When you're feeling thirsty and in need of a drink, which beverages are the best for maintaining hydration?
While water is the go-to choice for many, a study conducted by Scotland's St. Andrews University suggests that plain H2O may not be the most hydrating option available. The research compared the hydration responses of various drinks and found that beverages containing small amounts of sugar, fat, or protein are more effective at keeping the body hydrated over a longer period.
Ronald Maughan, the study's author and a professor at St. Andrews' School of Medicine, explains that two factors affect the hydration properties of beverages. Firstly, the volume of the drink plays a role. The more you consume, the quicker it empties from your stomach and is absorbed into the bloodstream, diluting bodily fluids and promoting hydration.
In terms of nutrient composition, milk was found to be even more hydrating than water due to its content of lactose (sugar), protein, and fat. These components slow down the emptying of fluid from the stomach, prolonging the hydration process. Milk also contains sodium, which acts as a sponge, retaining water in the body and reducing urine production. Similarly, oral rehydration solutions used for treating diarrhea contain small amounts of sugar, sodium, and potassium, which aid water retention.
However, it's important to note that beverages with concentrated sugars, like fruit juices or colas, are not as hydrating as their lower-sugar counterparts. Although they may spend more time in the stomach and empty more slowly than water, the high sugar concentration in these drinks gets diluted during osmosis in the small intestine. This process draws water from the body to dilute the sugars, and technically, the contents of the intestine are considered outside the body.
Registered dietitian Melissa Majumdar, who was not involved in the study, explains that electrolytes such as sodium and potassium contribute to better hydration, while calories in beverages slow gastric emptying and urination. She advises opting for water over juice or soda for hydration, as the latter contain extra sugars and calories that are less filling than solid foods. Water is crucial for the kidneys and liver to eliminate toxins, and it also plays a vital role in maintaining skin elasticity and suppleness.
While it is important to stay hydrated for lubricated joints, infection prevention, and nutrient transportation, for most people, the hydrating properties of their beverages are not a major concern. Maughan notes that if you're feeling thirsty, your body will signal you to drink more. However, serious athletes training in warm conditions with high sweat loss or individuals whose cognitive function may be affected by prolonged work without beverage breaks should pay more attention to proper hydration.