Vitamin D insufficiency among postmenopausal women in urban and rural areas in Guilan, Northern Iran.

This study aimed to describe vitamin D status in postmenopausal women in urban and rural areas in Guilan, northern Iran. Between October 2004 and February 2005 a group of 750 women older than 50 years was randomly selected from urban and rural areas in Guilan. The participants were interviewed to collect data on age, educational level, body weight, height, employment status, reproductive history, medications, history of illness, and supplement use. Serum 25(OH) D was measured in 646 women (427 in urban areas and 219 women in rural areas). Serum 25(OH) D levels in urban and rural postmenopausal women were 18.5 ± 13.5 ng/ml and 22.9 ± 13.8 ng/ml (P < 0.0001), respectively. In urban and rural areas, 84.7% and 79.5% of the women had serum 25(OH) D levels less than 30 ng/ml, respectively. In this study, serum vitamin D levels and prevalence of vitamin D insufficiency was related to educational level in urban women. The urban women in the lowest educational level (<5 years schooling) had a better vitamin D status than other educational groups. This study showed that a high proportion of postmenopausal women living in Guilan province had vitamin D insufficiency. Vitamin D inadequacy was more common in urban areas and especially in the upper social class. Supplement use and national strategies to prevent vitamin D insufficiency are strongly needed in this community.