1. Introduction
xerostomia, breast milk, throat, Adverse drug reactions
XEROSTOMIA, ADVERSE DRUG REACTION, SALIVATION
To evaluate the effects of a single ingestion of bovine lactoferrin (bLF) on oral and throat conditions under a low-humidity environment. A randomized, double-blind, 2-sequence, 2-treatment, and 2-period placebo-controlled crossover trial was conducted. Healthy adult subjects orally ingested bLF dissolved in water, or placebo water, followed by exposure to low humidity (20 °C, 20% relative humidity (RH)) for 2 h. The primary endpoint was subjective oral and throat discomfort assessed by a visual analog scale (VAS), which positively correlated with the discomfort. Secondary endpoints were unstimulated whole salivary flow rate (UWSFR) and salivary immunoglobulin A (IgA) secretion rate. Overall, 40 subjects were randomly assigned to two sequences (20 each) and 34 were analyzed. The VAS values for oral and throat discomfort in the bLF treatment were significantly lower than in the placebo treatment, whereas UWSFR and IgA secretion rates were comparable between the two treatments. Adverse drug reactions were not observed. Subjective oral and throat discomfort associated with low humidity is suppressed by a single ingestion of bLF. Our findings demonstrate the novel use of bLF in a clinical situation that leverages its unique characteristics.Lactoferrin (LF) is an iron-binding glycoprotein present in bodily fluids such as mammalian breast milk, saliva, tears, and nasal secretions, exhibiting various biological functions [The amount of moisture present in the mouth is determined by the equilibrium between salivation and saliva evaporation. Loss of moisture in the mouth due to reduced salivation and/or excessive saliva evaporation can cause xerostomia [