A recent study published in the British Journal of Nutrition used Danish data from a prenatal vitamin D fortification programme in the 1980s to study the effects of the programme on the future risk of fractures among children during puberty.
Previously conducted studies involving the measurement of vitamin D levels have confirmed that seasonal fluctuations in vitamin D levels exist across numerous cooler countries such as Denmark; these seasonal variations can most likely be explained using to the lack of vitamin D synthesis occurring in the bodies of individuals living in countries where periods of darkness frequently occur. During the darker times of year in countries characterized by cooler climates, Vitamin D levels will rely more heavily on Vitamin D gained from fortified foods and supplementation (taking Vitamin-D rich vitamins or supplements).
Presently, Denmark is deciding whether the reintroduction of vitamin-D fortified foods should be implemented in order to improve vitamin D levels in the Danish population; an international debate regarding whether enough evidence exists to justify the reintroduction of vitamin D fortified foods is globally underway. The Vitamin D fortification of margarine was compulsory until 1987 in Denmark, when it was eventually ended due to the speculation that the amount of Vitamin D added to the margarine was inadequately powerful enough to influence the Danish population’s Vitamin D levels. The researchers hypothesized that children born within the last two years of the compulsory vitamin D margarine fortification would be at a decreased risk of fractures, mainly of the ankle, forearm, and collarbone. On a similar note, the second hypothesis was that vitamin D fortification during the darker months of pregnancies would translate into a more substantial decrease in fracture risk observed among children.
All individuals recruited to participate in the study, published in the British Journal of Nutrition, were born during the period of 1983-1988. The children were followed from age ten until death, emigration or 18 years of age (whichever event occurred first). Statistical analyses of the data yielded the following P values regarding the relationship between season and exposure to vitamin D fortification, and overall fracture risk: P 0 .44 for boys and P 0.23 for girls. A P value can be defined as a value between 0 and 1 that indicates the strength of an association between different variables; P values ≤ 0.05 are generally considered to be indicative of strong evidence in support of a hypothesis, while P values >0.05 usually demonstrate weak evidence in support of a hypothesis.
Results from the study do not support the notion that the amount of extra prenatal vitamin D present in the fortified margarine provided to individuals during the Danish programme was potent enough to meaningfully affect Vitamin D levels irrespective of any season. The authors declare that additional studies replicating this one are required; despite a decrease in fracture events among children over the study period, the researchers believe that this could have been attributed to bicycle accidents.
Written By: Melissa Booker