A systematic review on oral rehydration beverages for treating exerciseassociated dehydrationPart II. The effectiveness of alternatives to carbohydrate-electrolyte drinks.

Objective: Dehydration associated with exertion is a commonly encountered condition in the first aid setting, particularly at outdoor sporting events. Part I of this back-to-back review demonstrated that commercial sports drinks can be suggested for effective restoration of fluid balance in dehydrated persons. This systematic review was undertaken to compare alternative liquids, such as milk, beer, and coconut water, with water for effective oral rehydration after prolonged exercise.

Data Sources: Cochrane Library, PubMed, and Embase were searched for relevant literature in June 2022.

Study Selection: Controlled experimental and observational studies involving adults and children were included when dehydration was induced by physical exercise and oral rehydration fluids were administered and compared with regular water. No additional food intake accompanied the rehydration drinks or water. Articles in all languages were included if an English abstract was available.

Data Extraction: The study design, study population, intervention, outcome measures, and study limitations were extracted from each included article.

Data Synthesis: Out of 3485 records, 11 studies were included comparing skim or low-fat milk, coconut water, and beer (0-5% alcohol) with water. Four studies showed that drinking skim or low-fat milk, without additional food intake, led to a statistically significant improved volume/hydration status when compared with drinking water. In three trials, no significant differences were shown at multiple timepoints for outcomes related to volume and hydration status following rehydration with fresh coconut water compared with water. Lastly, there is insufficient evidence to recommend beer for rehydration (0-5% alcohol).

Conclusions: Consuming skim or low-fat cow's milk without additional food as compared with water appears to improve volume/hydration status in persons with exercise-induced dehydration. However, evidence is of very low certainty and should be interpreted with caution.