Quality improvement of saliva by chewing tapioca pearls in bubble tea drinks: a randomized experimental trial (Study on salivary C-reactive protein (CRP) and calcium (Ca) levels) [version 2; peer review: 2 approved, 1 not approved]

Background: Bubble tea drinks contain tea and tapioca pearls. Chewing tapioca pearls in bubble tea drinks may increase salivary components. Because of its proteins, inorganic components, and enzymes, saliva plays an important role in the body's defense against bacteria and viruses. This study aims to analyze the effect of chewing tapioca pearls in bubble tea drinks on salivary C-reactive protein (CRP) and calcium (Ca) levels. Methods: The inclusion criterion was 18-25 years of age. The exclusion criteria were receiving medication, using dentures, a history of dry mouth, smoking and systemic disease. In the first week of the experiment, subjects drank bubble tea with tapioca pearls for three days (intervention week). In the second week, the same subjects drank tea without pearls for three days (control week). Each subject drank the bubble tea for 5 minutes per day over 3 days. Saliva samples were collected on the first day before bubble tea consumption (pretest) and on the third day after tea consumption (posttest). Saliva collection was performed in the morning (09:00 am-12:00 pm) for 1 minute. Sixty saliva samples were collected from 15 subjects. Salivary CRP levels were measured using a commercial ELISA kit, and Ca levels were determined using semi-quantitative test strips. Results: Salivary CRP decreased significantly on the third day in the intervention group but showed no significant difference with the control group. Calcium levels increased significantly on the third day in both groups. Conclusion: Bubble tea drinks could improve the quality of saliva by decreasing salivary CRP and increasing Ca levels. Trial registration: ClinicalTrials.gov, NCT04670341 (17 th December 2020).