Augmented Beverage Hydration Index Methodology for Comparing Beverage Efficacy

The Beverage Hydration Index (BHI) is a standardized, reproducible measure of short-term beverage hydration efficacy under euhydrated, resting conditions. Since its introduction by Maughan et al. in 2016, the BHI has been validated across populations and extended by our laboratory to include older adults and multiple beverage types. Specifically, the collection of serial venous samples allows for the addition of simple, but useful, physiological calculations. Here we describe methodological enhancements to the BHI protocol: the addition of change in plasma volume (ΔPV), free water clearance (C_H2O), renal osmolar clearance (C_osmol), and renal sodium clearance (C_Na⁺). These measures extend the traditional BHI methodology by elucidating vascular, renal, and sodium-handling mechanisms underlying fluid retention differences among beverages. We also describe an extended 4-hour collection period protocol adapted for older adults. A case study in healthy young adults using three commercially available beverages is provided to illustrate the utility of the augmented BHI protocol. Collectively, this refined protocol provides a practical, mechanistically informative framework for assessing beverage hydration efficacy under free-living conditions across diverse populations.