Intake of calcium/vitamin D supplement in Iranian postmenopausal women.

In Iran, the last National Nutrition and Dietary Survey [1] showed that about 80% of Iranians do not meet the estimated average requirement for calcium. While foods are not generally fortified in Iran, dietary supplement may be a convenient way to prevent nutritional deficiency in high-risk population groups including the elderly [2, 3]. There is however, no data on supplement usage by older adults in Iran. This study assessed calcium/vitamin D supplement use among postmenopausal women with undiagnosed osteoporosis and normal bone women living in urban and rural areas in Guilan, northern Iran.

This study is part of a survey conducted to examine prevalence of osteoporosis among elderly women in Guilan, northern Iran. A total of 504 women from urban areas and 291 women from rural areas were selected. Diagnosis of osteoporosis was carried out using quantitative ultrasound technique and positive cases were confirmed by dual X-ray absorptiometry [4]. Serum 25(OH) D3 was measured using a commercial kit (BioSource 25OH-Vit.D3-CT Kit).

Overall usage of calcium/vitamin D supplement was 18.8% in this population. While osteoporosis was more prevalent among rural women, they used calcium supplement less frequently than urban women did (Table 1). More educated women had more calcium/vitamin D use than less educated women (32.6% vs. 23.9% P < 0.01). These data showed that frequency of calcium/vitamin D usage was less among women with osteoporosis than women who had normal bone density (17.7% vs. 19.2 P < 0.05).

Table 1

Age, employment status, body mass index, educational levels, prevalence of osteoprosis, vitamin D insufficiency, and supplement use of the women by urban and rural residence in Guilan, Iran

	Urban (n = 504)	Rural (n = 291)
Age (mean ± SD)	64.1 ± 9.0	62 ± 8.1*
BMI (kg/m2)	29.7 ± 5.3	27.5 ± 5.5*
Employed (%)	18.5	0.9
Educational level (%)
>5-year schooling	73.8	1.0
<5-year schooling	26.2	99.0
Vitamin D insufficiencya
(>30 ng/ml)	84.7	79.5*
Osteoprosis (%)	16.6	22.1**
Calcium/vitamin D
Supplement (%)	26.2	6.2*

*P < 0.001; **P < 0.05

aSerum vitamin D level was measured in 427 and 219 women in urban and rural areas, respectively

While there is insufficient knowledge about the actual amount of total nutrient that Iranian consumes from diet, it is estimated that the highest inadequate dietary intake is for calcium (80%) [1] and vitamin D (70%) [5]. Despite widespread deficiency of calcium and vitamin D only 18% of this population used calcium supplement daily. Considering that the fortification of food is not practiced in Iran (except for Iodine) there is a national need to remediate of vitamin and mineral deficiencies.

Intake of calcium/vitamin D supplement was less among those women who had undiagnosed osteoporosis than women with normal density bone. Moreover, more educated women were more likely to use calcium supplement than less educated women in this population. It has been shown that multivitamin/mineral supplements are generally used by individual who practice healthier life style [6]. In this population of postmenopausal women, rural women were more likely to have decreased bone mass than urban women. However, intake of calcium/vitamin D supplement among rural women was less than urban women.