Impact of aging on human salivary gland function: A community-based study

A comprehensive evaluation of salivary flow rates and composition was undertaken in an age- and community-stratified population. A non-medicated subpopulation was used to assess the effect of 'primary aging' on salivary gland function. Unstimulated whole, parotid and submandibular/sublingual (SMSL) saliva, as well as citrate-stimulated parotid and SMSL saliva were collected from 1006 subjects. Flow rates were determined, and the total protein concentrations measured. Height and caloric intake were documented. Subjects were divided into six age groups from 35 to 75+ years old. Significant age-related decreases in the secretion rates of unstimulated whole (p < 0.001), stimulated parotid (p < 0.01) and unstimulated and stimulated SMSL (both p < 0.0001) saliva were observed in the total population. In the non-medical subpopulation, age-related decreases in salivary secretion were observed in unstimulated whole (p < 0.01) and unstimulated and stimulated SMSL (p < 0.01 and p < 0.0001, respectively). Multiple regression analysis revealed that, as well as age, caloric intake was related to unstimulated SMSL and stimulated SMSL saliva in the whole population, and height was a contributor to unstimulated whole saliva and unstimulated parotid saliva flow rate variances. In the non-medicated population, caloric intake was the significant independent variable for unstimulated and stimulated parotid secretion, as was height for unstimulated whole and SMSL flow rates. Age-related increases in the total protein concentration of unstimulated parotid (p < 0.001) and unstimulated SMSL (p < 0.05) saliva were evident in the whole population, but not in the non- mediated subgroup. These data suggest that are significant age-related alterations in salivary function.