The impact of diet, body composition, and physical activity on child bone mineral density at five years of age-findings from the ROLO Kids Study.

Bone health is extremely important in early childhood because children with low bone mineral density (BMD) are at a greater risk of bone fractures. While physical activity and intake of both calcium and vitamin D benefit BMD in older children, there is limited research on the determinants of good bone health in early childhood. The aim of this cross-sectional study was to investigate the impact of diet, physical activity, and body composition on BMD at five years of age. Dietary intakes and physical activity levels were measured through questionnaires. Whole body BMD was measured by dual-energy X-ray absorptiometry in 102 children. Child weight, height, circumferences, skinfolds and serum 25-hydroxyvitamin D (25OHD) concentrations were assessed. There was no association between BMD and dietary calcium, dietary vitamin D, 25OHD, physical activity, or sedentary behaviour. Several measures of body composition were significantly positively associated with BMD; however, neither fat mass nor lean body mass was associated with BMD.Conclusion: Although we found no association between self-reported dietary and lifestyle factors and bone health in early years, increased body size was linked with higher BMD. These findings are important as identifying modifiable factors that can improve bone health at a young age is of utmost importance.What is Known:• Bone health is extremely important in early childhood, as children with low bone mineral density (BMD) are at greater risk of bone fractures.• Physical activity has been found to be beneficial for bone health in adolescents, and body composition has also been associated with BMD in teenage years.• Limited research on the determinants of good bone health in early childhood.What is New:• No association between self-reported lifestyle and dietary factors with bone health in early childhood.• Increased body size was associated with higher BMD at five years of age.

An exploratory analysis of associations of diet, sun exposure, and body composition with 25OHD at five years of age: Findings from the ROLO Kids Study.

Serum 25-hydroxyvitamin D (25OHD) is the main circulating form of vitamin D in the blood. Vitamin D status in adults is determined by numerous factors such as oral intake, skin generation, and body composition. However, there is limited understanding regarding determinants of 25OHD in young children. The aim of this study was to identify modifiable factors that may act as determinants of 25OHD at five years of age. Analysis conducted on 79 children from the ROLO Kids study. Dietary intakes and dietary habits were measured using a food frequency questionnaire and levels of sun exposure were assessed using a lifestyle questionnaire, both completed by the mother. Child weight, height, and skinfolds were measured. Vitamin D status was sufficient (25OHD > 50 nmol/L) in 61% of the participants. Neither reported dietary vitamin D nor calcium intake was significantly associated with 25OHD. Intakes of standard milk, eggs, and oily fish were not associated with 25OHD. However, reported consumption of fortified milk, and more than 7 bowls of cereal a week were independently associated with higher 25OHD (p < 0.001 and p = 0.049, respectively). Sun exposure (measured as obtaining at least half an hour of sun per day) was not significantly associated with 25OHD, but reported use of sunscreen was associated with higher 25OHD (p = 0.016). There was no association of body composition with 25OHD. These findings suggest the primacy of dietary and lifestyle habits as indicators of 25OHD in early childhood. This may have utility in identifying at-risk individuals for public health campaigns about education surrounding dietary habits, which may be useful to ensure sufficient vitamin D status within this age group.