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Schizophrenia increased 40 percent for Spring births after Danes stopped vitamin D fortification – April 2014

Prenatal Vitamin-D levels and Adult Schizophrenia: Evidence from A Danish Societal Experiment

Raymond K (1). Knop J (1), Heitmann BL (1-3).
1. Institute of Preventive Medicine, Bispebjerg and Frederiks-berg Hospital, The Capital Region, Copenhagen, Denmark.
2. The Boden Institute of Obesity, Nutrition, Exercise 8 Eating Disorders, University of Sydney, Australia.
3. National Institute of Public Health, University of Southern Denmark, Denmark.
Background: Of late, the influence of prenatal nutrition on the long term health of progeny has received increased scrutiny. The Dtect project, aims to elicit the role of prenatal vitamin-D levels on future health outcomes such as the development of schizophrenia amongst progeny later in life. The first step in the Dtect protocol is to study the potential association between prenatal vitamin-D levels and the development of adult schizophrenia by examining a societal experiment undertaken by the Danish government from 1961 to 1985. During this period, the Danish government mandated the fortification of margarine with vitamin-D, 1.25mg/100g. In this talk we will analyze and discuss the benefits associated with prenatal consumption of vitamin-D fortified foods in terms of the development of schizophrenia amongst the progeny later in life.
Methods: In order to assess the potential health effects of consuming vitamin-D fortified foods, we performed a registry based study, taking advantage of the extensive Danish public health registries. At birth, every Dane is assigned a CPR number and information pertaining to date of birth, current living status and gender is stored in the CPR registry. By linking the CPR registry with the National Psychiatric Research Register, we were able to collect information pertaining to every Dane born 2 years prior to and after each change in the Danish fortification policy between 1961 and 1985. Using Age-Period-Cohort models we examined the incidence rate of schizophrenia amongst the birth cohorts prior to and after termination of the fortification policy in 1985. Further subdividing the birth cohorts by month, we were able to examine differences in the incidence rates of schizophrenia by season of birth. This is of particular importance due to the seasonal dependence on dietary sources of vitamin-D in Denmark. To test the hypothesis of an association between the prenatal exposure to vitamin-D fortified foods and the risk of the progeny developing schizophrenia later in life. Cox regression models were fit. Cox regression models were also used to test the hypothesis of interactions between season of birth and exposure to vitamin-D fortified foods.
Results: The results of the Cox regression analysis indicated that there was a significant interaction between the season of birth and exposure to vitamin-D fortified margarine amongst children born between 1983 and 1987. Specifically, in regards to children born after the cessation of vitamin-D fortification, children born from May-July have an increased risk, (hazard ratio 1.40 (1.05,1.85)), of developing schizophrenia compared to children born between November and January. In contrast, there was no evidence to suggest a similar association amongst the children born while the vitamin-D fortification policy was in place.
Conclusion: The results of our study suggest that the vitamin-D fortification policy enacted in Denmark until June 1st, 1985 had a protective effect amongst children born during the spring in regards to later development of schizophrenia.

Comment by VitaminDWiki

This was presented at Vitamin D conference in England - April 23-25 2014
Spring is typically the season with the lowest vitamin D levels, that is, the time that fortification would help the most
Margarine fortification was only 50 IU of vitamin D/100 gram, but every bit helps

See also VitaminDWiki

14 reasons to think that schizophrenia is associated with low vitamin D
1) 97% of patients with schizophrenia are vitamin D deficient
2) Schizophrenia varies with latitude (UVB) by 10X (controversy)
3) Schizophrenia is more common in those with dark skin (when away from the equator)
4) Schizophrenia is associated with low natal vitamin D
5) Schizophrenia has been increasing around the world when vitamin D has been decreasing (controversy)
6) Schizophrenia is associated with low birth rate, which is associated with low vitamin D
7) Schizophrenia is associated with Autism which is associated with low vitamin D
8) Schizophrenia Bulletin Editorial (Jan 2014) speculated that Vitamin D could be a major player
9) Schizophrenia 2X more likely if low vitamin D - meta-analysis
10) Schizophrenia increased 40 % for Spring births after Danes stopped vitamin D fortification
11) Schizophrenia is associated with season of birth
12) Schizophrenia is associated with poor Vitamin D Receptor genes
13) Schizophrenia risk is decreased if give Vitamin D after birth
14) Schizophrenia symptoms reduced when Vitamin D levels are restored