Which drink is best for hydration? Hint: It isn’t water

Updated 12:48 PM EDT, Wed September 25, 2019
Nutritionists recommend drinking milk after working out.
Ryan Bergeron/CNN
Nutritionists recommend drinking milk after working out.
Now playing
00:33
Turns out this is more hydrating than water
U.S. District Court
Now playing
02:45
Chicago police officer charged in connection to January 6 Capitol riot
CNN
Now playing
02:02
Barr's answer draws scrutiny amid new scandal
Deep State Dogs
Now playing
03:29
See how internet sleuths are hunting down insurrectionists
Vladimir Putin NBC intv
NBC
Vladimir Putin NBC intv
Now playing
04:22
Hear how Putin compared Donald Trump to Joe Biden
Georgia Secretary of State Brad Raffensperger speaks during a news conference on Wednesday, November 11, 2020, in Atlanta.
Brynn Anderson/AP
Georgia Secretary of State Brad Raffensperger speaks during a news conference on Wednesday, November 11, 2020, in Atlanta.
Now playing
02:35
Family of GA secretary of state got death threats months after election
Britain's Catherine, Duchess of Cambridge and US First Lady Jill Biden visit Connor Downs Academy in Hayle, Cornwall on the sidelines of the G7 summit on June 11, 2021. (Photo by DANIEL LEAL-OLIVAS / various sources / AFP) (Photo by DANIEL LEAL-OLIVAS/AFP via Getty Images)
Daniel Leal-Olivas/AFP/Getty Images
Britain's Catherine, Duchess of Cambridge and US First Lady Jill Biden visit Connor Downs Academy in Hayle, Cornwall on the sidelines of the G7 summit on June 11, 2021. (Photo by DANIEL LEAL-OLIVAS / various sources / AFP) (Photo by DANIEL LEAL-OLIVAS/AFP via Getty Images)
Now playing
01:26
See Jill Biden and the Duchess of Cambridge host school roundtable
Austin-Travis County EMS
Now playing
00:45
Video: Boat dangling from the edge of dam rescued
NEW YORK, NEW YORK - JANUARY 28: People walk by a GameStop store in Brooklyn on January 28, 2021 in New York City. Markets continue a volatile streak with the Dow Jones Industrial Average rising over 500 points in morning trading following yesterdays losses. Shares of the video game retailer GameStop plunged. (Photo by Spencer Platt/Getty Images)
Spencer Platt/Getty Images
NEW YORK, NEW YORK - JANUARY 28: People walk by a GameStop store in Brooklyn on January 28, 2021 in New York City. Markets continue a volatile streak with the Dow Jones Industrial Average rising over 500 points in morning trading following yesterdays losses. Shares of the video game retailer GameStop plunged. (Photo by Spencer Platt/Getty Images)
Now playing
01:58
Fund manager says meme stock phenomenon is not a fad
Celebrity Cruises, Inc.
Now playing
02:10
'This was inevitable': CNN reporter on cruise ship passengers
Now playing
02:43
'It's a troll': CNN reporter on Jill Biden's 'love' jacket
CNN
Now playing
02:32
Schiff reacts to DOJ subpoena: Shocked ... but not surprised
Now playing
02:37
Pregnant woman's car spins out and flips after being hit by an officer
In this photo provided by the North Korean government, North Korean leader Kim Jong Un claps his hands at the ruling party congress in Pyongyang, North Korean, Sunday, Jan. 10, 2021. Kim was given a new title, "general secretary" of the ruling Workers' Party, formerly held by his late father and grandfather, state media reported Monday, Jan. 11, in what appears to a symbolic move aimed at bolstering his authority amid growing economic challenges. Independent journalists were not given access to cover the event depicted in this image distributed by the North Korean government. The content of this image is as provided and cannot be independently verified. Korean language watermark on image as provided by source reads: "KCNA" which is the abbreviation for Korean Central News Agency. (Korean Central News Agency/Korea News Service via AP)
KCNA/AP
In this photo provided by the North Korean government, North Korean leader Kim Jong Un claps his hands at the ruling party congress in Pyongyang, North Korean, Sunday, Jan. 10, 2021. Kim was given a new title, "general secretary" of the ruling Workers' Party, formerly held by his late father and grandfather, state media reported Monday, Jan. 11, in what appears to a symbolic move aimed at bolstering his authority amid growing economic challenges. Independent journalists were not given access to cover the event depicted in this image distributed by the North Korean government. The content of this image is as provided and cannot be independently verified. Korean language watermark on image as provided by source reads: "KCNA" which is the abbreviation for Korean Central News Agency. (Korean Central News Agency/Korea News Service via AP)
Now playing
02:23
How Kim Jong Un's weight could have geopolitical consequences
Now playing
02:30
Hear why state lawmaker was happy anti-vaccine doc testified
Brown Family
Now playing
02:34
State autopsy confirms what Andrew Brown Jr. family asserted for weeks
Now playing
03:37
'Time to pull the plug': Senator wants to move on from bipartisan talks
CNN —  

When you’re thirsty and in need of a drink, which beverages are best at keeping you hydrated?

Sure, you can always reach for a glass of water – but plain H20 isn’t the most hydrating beverage around, according to a study from Scotland’s St. Andrews University that compared the hydration responses of several different drinks.

The researchers found that while water – both still and sparkling –does a pretty good job of quickly hydrating the body, beverages with a little bit of sugar, fat or protein do an even better job of keeping us hydrated for longer.

The reason has 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. One factor is the volume of a given drink: The more you drink, the faster the drink empties from your stomach and gets absorbed into the bloodstream, where it can dilute the body’s fluids and hydrate you.

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

Milk also has sodium, which acts like a sponge and holds onto water in the body and results in less urine produced.

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

The most hydrating beverages, ranked

The research team at St. Andrews University tested 13 common beverages to see how they impact hydration. Here's what they found, ranked from most hydrating over a four-hour period to least.

  • Skim milk Oral rehydration solutions (like Pedialyte or Liquid I.V.) Full fat milk Orange juice ColaDiet Cola Cold tea TeaSports drink Still water Sparkling waterLagerCoffee
  • Source: The American Journal of Clinical Nutrition, Volume 103, Issue 3, March 2016, Pages 717--723

“This study tells us much of what we already knew: Electrolytes – like sodium and potassium – contribute to better hydration, while calories in beverages result in slower gastric emptying and therefore slower release of urination,” said Melissa Majumdar, a registered dietitian, personal trainer and spokeswoman for the Academy of Nutrition and Dietetics who was not involved in the study.

Sugar in moderation

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

Juice and soda are not only less hydrating, but offer extra sugars and calories that won’t fill us up as much as solid foods, explained Majumdar. If the choice is between soda and water for hydration, go with water every time. After all, our kidneys and liver depend on water to get rid of toxins in our bodies, and water also plays a key role in maintaining skin’s elasticity and suppleness. It’s the cheapest moisturizer you’ll find.

While staying hydrated is important – doing so keeps our joints lubricated, helps prevent infections, and carries nutrients to our cells – in most situations people don’t need to worry too much about how hydrating their beverages are.

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

Can beer and lattes keep me hydrated?

Alcohol acts as a diuretic, which causes you to pass more urine, so when it comes to alcoholic beverages hydration will depend on a beverage’s total volume. “Beer would result in less water loss than whiskey, because you are ingesting more fluid with beer,” Maughan said. “Strong alcoholic drinks will dehydrate, dilute alcoholic drinks will not.”

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

Consuming more than 300mg of caffeine,