Ageing and free-living daily physical activity effects on salivary beta-defensin 2 secretion

This study examined ageing and free-living daily physical activity effects on salivary human beta-defensin 2 (hBD2). A total of 168 healthy elderly and 26 healthy young volunteers underwent saliva sampling. Free-living step count, energy expenditure and activity durations at specific intensity levels (inactive, light, moderate and vigorous) were evaluated. The results show significantly lower salivary hBD2 secretion rates for elderly than for young participants (P < 0.05). Data from elderly participants were stratified by steps per day using quartiles (Q1-Q4) for distribution. Elderly in quartiles respectively showed step counts of 3145 ± 129 in Q1, 5294 ± 83 in Q2, 7001 ± 86 in Q3 and 10,236 ± 416 steps · day^-1 in Q4. In elderly participants, significant differences were found in the mean step count, energy expenditure and activity duration with increasing pedometer-determined activity quartiles. hBD2 secretion rates were significantly higher for Q2, Q3 and Q4 than for Q1 (P < 0.05). Elderly participants in Q3 had the highest hBD2 secretion. In conclusion, these results suggest that moderate physical activity in daily living improves age-related impairment of oral immune function mediated by hBD2. For oral immune function enhancement and for prevention of upper respiratory tract infections in elderly people, we recommend accumulation of more than 7000 steps · day^-1.