AB1389 Associations between a priori defined dietary patterns and longitudinal changes in bone mineral density in adolescents
Authors: T. Monjardino, R. Lucas, E. Ramos, H. Barros
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Maximizing the skeletal peak bone mass in early life is thought to predict a relatively higher bone mass and hence greater fracture risk reduction later in life. Accordingly, there has been considerable research aiming to understand in which extent modifiable environmental factors, such as nutrition, act on bone accrual during adolescence. Even though some isolated nutrients have been identified as determinants of bone accrual, it seems more interesting to assess the impact of overall diet in bone quality, in order to design realistic public health interventions. Assessing the compliance of an individual's diet with <i>a priori</i>-defined dietary patterns, i.e. patterns defined based on presumed health effects, allows to uncover potential associations between diet in its entirety and bone quality indices. <h3>Objectives</h3> To quantify the association between forearm bone mineral density in early and late adolescence and adherence to <i>a priori</i> defined dietary patterns. <h3>Methods</h3> We analysed prospective data from 1180 adolescents (50.7% males) from the EPITeen cohort (adolescents born in 1990 and present at schools in Porto during the 2003/2004 school year) assessed at 13 and at 17 years old. In both evaluations, a physical examination including height, weight and forearm bone mineral density (BMD) using dual-energy X-ray absorptiometry was carried out. Dietary intake was assessed at 13 using a validated food frequency questionnaire and adherence to <i>a priori</i> defined dietary patterns was measured using a Mediterranean Diet Quality Index, a Dietary Approaches to Stop Hypertension Index and the Oslo Health Study (OHS) Dietary Index. Using tertiles of adherence to <i>a priori</i> patterns as the main exposure, associations were estimated cross-sectionally (with BMD at the age of 13) and prospectively (with BMD at 17 and bone gain between 13 and 17 years) using linear regression coefficients. All analyses were adjusted for BMI, total energy intake and, in girls, for menarche age. <h3>Results</h3> Mean (SD) forearm BMD increased from 0.368 (0.055) at 13 years-old to 0.440 (0.051) g/cm<sup>2</sup> at 17 years-old in girls and from 0.342 (0.050) to 0.452 (0.075) g/cm<sup>2</sup> in boys. We observed no significant differences in mean BMD at 13 and 17 years of age by tertiles of adherence to the different<i>a priori</i> dietary patterns. No associations were identified with adherence to any of the <i>a priori</i> dietary patterns and BMD at 13 or 17 or BMD gain in girls. However, among boys, a significant linear trend towards increased BMD at 17 with increasing adherence to the Mediterranean Diet pattern was observed, being the average BMD (mg/cm<sup>2</sup>) significantly higher in boys in the highest tertile of adherence (1.08, 95%CI: 0.53; 2.68) when compared to those in the lowest tertile. <h3>Conclusions</h3> Significant relationships were not apparent between the <i>a priori</i> dietary patterns used and forearm BMD in early or late adolescence. The selected dietary patterns may not capture the elements of diet that are truly important in determining adolescent bone quality or, given the relative adequacy of nutrient intake in high-income populations, dietary patterns may not add substantially to other determinants of BMD at this age. <h3>Disclosure of Interest</h3> None Declared