What drink is best for hydration? Milk is better than water.

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When you are thirsty and need a drink, which drinks are best for you? keeping you hydrated?

Sure, you can always look for a glass of water — but plain H2O isn’t the most hydrating drink out there, according to one study from St. Andrews University of Scotland which compared the hydration responses of several different beverages.

The researchers found that while the water, both still and sparkling — does a good job of quickly hydrating the body, drinks with a little sugar, fat, or protein do a better job of keeping us hydrated longer.

The reason has to do with the way our bodies respond to beverages, according to Ronald Maughan, a professor at St. Andrews Medical School and an author of the study. One factor is the volume of a given drink: the more you drink, the faster the drink empties from your stomach and is absorbed into your bloodstream, where it can dilute your body’s fluids and hydrate you.

The other factor that affects how well a drink hydrates relates to the nutrient composition of a drink. For example, milk was found to be even more hydrating than plain water because it contains lactose sugar, some protein, and some fat, all of which help slow the emptying of fluid from the stomach and maintain hydration for a longer period of time. .

Milk also has sodium, which acts like a sponge, holding water in the body and producing less urine.

The same can be said for oral rehydration solutions used to treat diarrhea. These contain small amounts of sugar, as well as sodium and potassium, It can also help promote water retention in the body.

“This study tells us a lot about what we already knew: electrolytes, such as sodium and potassium, contribute to better hydration, while calories in beverages result in slower gastric emptying and therefore a slower urine release,” said Melissa Majumdar, a registered dietitian, staff educator and spokesperson for the Academy of Nutrition and Dietetics who was not involved in the study.

But here’s where it gets tricky: Beverages with more concentrated sugars, like fruit juices or colas, aren’t necessarily as hydrating as their lower-sugar cousins. They may spend a little longer in the stomach and empty more slowly compared to plain water, but once these beverages enter the small intestine, their high concentration of sugars are diluted during a physiological process called osmosis. In effect, this process “pulls” water from the body into the small intestine to dilute the sugars in these drinks. And technically, anything inside your gut is outside your body.

Juices and sodas are not only less hydrating, but offer additional sugars and calories that won’t fill us up as much as solid foods, Majumdar explained. If the choice is between soft drinks and water to hydrate, always choose water. After all, our kidneys and liver rely on water to flush toxins out of our bodies, and water also plays a key role in maintaining skin elasticity and suppleness. It is the cheapest moisturizer you will find.

While staying hydrated is important—doing so keeps our joints lubricated, helps prevent infection, and delivers nutrients to our cells—in most situations, people don’t need to worry too much about hydration in their drinks.

“If you’re thirsty, your body will tell you to drink more,” Maughan said. But for athletes who train seriously in hot conditions with heavy sweat losses, or someone whose cognitive function may be negatively affected by working long hours without breaks to drink, hydration becomes a critical issue.

Alcohol acts as a diuretic, making you urinate more, so when it comes to alcoholic drinks, hydration will depend on the total volume of the drink. “Beer would result in less water loss than whiskey, because you’re taking in more liquid with the beer,” Maughan said. “Strong alcoholic beverages will dehydrate, diluted alcoholic beverages will not.”

When it comes to coffee, how well your coffee hydrates you will depend on how much caffeine you consume. A regular coffee with around 80 milligrams of caffeine, about what you would find in 12 oz. from Folgers house mix – would be almost as hydrating as water, according to Maughan’s research.

Consuming more than 300 mg of caffeine, or about 2-4 cups of coffee, it could cause you to lose excess fluid since caffeine causes a mild diuretic effect in the short term. This is more likely to happen with someone who doesn’t normally consume caffeine, and could be offset by adding a tablespoon or two of milk to your cup of coffee.

This story was originally published in September 2019. It has been updated.

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