The Effects of Ginger on Unstimulated Salivary Flow Rate: A Double-Blind, Randomized, Placebo-Control Trial

Abstract

Objective: To investigate the effects and safety of standardized ginger powder (SGP) on healthy volunteers’ unstimulated salivary flow rate (USFR). Materials and Methods: The present study was a single-visit, double-blind, randomized, placebo-control trial conducted in Thailand. Healthy volunteers aged 18 to 60 were eligible if they met all the criteria. They were allocated to four groups using block randomization to ensure an equal number in each group. The control group received a placebo, while the other three experimental groups received 1,000 mg, 1,500 mg, and 2,000 mg SGP, respectively. The primary outcome was the USFR, measured by a modified Schirmer test. The post USFR was measured 45 minutes after the intervention and was compared to the baseline USFR. The research assistants administered placebo and SGP capsules, identical in their appearance. The volunteers and the investigator were unaware of the assigned interventions. Results: Total of 368 volunteers were randomly assigned to four groups, each consisting of 92 participants. All three experimental groups showed a change in USFR. However, only the 2,000 mg group showed a significant increase in the USFR (mean difference 9.47 mm/5 minutes, 95% CI 3.24 to 15.71, p=0.003). Approximately 32.6% of the volunteers reported side effects, mainly gastrointestinal events, such as belching (16.3%) and mild abdominal discomfort (7.9%). Conclusion: Two thousand mg SGP significantly increased USFR, yet the effect size was modest. This may be due to the low concentration of bioactive compounds in the SGP used in the present study. All side effects were minor and temporary. Keywords: Ginger; Unstimulated salivary flow rate; Modified Schirmer test