
resistance (HOMA-IR). Aim 1: Least-squares means of VAT, SAT, and VAT:SAT ratio across
SSB and diet soda categories were calculated in a cross-sectional analysis of 2,596
middle-aged participants. Aim 2: Odds ratios of fatty liver disease in SSB and diet soda
consumers relative to non-consumers were estimated in a separate cross-sectional
analysis of 2,634 participants. Aim 3: Least-squares means of progression of HOMA-IR
(n=2,092 participants) and relative risk of incident pre-diabetes and diabetes (n=1,981
participants) were calculated in a prospective analysis utilizing over 7 years of data.
Results: Aim 1: SSB consumption was significantly associated with a greater VAT
(P-trend<0.001) and a reduced SAT (P-trend<0.001). SSB intake was also positively
associated with an increased VAT:SAT ratio (P-trend<0.001). Daily SSB consumers had a
10% higher absolute VAT volume, 12% lower absolute SAT volume, and a 15% greater VAT:SAT
ratio compared to SSB non-consumers. Aim 2: After adjustment for multiple confounders
including BMI, SSB consumption was associated with increased risk of fatty liver disease
(P-trend=0.02), with a 55% increased risk of fatty liver disease in daily consumers of
SSB compared to non-consumers. SSB consumers tended to have a greater liver fat content,
however, this association was only significant in overweight and obese participants
(P-trend=0.03). SSB intake was also positively associated with ALT levels
(P-trend=0.007), a surrogate marker of fatty liver disease. Aim 3: SSB intake was
positively associated with change in HOMA-IR (P-trend=0.04). SSB intake was associated
with a higher incident risk of pre-diabetes (P-trend=0.03), with those in the highest
category of consumption (>3 servings/week, median 6 servings/week) having a 39%
increased incidence of pre-diabetes compared with non-consumers. Diet soda intake was
not associated with abdominal ectopic fat accumulation (VAT or VAT:SAT ratio), risk of
fatty liver disease, or progression of insulin resistance. Summary and Conclusion:
Collectively, our observations contribute to the existing literature showing that,
independent of body weight, habitual SSB intake is associated with an increased fat
partitioning to VAT, greater prevalence of fatty liver disease, and elevated insulin
resistance. Given that SSB are a major source of added sugars in the American diet,
these results support the hypothesis that excessive habitual intake of SSB is associated
with greater cardiometabolic risk.
Thesis (Ph.D.)--Tufts University, 2014.
Submitted to the Dept. of Nutritional Epidemiology.
Advisor: Nicola McKeown.
Committee: Caren Smith, Caroline Fox, Edward Saltzman, and Paul Jacques.
Keywords: Nutrition, and Epidemiology.read less