Age-based differences in hair zinc of Vancouver preschoolers.

Marginal zinc deficiency (MZD), the subclinical stage of zinc deficiency, is common in industrialized societies. Serum zinc, the most common biomarker of zinc status, lacks sensitivity and specificity to diagnose this deficiency. Hair zinc, however, is sensitive and specific enough to detect MZD in children. Differences in hair zinc associated with age and sex have been reported. These differences have not been investigated thoroughly; therefore, interpretation of the results of hair analyses is difficult. This cross-sectional study was designed to examine the hair zinc status of a group of Vancouver preschoolers (24-71 months) and assess the age- and sex-based differences in their hair zinc. Hair samples were obtained (n = 719) and analyzed for zinc using inductively coupled plasma mass spectrometry. Our results indicated a mean hair zinc of 115 +/- 43 microg/g with 17% below the low hair zinc cutoff (70 microg/g). Boys and girls had comparable mean hair zinc, while girls had a significantly higher occurrence of low hair zinc than boys (21% vs. 12%). Children <4 years of age had significantly lower mean hair zinc and higher rate of low hair zinc compared to children > or =4. Our study provides important reference values for the hair zinc of healthy North American preschoolers.