Methods
The fluid and electrolyte balance responses after ingestion of four commonly consumed and commercially available beverages were tested in young and older volunteers. The beverages were: still water (as control); fruit juice with a moderate carbohydrate and potassium content; a sport drink with moderate carbohydrate and sodium content (S); and a low fat 1% milk with moderate carbohydrate, protein, and sodium and potassium content. The test beverages were specifically chosen with an energy content in a range of 230-350 kcal/L (except for water) and provided either sodium, potassium, or a mix of electrolyte content (Table 