D-tecting Disease - From Exposure to Vitamin D During Critical Periods of Life

Study Overview
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Brief Summary
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Vitamin D deficiency is common among otherwise healthy pregnant women and may have consequences for them as well as the early development and long-term health of their children. However, the importance of maternal vitamin D status has not been widely studied. The present study is divided into a societal experiment (1) and a case-cohort study (2): The present study includes an in-depth examination of the influence of exposure to vitamin D early in life and during critical periods of growth for development of type 1 diabetes (T1D), type 2 diabetes, gestational diabetes, pre-eclampsia, obesity, asthma, arthritis, cancer, mental and cognitive disorders, congenital disorders, dental caries and bone fractures during child- and adulthood. The study is based on the fact that mandatory fortification of margarine with vitamin D, which initiated in 1937, was terminated in 1985. Apart from determining the influences of exposure prior to conception and during pre- and postnatal life, the investigators examined the importance of vitamin D exposure during specific seasons and trimesters, by comparing disease incidence among individuals born before and after the fortification. Additionally, a validated method was used to determine neonatal vitamin D status using stored dried blood spots (DBS) from individuals who develop the aforementioned disease entities as adults and their time and gender-matched controls. Unparalleled, the study will help determine the effects of vitamin D exposure during critical periods in life. There are a sufficient number of individuals to verify any effects during different gestation phases and seasons of the year. The results, which will change our current understanding of the significance of vitamin D, will enable new research in related fields, including interventional research designed to assess supplementation needs for different subgroups of pregnant women. Also, other health outcomes can subsequently be studied to generate multiple new interdisciplinary health research opportunities involving vitamin D.

Official Title
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D-tecting Disease - From Exposure to Vitamin D During Critical Periods of Life

Conditions
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Obesity, Tooth Diseases, Vitamin D Deficiency, Diabetes Mellitus, Pre-Eclampsia, Arthritis, Asthma, Bone Fracture, Birth Weight, Birth Disorder, Pregnancy Complications, Mental Disorder, Cancer, Congenital Disorders

Intervention / Treatment
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* Other: D-tect


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Born in Denmark around the fortification period Sufficient amount of blood from the DBS Exclusion Criteria: 1.Born outside Denmark Born outside the fortification period Insufficient amount of blood from the DBS or DBS not found
Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Exposed<br>Individuals born between June1983 and May1985 were exposed to the mandatory vitamin D margarine fortification during fetal life. Cases: individuals defined as having one of the aforementioned diseases of interest from the registers | Other: D-tect<br>* This study is based on a unique Danish social experiment that took place during a well-defined period between 1937 and December 1985, when it was mandatory to fortify all margarine with vitamin D (1.25 μg/100 g). This well-defined vitamin D fortification period makes it possible to investigate the impact of fetal exposure to extra vitamin D from food fortification on the risk of developing diseases later on. This study is possible due not only to the well-defined adjacent time window but also to the complete registration of every citizen via a civil registration number. This number can be linked, on an individual level, to Danish birth, patient and medical registries; social and ethnic registries; and clinical and other large databases Case-cohort study: vitamin D measurements from dried blood spots and the risk of diseases later on<br>|
| Non-exposed<br>Individuals born between September1986 and August 1988 were not exposed to the mandatory vitamin D margarine fortification during fetal life. Controls: cohort of matched disease-free individuals | Other: D-tect<br>* This study is based on a unique Danish social experiment that took place during a well-defined period between 1937 and December 1985, when it was mandatory to fortify all margarine with vitamin D (1.25 μg/100 g). This well-defined vitamin D fortification period makes it possible to investigate the impact of fetal exposure to extra vitamin D from food fortification on the risk of developing diseases later on. This study is possible due not only to the well-defined adjacent time window but also to the complete registration of every citizen via a civil registration number. This number can be linked, on an individual level, to Danish birth, patient and medical registries; social and ethnic registries; and clinical and other large databases Case-cohort study: vitamin D measurements from dried blood spots and the risk of diseases later on<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Obesity | Register based | 2012-2025 | 
| Type 1 diabetes | Register based | 2012-2016 | 
| Pre-eclampsia | Register based | 2012-2025 | 
| Bone facture | Register based | 2012-2025 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Type 2 diabetes | Register based | 2014-2025 | 
| Gestational diabetes | Register based | 2014-2025 | 
| Asthma | Register based | 2015-2025 | 
| Arthritis | Register based | 2018-2025 | 
| Birth weight | Register based | 2014-2019 | 
| Mental diseases | Register based | 2012-2025 |