The purpose of this study was to investigate the relation between alterations of salivary secretory immunoglobulin A (SIgA) and the occurrence of upper respiratory tract infections (URTI) in rugby football players.We examined the relationship between the onset of URTI and the daily alterations of SIgA levels in 32 male collegiate rugby football players (20.5±1.3 years) during summer training camp for 36 days.Total of 6 in 32 subjects had the appearance of URTI symptoms (18 %). SIgA secretion rate decreased significantly in the middle of training camp compared to the baseline (P＜0.05). Furthermore, SIgA secretion rate during the appearance of URTI (13.7±1.1μg/min) were significantly lower than that without symptoms (19.2±1.4 μg/min, P＜0.01). These results suggest that serial monitoring of SIgA may be useful to assess the risk status of URTI affection in athletes.

The purpose of this study was to investigate the effects of Lactobacillus gasseri OLL2809 (MG2809) intake on salivary secretory immunoglobulin A (SIgA) secretion and incidence of upper-respiratory tract infection (URTI) symptoms among college rugby athletes. Sixty-seven subjects were assigned to a MG2809 group (n = 33) or a placebo group (n = 34) using a double-blind procedure. Each subject took MG2809 or placebo tablets for 9 weeks. Resting saliva samples were collected before (0 week) and after 2, 4, 6, 8, and 9 weeks of the MG2809 intakes. A log of URTI symptoms was kept every day during the study period. Our results showed that salivary SIgA level was significantly increased at 6 weeks in the MG2809 group (p < 0.05), although the placebo group did not show significant change. The duration of URTI symptoms episode in the MG2809 group was significantly shorter than that in the placebo (p < 0.05). These results suggest that regular intake of MG2809 may enhance oral immune function mediated by SIgA and reduce the risk of URTI in athletes.