Prevalence of zinc deficiency in junior high school students of Tehran City

Zinc deficiency is a health problem in many communities especially among adolescents because of pubertal growth sprout. This investigation was carried out to determine the epidemiology of zinc deficiency in junior high school students in Tehran City in 1997. This cross-sectional study was performed on 881 students (452 males and 429 females) with the mean age of 13.2+/-1.0 yr, who were selected by multistage random sampling method. Plasma, erythrocyte, and hair zinc levels were assayed by flame atomic absorption spectrophotometry. Anthropometric and demographic characteristics were measured and recorded on a questionnaire. Dietary intakes were evaluated by a 24-h recall method. Zinc deficiency was defined as having at least two indices from indices of erythrocyte, plasma, and hair zinc below 10 microg/mL, 100 microg/dL, and 125 microg/g of hair, respectively. The results showed that zinc deficiency prevalence was 31.1% (confidence interval: 28-34.4%). Zinc deficiency was 65%, 49%, and 1.3% based on plasma, erythrocyte, and hair zinc levels, respectively. The mean +/- SD for plasma, erythrocyte, and hair zinc concentration, height-for-age, as well as weight-for-age Z scores were 95.2+/-17.7 microg/dL, 10.3+/-2.3 microg/mL, 239.4+/-54.4 microg/g, -0.40+/-0.92, and 0.12+/-0.91, respectively. As for dietary intake compared with the RDA, 50% of the subjects consumed less than 50% of their requirement for zinc RDA based on a 24-h dietary recall. Zinc intake in subjects was 7.5+/-3.7 microg, that in boys was higher than in girls. Correlation coefficients between zinc status indices were very weak. There was neither a linear nor nonlinear relationship between biochemical parameters and nutritional zinc intake. It is concluded that almost one-third to one-half of the subjects would be considered zinc deficient.