Efecto de un programa escolar de intervención nutricional y conductual sobre los niveles de vitamina D y síndrome metabólico del adolescente

Abstract

ABSTRACT Introduction: Child and adolescent obesity is a serious public health concern, involving severe comorbidities if the obesity endures into adulthood. The increase in child and adolescent obesity responds, among other factors, to environmental factors that emphasize poor dietary habits and an increasingly sedentary lifestyle. Moreover, obesity is considered a risk factor for developing vitamin D deficiency, interacting with insulin resistance and inflammation. Our working hypothesis draws from the increase in the prevalence of excess weight and obesity in children and adolescents and the high prevalence of vitamin D deficiency in this population and the need for intervention measures. We will assess the effect of an educational program for nutritional and behavioural intervention (PNBI) on weight and levels of vitamin D in adolescents from Granada. Objectives: To study the prevalence of overweight and obesity, dietary habits, vitamin D levels and parameters of the metabolic syndrome (MS) in a representative sample of adolescents from Granada. To develop an Educational Program for Nutritional and Behavioural Intervention (PNBI) and study the above parameters before and after developing the PNBI. Subjects and Methods: We selected a total of 2246 students from E.S.O. (Compulsory Secondary Education) (1102 males), aged between 12 and 16 years, belonging to schools in the city of Granada and nearby towns. A total of 263 students were randomly selected to participate in the PNBI during the school year. The PNBI was based on the teaching of nutritional recommendations for age and dietary changes as well as lifestyle adjustments by fortnightly lessons of 45 minutes. In addition, each day, they received a Mediterranean breakfast at school that assured they receive 200 IU of vitamin D. At the beginning and end of the school year (May and September respectively), the body mass index (BMI) and the waistline perimeter was determined. They were also surveyed about their dietary habits by using a frequency test about the consumption of valid foods and about exercise habits. In addition, body composition was studied by impedance measures, by measuring blood pressure, and serum determinations of glucose, vitamin D, cholesterol (LDL and HDL), and triglycerides. Results: We found a prevalence of overweight of 22.8% in men and 15.8% in women and 6.7% of obesity in men and 3.1% for women. After the intervention, the prevalence of overweight decreased among both male and female students (21.3% vs. 31.5%, p <0.001 in males; 14.0% vs. 21.7%, p <0.001 for women). The prevalence of obesity decreased in both male (5.5% vs. 7.9%, p <0.001) and females (3.9% vs. 4.7%, p <0.001). After the intervention, both sexes significantly decreased total energy volume and total fat intake (p <0.001). A significant increase in lean mass was observed in males and females and the percentage of students with MS criteria was significantly lower after the PNBI (32% vs. 19.7%, p <0.001). Prior to the intervention, 18.7% of adolescents had vitamin D deficiency, and 38.3% had insufficiency. After the intervention, the prevalence of vitamin D deficiency is reduced to 0.46% (p <0.0001) and vitamin D insufficiency to 19.1% (p <0.0001). The effect of the intervention program on the values of vitamin D depends on the BMI (p <0.006), fat mass (p <0.05), linoleic acid consumption (p <0.03) and plasma cholesterol. Conclusions: Spain currently has a high prevalence of excess weight and obesity that places it as one the top countries in the European Union with this problem. The Educational Program for Nutritional and Behavioural Intervention significantly decreases the prevalence of overweight and obesity in adolescents of both sexes, changing dietary habits and lifestyle, changing body composition and decreasing the prevalence of MS. The prevalence of insufficiency and vitamin D deficiency found in healthy adolescents is high. After the PNBI, vitamin D deficiency is corrected and insufficient vitamin D is significantly reduced. The effect of PNBI on serum levels of 25 (OH) D is related to weight and body fat. Increased waist circumference is a risk factor for developing the adolescent insufficiency or deficiency of vitamin D.