One drink is best for hydration and it’s not water or a sports drink

While water does a decent job of hydrating the human body when we are thirsty, it’s another surprising beverage that keeps dehydration at bay for longer, researchers have discovered. Although still or sparkling water does hydrate the body well, other beverages containing a little fat, protein and sugar actually keep humans hydrated for longer – and a glass of milk comes out top for longer-term quenching.

A research study by Scotland’s St. Andrews University compared the hydration responses of several different drinks, and it found milk to be “more hydrating than water”. It’s all to do with “how our bodies respond to beverages”, according to Ronald Maughan, a professor at St. Andrews’ School of Medicine – and the study’s author. The more fluid you drink, the faster it gets absorbed into the bloodstream via the stomach, and once it’s in the bloodstream, the drink begins to hydrate the body.

So, it has a lot to do with the volume of a drink, but also with another important factor: the drink taken in and its nutritional value, which play a role in keeping the body hydrated for longer.

With this in mind, a glass of cow’s milk, containing sugar lactose, a little protein and some fat, actually slows down the emptying of fluid from the gut – and therefore keeps hydration levels steady over a longer timeframe.

Cow’s milk also naturally contains sodium, which creates a sponge-like action holding onto water in the human body, and this creates less urine.

It’s a similar process to occasionally using rehydration sachets, electrolytes, to treat diarrhoea after an illness or bout of food poisoning.

Electrolytes contain sodium and potassium plus small amounts of sugar, promoting water retention at a time when it’s needed to combat dehydration.

Melissa Majumdar is a registered dietitian, personal trainer and spokeswoman for the Academy of Nutrition and Dietetics, she was not involved in this study, but has commented on the results. 

Melissa said: “Electrolytes – like sodium and potassium – contribute to better hydration, while calories in beverages result in slower gastric emptying and therefore slower release of urination.”

Milk works as a sort of natural electrolyte, containing a nutrient-dense composition which includes vitamins, minerals and protein.

The National Dairy Council (NDC) of Ireland explained the importance of dairy milk: “It’s well-known that milk is an excellent source of calcium, which is a key nutrient for the normal growth, development and maintenance of our bones.

“In fact, 99% of the body’s calcium is found in our bones and teeth. But there’s more to milk than calcium – with just one glass providing us with 8 essential nutrients, each playing important roles for our health.”

The National Dairy Council’s website added that “the nutrients in milk contribute to the normal functioning of many processes in our bodies”.

This information on the NDC website is sourced from the EU Register of Nutrition and Health Claims made on foods.