When you’re thirsty and picture the most hydrating drink, you probably envision water. You’d be wrong.
A study from St. Andrews Univ. compared how hydrating different drinks were. Both still and sparkling water hydrated people quickly. But drinks with a touch of sugar, fat and protein excelled at keeping them hydrated. That means that milk left water if the dust when it came to hydration. Because of the sugar in the form of lactose, protein, fat and small amount of sodium and potassium, it takes longer for milk to exit the stomach than water. The drinker retains more water for longer.
This might make you think a sugar-heavy drink like juice or soda may be even more hydrating. However, the body tries to dilute large amounts of sugar in the intestines by pulling in water from the rest of the body via osmosis. As for tea and coffee, it all depended on their caffeine content. Caffeine is a diuretic that causes urination. The more caffeine a drink has, the more likely it is to dehydrate you. Regular coffee with 80 milligrams of caffeine is almost as hydrating as water. If you add a splash of milk to it, it may become more hydrating than water.
The study only included 72 men, which is a drawback. When a study is small it means the researchers are drawing conclusions based off of a small set of results. The participants drank 13 drinks. The drinks were still water, sparkling water, Coke, Diet Coke, Powerade, orange juice, Pedialyte, beer, coffee, hot and iced tea, full fat and skim milk. Skim milk won.
The healthiest drinks weren’t always the best at hydrating. While skim milk is excellent, other top performers are not. The results were skim milk, Pedialyte, whole fat milk, OJ, Coke, Diet Coke, iced tea, hot tea, Powerade, still water, sparkling water, beer and coffee. From this list, it’s clear that hydrating doesn’t equal healthy. On a hot day, it’s more beneficial to reach for water than a Coke, even if a Coke might make you slightly more rehydrated.
Water is generally considered necessary for organ health. And milk, even skim milk, has calories you might not want in huge amounts. Adding milk to your daily drink rotation this summer might help you stay refreshed and cool, but it shouldn’t replace your water completely.
“Milk is about 90 percent water, meaning it can be a good source of hydration, especially in the summer months where people are more at risk for dehydration,” said clinical dietitian Patricia Kolesa. “It also contains [the essential minerals] sodium and potassium, the electrolytes needed to replace what we sweat.”
Because of the size of the study, and the importance of water for other aspects of health, we wouldn’t go all in and replace water with milk. But, when you’re thirsty on a hot day, try reaching for milk instead of water. You may find yourself feeling far more refreshed!
