Saliva zinc levels: potential indicators of zinc status

Mixed saliva was collected from eight adolescent females participating in a metabolic study and from 59 adolescent females participating in a nutrition survey. Zinc concentrations, protein concentrations, and zinc:protein ratios of whole mixed saliva samples and of supernatant samples, which were prepared from the mixed saliva, were determined. Zinc analyses were performed with an atomic absorption spectrophotometer equipped with a graphite furnace. Significantly (P less than 0.05) lower levels of zinc were found in the supernant samples, but not in the whole saliva samples, when the same subjects were fed 11.5 mg zinc daily rather than 14.7 mg zinc daily during the metabolic study. The mean zinc concentrations of the whole saliva and the supernatant samples collected during the survey were 173 +/- 94 (SD) and 30.5 +/- 14.8 ng/ml, respectively. The levels of zinc and protein in the whole mixed saliva (r = 0.460, P less than 0.001) and the supernatant samples (4 = 0.486, P less than 0.001) were correlated. The levels of zinc in both types of saliva samples were not correlated to serum or hair zinc levels of girls in the survey.