[Analysis for the blood mineral content of children aged 3 to 12 years in 7 cities and 2 towns in China].

Objective: To investigate the status of blood mineral content of children aged 3 to 12 years in Chinese cities and countryside and explore the possible related influencing factors.

Methods: The multistage stratified cluster random sampling was used to select one kindergarten and one primary school in seven cities (Beijing and Guangzhou and so on) and two towns randomly. Firstly, we selected one bottom class, middle class, top class in one kindergarten and one second grade and fifth grade in one primary school randomly. Then all of the healthful students of these classes were investigated and the blood mineral content of calcium, magnesium, lead, iron, copper, and zinc were detected.

Results: In the research, 1 842 students were investigated. The means of calcium, magnesium, lead, iron, copper, and zinc were in the standard range. The blood lead content of the boys was higher than that of the girls. The blood mineral content of different ages had statistical significance. The blood calcium and blood copper contents of the preschool children were higher than those of the school children. However, the school children had significantly higher blood lead, iron, and zinc contents in comparison with those of the preschool children. The incidences of iron deficiency and zinc deficiency were 35.5% and 39.6%, respectively. The incidence of iron deficiency and zinc deficiency of different ages had statistical significance, and with the age increasing, the incidence showed a decreasing trend. The incidences of iron deficiency and zinc deficiency of children whose age was more than or equal to 3 years and less than 4 years were up to 47.1% and 64.6%, respectively. The incidence of iron deficiency of the children in the countryside area was significantly higher than those in the first-tier cities. However, the incidence of zinc deficiency of the children in the countryside area was significantly lower than those in the first-tier cities and second-tier cities.

Conclusion: The status of iron deficiency and zinc deficiency of children aged 3 to 12 years in Chinese cities and countryside were still serious. We should pay more attention to the nutrition interventional research on iron and zinc.