Characteristics of included studies.

*“young Finnish men”, “homogenous with regards to age”; †Norway, Denmark, Belgium, US, Austria, Scotland; #various latitudes; ‡significantly higher than placebo; §significantly lower than vitamin D group, ¤800 IU/year for 2 years and 2000 IU/year during the 3rd year. Administration interval: A, 100,000 IU/4 weeks; B, 100,000 once; C, 100,000 IU/3 months; D, 200,000 IU initially, 200,000 after 1 month and thereafter 100,000/month. The study by Lehouck et al (24) was not included in the meta-analysis, see Materials and Methods for details.