Association Between Screen Time and Physical Activity with Sufficient Vitamin D Status in Brazilian Adolescents: The Study of Cardiovascular Risks in Adolescents (ERICA)

Presentation Number: SUN 343
Date of Presentation: April 2nd, 2017

Beatriz D'Agord Schaan*1, Ana Carla Moreira da Silva2, Felipe Vogt Cureau3 and Kenia Baiocchi de Carvalho2
1Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, 2Universidade de Brasilia, 3Universidade Federal do Rio Grande do Sul

Abstract

Vitamin D deficiency is common worldwide, in all age groups and countries, causing nutricional rickets, osteomalacia and possibly other health problems. Particularly, adolescents are a high risk population for vitamin D deficiency, as they have increased demand of nutrients, and may have an inactive lifestyle, which contributes to less sun exposure. There is still under-reporting of this data in countries like Brazil, which has a continental size, a diversity of cultures and regional climate conditions that may interfere with vitamin D status. Aims: The aim of this study was to investigate the association between physical activity and screen time with vitamin D status among Brazilian adolescents. Methods: This is a cross-sectional analysis of a subsample of the Study of Cardiovascular Risk in Adolescents (ERICA), composed of 1,155 students aged between 12 and 17 years living in four State capitals (Rio de Janeiro, Porto Alegre, Brasília and Fortaleza). Sociodemographic features and clinical data were obtained through self-administered questionnaires and standardized anthropometric and blood pressure measurements. Fasting blood samples for serum vitamin D (chemiluminescence of microparticles by immunoassay technique - CMIA) were succeed. The sufficient vitamin D status was defined by a serum level ≥ 30 ng/ml. The prevalence rates were estimated for the total sample and analyzed by sex. Weighted Poisson regression models were applied separately to investigate association between sufficient vitamin D status (outcome variable) and being active (≥ 300 minutes per week) or presenting high screen time (> 2 hours per day), both exposure variables. Analyses were adjusted for center, sample collection period, type of school, age, skin color, economic status, sexual maturation and nutritional status. Results: Prevalence of sufficient vitamin D status was 36.4% (95% CI 32.7- 40.4), lower in girls (28.6%, 95% CI 23.4 - 34.4), as compared to boys (44.3%, 95% CI 39.4- 49.3). Prevalence of sufficiently active adolescents was about twice as high among boys (65.9%, 95% CI 61.6-70.0), as compared to girls (33.3%, 95% CI 29.4-37.4). There was no difference in the prevalence of high screen-time between genders (overall sample: 62.6%, 95% CI 52.2-65.9). After model adjustments, for boys, being active was associated with sufficient vitamin D status (PR = 1.53, 95% CI 1.15 -2.05), not observed in girls. There was no association between screen time and vitamin D status in both sexes. Conclusions: In conclusion, only one third of Brazilian adolescents have adequate vitamin D levels (cutoff point of 30 ng/ml). The association between vitamin D sufficient status and physical activity in boys reinforce the importance of stimulating behavioral changes to promote adolescent health. The low number of adolescents with vitamin sufficiency leads questioning on the adequacy of the cutoff points proposed by guidelines.

 

Nothing to Disclose: BDS, ACMD, FVC, KBD