Oral intake of Lactobacillus pentosus strain b240 accelerates salivary immunoglobulin A secretion in the elderly: A randomized, placebo-controlled, double-blind trial

Abstract

Background: Immunoglobulin A (IgA) secretion in saliva decreases with age and may be the cause of increased vulnerability of the elderly to respiratory infections. The effect of oral intake of lactic acid bacteria on salivary secretory IgA (SIgA) in the elderly has not been reported. The objective of this study was to demonstrate the acceleration of salivary SIgA secretion by oral intake of Lactobacillus pentosus strain b240 (b240) in the elderly.

Results: A total of 80 healthy elderly individuals were randomly allocated to either an intervention (i.e., b240) or a control (i.e., placebo) group. The elderly individuals in the b240 group were given a sterile water beverage (125 mL) containing heat-killed b240 (4 × 109 cells), while those in the placebo group were given only a sterile water beverage (125 mL); both groups received their respective beverages once daily for 12 weeks. Saliva was collected before initiation of the study and every 2 weeks thereafter. Saliva flow rate and SIgA concentration were determined, and the SIgA secretion rate was calculated. The mean salivary SIgA secretion rate in the b240 group steadily increased until week 4 (exhibiting a 20% elevation relative to that at week 0), and then remained stable until week 12. Changes in SIgA secretion rate over the intervention period were significantly greater in the b240 group than in the placebo group. The treatment groups exhibited no significant differences in adverse events.

Conclusions: Oral intake of L. pentosus strain b240 for 12 weeks significantly accelerated salivary SIgA secretion, thereby indicating its potential utility in the improvement of mucosal immunity and resistance against infection in the elderly.

Figure 1

Changes in saliva flow rate. Changes in the saliva flow rate of subjects during the 12-week study with L. pentosus strain b240 (b240) beverage (closed circle) or placebo (open circle). Data are represented by mean ± SEM. The difference between the b240 and placebo groups was evaluated by multiple-factor ANOVA (factors: group, gender, period of intake, and frequency of saliva collection).

Figure 2

Changes in salivary SIgA concentration. Changes in the salivary SIgA concentration of subjects during the 12-week study with L. pentosus strain b240 (b240) beverage (closed circle) or placebo (open circle). Data are represented by mean ± SEM. The difference between the b240 and placebo groups was evaluated by multiple-factor ANOVA (factors: group, gender, period of intake, and frequency of saliva collection).

Figure 3

Changes in salivary SIgA secretion rate. Changes in the salivary SIgA secretion rate of subjects during the 12-week study with L. pentosus strain b240 (b240) beverage (closed circle) or placebo (open circle). Data are represented by mean ± SEM. The difference between the b240 and placebo groups was evaluated by multiple-factor ANOVA (factors: group, gender, period of intake, and frequency of saliva collection).

Figure 4

Flow of subjects and saliva samples through the trial. N, number of subjects; n, number of saliva samples; CV, coefficient of variation. Saliva samples were collected twice per person every 2 weeks during the 12 week period. "Affecting drug" means that the drug, such as an antihistamine, potentially affects saliva secretion. "Absence" means that the subject could not participate on the day of saliva collection due to miscellaneous reasons. "No saliva" means that the subject was present but failed to provide a saliva sample.