Prenatal exposure to vitamin D from fortified margarine and risk of fractures in late childhood: period and cohort results from 222 000 subjects in the D-tect observational study.

Mina Nicole Händel,Peder Frederiksen,Berit L Heitmann,Cyrus Cooper,Clive Osmond,Bo Abrahamsen

doi:10.1017/s000711451700071x

Abstract

Prenatal low vitamin D may have consequences for bone health. By means of a nationwide mandatory vitamin D fortification programme, we examined the risk of fractures among 10-18-year-old children from proximate birth cohorts born around the date of the termination of the programme. For all subjects born in Denmark during 1983-1988, civil registration numbers were linked to the Danish National Patient Registry for incident and recurrent fractures occurring at ages 10-18 years. Multiplicative Poisson models were used to examine the association between birth cohort and fracture rates. The variation in fracture rates across birth cohorts was analysed by fitting an age-cohort model to the data. We addressed the potential modification of the effect of vitamin D availability by season of birth. The risk of fractures was increased among both girls and boys who were born before the vitamin D fortification terminated in 1985 (rate ratio (RR) exposed v. non-exposed girls: 1·15 (95 % CI 1·11, 1·20); RR exposed v. non-exposed boys: 1·11 (95 % CI 1·07, 1·14). However, these associations no longer persisted after including the period effects. There was no interaction between season of birth and vitamin D availability in relation to fracture risk. The study did not provide evidence that prenatal exposure to extra vitamin D from a mandatory fortification programme of 1·25 µg vitamin D/100 g margarine was sufficient to influence the risk of fractures in late childhood, regardless of season of birth. Replication studies are needed.

Highlights

Based on serum 25-hydroxy vitamin D3 (25(OH)D3) measurements, studies have shown a pronounced seasonal variation in vitamin D status in Denmark and other countries with latitudes above 35° North and South[1,2], most likely related to insufficient actinic vitamin D synthesis during the darker part of the year in such countries
Until 1 June 1985, vitamin D fortification of margarine was mandatory in Denmark, but fortification was abolished, related to an unsupported assumption that the amounts added to margarine were too small to impact the dietary needs of vitamin D in the Danish population[3]
It was hypothesised that the vitamin D fortification during sundeprived months of gestation would be associated with the greatest risk reduction of offspring childhood fractures

Summary

Introduction

Based on serum 25-hydroxy vitamin D3 (25(OH)D3) measurements, studies have shown a pronounced seasonal variation in vitamin D status in Denmark and other countries with latitudes above 35° North and South[1,2], most likely related to insufficient actinic vitamin D synthesis during the darker part of the year in such countries. Until 1 June 1985, vitamin D fortification of margarine was mandatory in Denmark, but fortification was abolished, related to an unsupported assumption that the amounts added to margarine were too small to impact the dietary needs of vitamin D in the Danish population[3]. We used this historical change in fortification legislation to examine the influence of extra prenatal vitamin D exposure from fortified margarine on Prenatal vitamin D and fractures in youth the risk of fractures during pubertal-related growth spurts, which has the highest fracture incidence[4]. It was hypothesised that the vitamin D fortification during sundeprived months of gestation would be associated with the greatest risk reduction of offspring childhood fractures

Methods

Results

Conclusion