Scientific basis for a milk permeate-based sports drink – A critical review

Fluid homeostasis is challenged during exercise when fluid availability is limited or when fluid loss is not properly replaced. Sports drinks are designed to improve hydration by stimulating fluid ingestion, reabsorption, and retention. Milk has been suggested to be an alternative hydration source to sports drinks due to its higher electrolyte concentrations and similar carbohydrate content. As milk has a high energy density and viscosity that may present gastric discomfort, attempts have been made to develop beverages from milk byproducts, such as milk permeate, that may be more efficacious for consumption during exercise. However, there is limited literature on milk permeate-based beverages for hydration or performance purposes. This review aims to identify the properties of milk that promote fluid retention, discuss how milk consumption both during or following exercise may impact performance or rehydration, respectively, and explore the scientific evidence regarding the use of milk permeate for sports drink production.