Metabolic syndrome and its association with diet and physical activity in US adolescents

Background Research on the metabolic syndrome and its association with lifestyle behaviors in adolescents is important for identifying subgroups of youth at whom interventions should be targeted. Objective To examine the relationship of metabolic syndrome with diet and physical activity in US adolescents. Design A sample of 4,450 12- to 19-year-olds was obtained from 4-year combined data of the National Health and Nutrition Examination Survey 1999-2002. Method The metabolic syndrome was defined as having three or more of the following conditions: waist circumference >= 90th percentile for age/sex, fasting blood glucose >= 100 mg/dL (5.6 mmoUL), blood triglycerides >= 110 mg/dL (>= 1.2 mmol/L), HDL cholesterol <= 35 mg/dL (0.9 mmol/L), and systolic/diastolic blood pressure >= 90th percentile for height or taking antihypertensive drugs. Diet quality was assessed using the Healthy Eating Index and its components, and nutrient intakes. The association between the metabolic syndrome and physical activity was presented as the prevalence of metabolic syndrome by different physical activity levels. Results Overall prevalence of metabolic syndrome among US adolescents was 3.5%. More males than females (5.1% vs 1.7%; P<0.0001) had metabolic syndrome. The metabolic syndrome was 16 times higher in overweight adolescents (body mass index >= 95th percentile) compared to those with body mass index <85th percentile (14.5% vs 0.9%; P<0.0001). Prevalence of metabolic syndrome decreased with increments of overall Healthy Eating Index and fruit score quartiles. Higher overall Healthy Eating Index and fruit scores were associated with lower metabolic syndrome (P<0.001). There was a trend toward lower prevalence of metabolic syndrome in adolescents with high physical activity levels (2.6%) compared to those who had low (4.3%) or moderate (3.1%) physical activity levels. Conclusion Results support the need to engage adolescents in regular physical activity and healthful dietary practices to prevent excessive weight gain. Weight control should be recommended as the first-line intervention to decrease metabolic syndrome in adolescents.