A high prevalence of vitamin D deficiency has been reported in non-Western immigrants in Norway. Our objective was to test whether written information about how to improve vitamin D status could improve the vitamin D status in immigrants mothers attending child health clinics. In this cluster randomized controlled trial in eight child health clinics in Oslo, mothers aged 18-43 years with Pakistani, Turkish, or Somali background were included when their infants were 6 weeks old. The public health nurses gave the intervention group a brochure with information on how to improve vitamin D status, written in their native language. They were compared with a control group receiving usual care, consisting of oral information only. The principal outcome measure was increase in serum 25-hydroxyvitamin D [s-25(OH) D] in mothers 7 weeks later. Forty-four mothers completed the study. Mean baseline s-25(OH) D was 29.1 (14.8) nmol l(-1) in the intervention and 19.4 (9.2) in the control group. There was no significant increase in s-25(OH) D from baseline to follow-up in the intervention [6.3 (95%CI: -1.9, 14.4) nmol l(-1) )] or in the control group [2.9 (95% CI [confidence interval]: -1.2, 7.0) nmol l(-1) ]. When adjusting for baseline s-25(OH) D concentration the mean difference in increase between the intervention and control group was 1.4 (95% CI: -18.7, 21.4) nmol l(-1) (P = 0.87). Adjustment for ethnicity, season and mother's educational background did not alter the results. In sum, providing immigrant mothers with written information about how to improve their vitamin D status did not have an effect on the mothers' vitamin D status.
© 2010 Blackwell Publishing Ltd.