4. Discussion
xerostomia, throat
XEROSTOMIA, SALIVATION
In a low-humidity environment, oral and throat discomfort increased with time and a single ingestion of bLF before exposure to the environment yielded a notable alleviation of the discomfort in comparison to the placebo. Although the UWSFR following bLF treatment consistently demonstrated higher values across each time point in contrast to the placebo, statistical analysis did not reveal any significant disparity between the two treatments. In addition, it is worth noting that the augmentation in UWSFR was more pronounced at earlier time points subsequent to bLF treatment than after the placebo treatment. For the inclusion of participants, a physician conducted a comprehensive assessment, ensuring their overall health status. For those with a UWSFR less than 0.1 mL/min, the diagnostic criteria for xerostomia were excluded [In this study, we employed the VAS, which was initially developed for diagnosing xerostomia, to meticulously assess distinct instances of oral and throat discomfort. It is worth noting this VAS has been validated and found to exhibit a negative correlation with salivary flow rates [The cause of discomfort due to the low-humidity environment was most likely owing to the lack of moisture in the mouth, similar to xerostomia. Therefore, the mechanism by which bLF suppresses the discomfort may involve the maintenance of moisture in the mouth. Our findings suggest three possible mechanisms involved in this maintenance. The first revolves around the possibility of increasing the salivary flow rate. The UWSFR at each time point was higher following the bLF treatment compared to the placebo treatment, albeit without achieving statistical significance. In addition, UWSFR significantly increased over shorter time intervals subsequent to bLF treatment, as opposed to the placebo treatment. These facts support the possibility of an increased UWSFR following bLF treatment. Psychological tension decreases salivation [The salivary IgA secretion rate is associated with mucosal immunity and protection against foreign substances. Our expectation was that under the conditions of a low humidity environment, alongside the UWSFR, the secretion rate would also decrease. Furthermore, we postulated that bLF administration might mitigate this decline by maintaining the salivary output. However, our observations revealed that these rates remained comparable to those observed in the placebo treatment group. The conclusions drawn from this study point towards a direct influence of bLF on oral and throat mucosa. Consequently, the mechanisms underpinning bLF’s effects are expected to be operational regardless of its delivery form, encompassing various consumable formats such as chewable and liquid products, except for completely insoluble food forms, such as enteric-coated products. In our pilot test, the concentration of bLF in saliva decreased below a few µg/mL in 2 h after its ingestion. Thus, even low concentrations of bLF may effectively suppress oral and throat discomfort caused by low humidity.In this study, we found that the ingestion of bLF suppressed subjective oral and throat discomfort due to a low-humidity environment. In addition, we discussed the possibility that bLF functions via the following mechanisms: modulating the UWSFR, saliva evaporation, and salivary wettability. However, this study had some limitations. Firstly, this method to assess discomfort is subjective because no objective method is generally used for the assessment. Therefore, the results of the subjective evaluation may have been subject to bias. Secondly, the experimental environment itself engendered physiological tension in some participants, potentially influencing the measurement outcomes. Thirdly, we did not evaluate the effects of other bLF-containing food forms than aqueous bLF solution. And finally, we could not measure the bLF concentration in the saliva after ingestion of bLF to confirm whether ingested bLF remained in the mouth. In our forthcoming studies, we intend to address these limitations and conduct a clinical trial to obtain more reliable results. Intake of bLF is beneficial for oral hygiene due to its antibacterial activity. However, knowledge regarding the other uses of bLF for oral health is limited. Based on our findings, we propose a novel use of bLF for oral and throat health that alleviates oral and throat discomfort in drying conditions as well as the possibility of its use as in easily consumable food products.