Bone Abstracts

Background: Improving the general population’s vitamin D status through food fortification is part of an ongoing debate. Vitamin D status during pregnancy may influence the long-term bone health of offspring; yet conflicting results have been reported and none of the studies have examined paediatric fracture as outcome.

Method: The influence of extra vitamin D exposure during prenatal life and risk of fracture during adolescence was determined by comparing subjects born before and after the termination of a mandatory vitamin D fortification program, applied in Denmark from 1961 to 1985, the effect of which has never been evaluated. For subjects born in 1983–1988, civil registration numbers were linked to the National Patient Registry for incident and recurrent fractures at ages 12–18 years. Semi-parametric multiplicative models for mean functions were used to assess the association between vitamin D exposure and occurrence of fractures, accounting for season of birth.

Results: A total of 103.569 exposed and 114.210 unexposed subjects were identified. Among those 11.693 exposed and 11.427 unexposed subjects sustained fractures. Within each season of birth, the wrist/forearm and ankle fracture rates in the exposed individuals were significantly greater than the rate for the unexposed group, e.g. the estimated rate ratio for wrist/forearm fracture comparing exposed to unexposed individuals born November–January: RR=1.20; 95% CI: 1.12, 1.28. There was no significant association between exposure and the rate of clavicle fractures (Table 1).

Conclusion: Among adolescents exposure to extra vitamin D from food fortification during prenatal life, seems related to an increased risk of fractures, in particular wrist/forearm and ankle.