Effects of Royal Jelly Supplementation on Dry Mouth Sensation in Patients with Normal Saliva Function: A Randomised Clinical Study

Introduction: In several cases, dry mouth sensation with normal salivary function is not diagnosed as an abnormality and this condition has no standardised treatments. Moreover, it is significantly associated with psychological disorders such as depression, trait anxiety and perceived stress. Based on recent studies, daily oral royal jelly supplementation (1000 mg) for eight weeks has beneficial effects on menopausal symptoms such as anxiety. However, there are no studies on the effects of royal jelly supplementation on dry mouth sensation in patients with normal salivary function. Further, only few clinical trials have long-term follow-up greater than eight weeks.

Aim: To evaluate the effects of royal jelly tablets on dry mouth sensation in patients with normal salivary function.

Materials and Methods: This randomised, double-blind, crossover clinical trial included 15 adults with an unstimulated salivary flow of >0.1 mL/min who had a chief complaint of dry mouth sensation and those without any salivary gland disease. This study was performed at Tokyo Medical and Dental University Hospital, Tokyo, Japan, between November 2019 and April 2020. The royal jelly tablet contained 400 mg of enzyme-treated royal jelly powder and each participant received either two tablets of enzyme-treated royal jelly (800 mg) or placebo daily for 12 weeks. The Visual Analogue Scale (VAS) was used to evaluate objective dry mouth sensation and the Japanese version of the Hospital Anxiety and Depression Scale (HADS) and General Health Questionnaire 12 (GHQ-12) were applied to assess psychological status and social dysfunction. The differences in VAS, HADS and GHQ-12 scores over time between the enzyme-treated royal jelly and placebo groups were analysed using repeated-measure analysis of variance and the post-hoc paired t-test.

Results: The 4- and 12-week VAS scores between the enzyme-treated royal jelly and placebo groups significantly differed (p-value=0.041 and 0.043, respectively). The 12-week HADS and GHQ-12 scores between the enzyme-treated royal jelly tablet and placebo groups differed significantly (p-value=0.040 and 0.046, respectively). Moreover, the HADS scores of the enzyme-treated royal jelly tablet group significantly decreased.

Conclusion: Daily supplementation with enzyme-treated royal jelly (800 mg) for 12 weeks was effective against dry mouth sensation in patients with normal saliva function.