High-Dose Probiotic Supplementation Containing Lactobacillus casei for 7 Days Does Not Enhance Salivary Antimicrobial Protein Responses to Exertional Heat Stress Compared With Placebo

Abstract

The study aimed to determine whether high-dose probiotic supplementation containing Lactobacillus casei (L. casei) for 7 consecutive days enhances salivary antimicrobial protein (S-AMP) responses to exertional-heat stress (EHS). Eight endurance-trained male volunteers (age 26 ± 6 years, nude body mass 70.2 ± 8.8 kg, height 1.75 ± 0.05 m, VO2max 59 ± 5 ml·kg-1·min-1 [M ± SD]) completed a blinded randomized and counterbalanced crossover design. Oral supplementation of the probiotic beverage (PRO; L. casei . 1011 colony-forming units·day-1) or placebo (PLA) was consumed for 7 consecutive days before 2 hr running exercise at 60% VO2max in hot ambient conditions (34.0° C and 32% RH). Body mass and unstimulated saliva and venous blood samples were collected at baseline (7 days before EHS), pre-EHS, post-EHS (1 hr, 2 hr, and 4 hr), and at 24 hr. Saliva samples were analyzed for salivary (S) IgA, α-amylase, lysozyme, and cortisol. Plasma samples were analyzed for plasma osmolality. Body mass and plasma osmolality did not differ between trials. Saliva flow rate remained relatively constant throughout the experimental design in PRO (overall M ± SD = 601 ± 284 μl/min) and PLA (557 ± 296 μl/min). PRO did not induce significant changes in resting S-AMP responses compared with PLA (p > .05). Increases in S-IgA, S-α-amylase, and S-cortisol responses, but not S-lysozyme responses, were observed after EHS (p < .05). No main effects of trial or Time x Trial interaction were observed for S-AMP and S-cortisol responses. Supplementation of a probiotic beverage containing L. casei for 7 days before EHS does not provide any further oral-respiratory mucosal immune protection, with respect to S-AMP, over PLA.

Measurement of saliva flow rate in healthy young humans: influence of collection time and mouthrinse water temperature

“…Our results have application relevance in the valid and reliable interpretation of salivary biomarkers, providing justification for the use of any of the saliva collection times assessed (1–6 min). Furthermore, in field‐based settings, difficulties in obtaining a good quality unstimulated saliva sample are also more likely because of intervention or situation influences such as stress stimulus (exercise), dehydration, and/or environmental extremes inducing airway drying . The current findings support the use of an unstimulated saliva‐collection time of up to 6 min, which may benefit such situations, providing a sufficient sample within the collection time frame.…”

“…After the standardized breakfast, participants did not consume any foods or fluids before the first sample collection and were asked to refrain from consuming any foods or fluids for the duration of the testing occasions. Participants were trained on how to provide an unstimulated saliva sample, using the passive drool technique, into preweighed universal tubes (HR 120‐EC; A & D Instruments, Tokyo, Japan), as previously reported . After thoroughly rinsing the mouth with 30 ml of sterile water for 5 s, participants were then asked to fully empty the contents of the mouth, then lean forward and passively drool into the universal tube with no orofacial movements.…”

“…concentration and secretion rate), previously reported between studies using similar methodological approaches, may be explained, in part, by the different collection methods for unstimulated saliva and the techniques adopted, including differences in mouthrinse water temperature before saliva sample collection . The adoption of standardized saliva‐collection protocols is of fundamental importance because the majority of salivary biomarkers analysed, either for research or practitioner purposes, are reported as secretion or appearance rate, to account for changes in saliva flow rate . Bearing this in mind, the aims of the current study were to determine saliva flow rate within a range of specified collection times and after mouthrinsing with water of different temperatures.…”

Effects of Probiotic (Bacillus subtilis DE111) Supplementation on Immune Function, Hormonal Status, and Physical Performance in Division I Baseball Players

“…To date, only two manuscripts have investigated the effect of probiotic administration on resistance training adaptations. The first investigation [ 29 ] found no ergogenic benefit of a probiotic supplement on muscular strength and power following 12 weeks of circuit-resistance training which is in concert with previous work in endurance athletes reporting no effect of probiotics on performance [ 17 , 19 , 20 , 57 ]. The second study found no benefit of daily Bacillus subtilis (five billion CFU) supplementation on measures of physical performance following 10 weeks of offseason training in female Division I volleyball and soccer athletes [ 27 ].…”

Endurance exercise and gut microbiota: A review

“… Gill et al. 103 2016 8 Endurance trained males were randomly assigned to 1 of 2 groups: (i) supplementation of Lactobacillus casei (1 × 10 11 cell/day) or (ii) placebo. After treatment, individuals were exposed to EHS, which comprised of 2 h running exercise at 60%VO 2max in hot ambient conditions (34.0°C and 32%RH).…”