McGrath J, Saari K, Hakko H, Jokelainen J, Jones P, Jarvelin MR, Chant D, Isohanni M. (2004) Schizophr Res. 67(2-3) 237-45
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Based on clues from epidemiology and animal experiments, low vitamin D during early life has been proposed as a risk factor for schizophrenia. The aim of this study was to explore the association between the use of vitamin D supplements during the first year of life and risk of developing schizophrenia.
Subjects were drawn from the Northern Finland 1966 Birth Cohort (n=9,114). During the first year of life, data were collected about the frequency and dose of vitamin D supplementation. Our primary outcome measures were schizophrenia, psychotic disorders other than schizophrenia, and nonpsychotic disorders as diagnosed by age 31 years. Males and females were examined separately.
In males, the use of either irregular or regular vitamin D supplements was associated with a reduced risk of schizophrenia (Risk ratio (RR)=0.08, 95% CI 0.01-0.95; RR=0.12, 95% CI 0.02-0.90, respectively) compared with no supplementation. In males, the use of at least 2000 IU of vitamin D was associated with a reduced risk of schizophrenia (RR=0.23, 95% CI 0.06-0.95) compared to those on lower doses. There were no significant associations between either the frequency or dose of vitamin D supplements and (a) schizophrenia in females, nor with (b) nonpsychotic disorder or psychotic disorders other than schizophrenia in either males or females.
Vitamin D supplementation during the first year of life is associated with a reduced risk of schizophrenia in males. Preventing hypovitaminosis D during early life may reduce the incidence of schizophrenia.