Saliva insulin shows promise as a non-invasive biomarker of high carbohydrate intake and/or insulin resistance, key risk factors for metabolic dysregulation and caries.

Saliva insulin monitoring could potentially inform the planning and evaluation of interventions to prevent child obesity, diabetes and caries, without relying on self-reported measures from children, parents, child care providers or teachers.

School-based public health screening programs, which have staff and data collection infrastructure in place to regularly and systematically collect saliva during oral health screening, have opportunity to monitor saliva insulin.

This randomized controlled trial explores if saliva insulin is responsive to the kinds of obesity and caries intervention currently in progress in schools, namely drinking water intervention. Public health programs may justify adding saliva collection to protocol already in place if saliva insulin data are found to be actionable, i.e. sensitive to risk and intervention.

This randomized controlled trial explores if saliva insulin is responsive to the kinds of obesity and caries intervention currently in progress in schools, namely drinking water intervention.

The specific aims of this randomized controlled trial are to:

Determine if the standard serving (500 ml) of drinking water normalizes saliva insulin to a greater extent, within 60 min, than no beverage or a standard serving (200 ml) apple juice in elementary school age children.

Determine if, in line with lower saliva insulin, 500 ml drinking water significantly alters macronutrient metabolism, within 60 min, relative to no beverage or 200 ml apple juice.

Determine if 500 ml drinking water reduces caries risk factors, improves saliva osmolality, pH, buffering capacity and immune response to a greater extent, within 60 min, than no beverage or 200 ml apple juice.

Inclusion Criteria:

UCSF Pediatric Dental Clinic patients New patient exam or recall exams Caregiver and child speak English, Spanish or Chinese Ages 5-10 years San Francisco residents Non-acutely ill (healthy enough to attend school, no fever and no systemic conditions)

Exclusion Criteria:

Child and caregiver do not speak English, Spanish or Chinese Not a San Francisco resident Under age 5 years Over age 10 years Child unwilling to accept randomized drink assignment Child unable or unwilling to drink water or apple juice Child unable or unwilling to give saliva Child is presenting to the dental clinic for an operative procedure Acute illness, fever, infection or condition that would prevent the child from attending school No remaining space in study group (weight-specific recruitment is complete).

The participant will know what group they are assigned to as they will see and taste the assigned beverage. The investigator who assigns participants to a treatment group will not administer the beverage or collect data. The investigator who administers the beverage will know the group assignment. The laboratory staff who assess the outcomes will not know the assignment.