Consumption of added sugars and development of metabolic syndrome components among a sample of youth at risk of obesity.

Previous evidence showed controversial links between added sugar intake, diet quality, and increasing prevalence of metabolic syndrome (MetS) components (abdominal adiposity, dysglycemia, elevated blood pressure, reduced high-density lipoprotein cholesterol (HDL-C), and hypertriglyceridemia) in youth, and most studied only its liquid source of sugar-sweetened beverages (SSB). To better understand the extent of the detrimental effects of added sugars from both liquid and solid sources to diets in terms of nutrient and food intake and metabolic consequences in children, 3 studies were undertaken to (i) quantify the associations of added sugar intake with overall diet quality and adiposity indicators; (ii) assess whether excess weight and glucose tolerance status modifies the associations between consumption of added sugars and MetS components; and (iii) evaluate whether consumption of added sugars predicts the development of MetS components over time. Data for these studies were obtained from the Quebec Adiposity and Lifestyle Investigation in Youth cohort. Caucasian children (8 to 10 years at baseline, N = 630) with at least 1 obese biological parent were recruited from 1040 Quebec primary schools and followed-up 2 years later (N = 564). Dietary intake, including added sugars (liquid vs. solid) and Canadian Healthy Eating Index (HEI-C) was assessed in three 24-h recalls at baseline. Adiposity indicators included measured height and weight for body mass index (BMI), BMI z score, waist circumference (WC), and fat mass (by dual-energy X-ray absorptiometry). Plasma glucose and insulin were measured at fasting and by oral glucose tolerance tests to calculate the homeostasis model assessment of insulin resistance (HOMA-IR) and the Matsuda IS index (Matsuda-ISI). Systolic blood pressure (SBP), concentration of triglycerides and HDL-C were measured by standard instruments. Multivariate linear regression models were used, adjusting for age, sex, pubertal status (by Tanner stage), energy intake, fat mass, and physical activity (by 7-day accelerometer). The main findings include the following: (i) Higher consumption of added sugars from SSB or solid sources was associated with lower nutrient density and lower HEI-C. Positive associations with adiposity indicators were observed with consumption of added sugars from liquid sources only. (ii) Higher SSB consumption was associated with higher HOMA-IR and higher SBP among overweight children (≥85th BMI percentile), as well as higher SBP and higher WC among children with impaired glucose tolerance. These associations with metabolic indicators were not observed among children whose BMI was below 85th percentile. (iii) No association with added sugar intake was observed for 2-year changes in adiposity, but higher consumption of added sugars from liquid sources was associated with higher fasting glucose, higher fasting insulin, higher HOMA-IR, and lower Matsuda-ISI. In conclusion, this thesis suggested that consumption of added sugars from both solid and liquid sources was associated with a lower overall diet quality, but only added sugars from liquid sources was associated with adiposity indicators. Cross-sectional links with higher levels of SSB intake and MetS components were more evident among overweight/obese and glucose-intolerant children. Consumption of added sugars from liquid sources was not associated with changes in adiposity over 2 years, but was clearly associated with development of impaired glucose homeostasis and insulin resistance. This thesis presents further evidence on the nutritional and metabolic consequences of consuming added sugar from liquid and solid sources.