The Relationship Between Serum 25-Hydroxyvitamin D, Vitamin D and Calcium Intake, and Adiposity in Infants

Purpose: National prevalence of childhood overweight and obesity has plateaued in recent years, but rates remain high, with approximately 10% among children“high weight.” The relationship between adiposity and serum 25-hydroxyvitamin D [25(OH)D] status has been well-explored in older individuals, with inconsistent results. Furthermore, previous studies have suggested a relationship between adequate consumption of calcium and vitamin D and healthy weight status in older children and adults. However, in the infant population, there are few studies detailing the interaction between body composition and serum 25(OH)D or intake of calcium and vitamin D. Our study aims were to assess the association between serum 25(OH)D and body composition and to examine the association between adiposity and dietary intake of calcium and vitamin D in a sample of infants and toddlers. Methods: Our population included healthy male and female infants and toddlers from Pittsburgh, PA who participated in the “Practices Affecting Vitamin D Status in Pittsburgh Infants and Toddlers” study. Parents completed a Vitamin D and Sunlight Exposure Questionnaire, which assessed dietary intake of foods high in calcium and vitamin D as well as daily sunlight exposure (≥2 hours vs. \u3e2 hours). Anthropometric measures and bloodwork for serum 25(OH)D were obtained during at the time of the study visit. Weight-for-length (WFL) percentile status was determined using WHO growth standards (low weight97.7 %ile) and WFL z-scores were calculated. ANOVA was used to compare mean serum 25(OH)D and calcium and vitamin D intake by WFL status. Chi square analysis was used to evaluate the relationship between serum 25(OH) D status (deficient =/mL, insufficient = 12-20 ng/mL, sufficient \u3e20 ng/mL), calcium intake status (sufficient = \u3e700 mg), vitamin D intake status (sufficient = \u3e400 IU) and WFL percentile status. Pearson’s correlation coefficient was used to assess the strength and significance of associations between serum 25(OH)D, calcium and vitamin D intake and WFL z-score. The analysis was repeated after subdivision by race and sun exposure. Results: 125 infants and toddlers (9 to 24 months of age, 68% African American) participated in the study. Approximately 11% of the population had a high weight. Mean vitamin D intake (~600 IU/d) and median calcium intake (~1550 mg/d) exceeded recommendations. Prevalence of high weight was higher among children with adequate intake compared to those who consumed less than the recommendations (calcium: 41% vs. 36%, respectively; vitamin D: 45% vs. 29%, respectively). However, this difference was not statistically significant. Mean serum 25(OH)D level (37 ng/mL) was sufficient. When compared across WFL status, neither mean serum 25(OH)D nor mean intake of calcium and vitamin D varied significantly. No significant correlation was found between WFL and serum 25(OH)D for the cohort or any of the subgroups examined. Conclusions: Rates of infant overweight and obesity in our sample are similar in comparison with the national average. Our results do not support a relationship between calcium and vitamin D intake on weight status or an association between serum vitamin D and body composition in children of this age. Future studies are needed to re-examine these relationships in a larger group of children of more evenly distributed weight status