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.
PHOTO: Ryan Bergeron/CNN
Nutritionists recommend drinking milk after working out.
Now playing
00:33
Turns out this is more hydrating than water
PHOTO: CBS Evening News with Norah O'Donnell
Now playing
02:14
Governor Cuomo accuser Charlotte Bennett speaks out
Now playing
01:38
Three earthquakes trigger tsunami threat across Pacific
In this Dec. 1, 2020 file photo, Chairman of the Federal Reserve Jerome Powell appears before the Senate Banking Committee on Capitol Hill in Washington.  Powell told Congress on Wednesday, Feb. 24, 2021,  that the central bank will not begin raising interest rates until the Fed believes it has reached its goals on maximum employment  and warned that many people in the hardest hit industries will likely need to find different jobs.  (AP Photo/Susan Walsh, Pool, File)
PHOTO: Susan Walsh/AP
In this Dec. 1, 2020 file photo, Chairman of the Federal Reserve Jerome Powell appears before the Senate Banking Committee on Capitol Hill in Washington. Powell told Congress on Wednesday, Feb. 24, 2021, that the central bank will not begin raising interest rates until the Fed believes it has reached its goals on maximum employment and warned that many people in the hardest hit industries will likely need to find different jobs. (AP Photo/Susan Walsh, Pool, File)
Now playing
02:18
Jerome Powell: US economy 'some time' away from full recovery
psaki
PHOTO: CNN
psaki
Now playing
00:56
Psaki fires back at Trump testing czar over vaccine claims
PHOTO: CBS' 60 Minutes+/Getty Images
Now playing
01:45
'QAnon Shaman' says he has one regret about January 6
Now playing
02:30
Alabama governor explains why she's ending mask mandate
PHOTO: CNN
Now playing
01:35
See what security looks like outside US Capitol
PHOTO: Getty Images/CNN
Now playing
02:18
Bash: This is why key GOP senator is fighting Biden's stimulus
PHOTO: YouTube/Everyday Astronaut
Now playing
01:19
Watch SpaceX Mars prototype rocket nail landing, explode on pad
WASHINGTON, DC - JANUARY 16:  Physician to U.S. President Donald Trump Dr. Ronny Jackson listens during the daily White House press briefing at the James Brady Press Briefing Room of the White House January 16, 2018 in Washington, DC. Dr. Jackson discussed the details of President TrumpÕs physical check-up from last week.  (Photo by Alex Wong/Getty Images)
PHOTO: Alex Wong/Getty Images
WASHINGTON, DC - JANUARY 16: Physician to U.S. President Donald Trump Dr. Ronny Jackson listens during the daily White House press briefing at the James Brady Press Briefing Room of the White House January 16, 2018 in Washington, DC. Dr. Jackson discussed the details of President TrumpÕs physical check-up from last week. (Photo by Alex Wong/Getty Images)
Now playing
03:14
DOD releases scathing review of former White House physician
PHOTO: CNN/Getty
Now playing
02:10
'Highly misleading at best': Dale reacts to Pence's op-ed
PHOTO: Gov. Cuomo's office
Now playing
03:35
Gov. Andrew Cuomo addresses women's allegations
Commanding General District of Columbia National Guard Major General William J. Walker testifies before the Senate Homeland Security and Governmental Affairs/Rules and Administration hearing to examine the January 6, 2021 attack on the US Capitol on Capitol Hill on March 3, 2021 in Washington, DC. (Photo by Greg Nash / POOL / AFP) (Photo by GREG NASH/POOL/AFP via Getty Images)
PHOTO: GREG NASH/POOL/AFP via Getty Images
Commanding General District of Columbia National Guard Major General William J. Walker testifies before the Senate Homeland Security and Governmental Affairs/Rules and Administration hearing to examine the January 6, 2021 attack on the US Capitol on Capitol Hill on March 3, 2021 in Washington, DC. (Photo by Greg Nash / POOL / AFP) (Photo by GREG NASH/POOL/AFP via Getty Images)
Now playing
03:01
DC National Guard commander: 'Unusual' Pentagon restrictions slowed response to Capitol riot
Supporters of President Donald Trump hold up their phones with messages referring to the QAnon conspiracy theory at a campaign rally at Las Vegas Convention Center on February 21, 2020 in Las Vegas, Nevada.
PHOTO: Mario Tama/Getty Images
Supporters of President Donald Trump hold up their phones with messages referring to the QAnon conspiracy theory at a campaign rally at Las Vegas Convention Center on February 21, 2020 in Las Vegas, Nevada.
Now playing
03:00
Hear why QAnon supporters believe Trump will be president on March 4th
FBI Director Christopher Wray testifies before the Senate Judiciary Committee on the January 6th insurrection, in the Hart Senate Office Building on Capitol Hill in Washington, DC on March 2, 2021. (Photo by MANDEL NGAN / POOL / AFP) (Photo by MANDEL NGAN/POOL/AFP via Getty Images)
PHOTO: MANDEL NGAN/POOL/AFP via Getty Images
FBI Director Christopher Wray testifies before the Senate Judiciary Committee on the January 6th insurrection, in the Hart Senate Office Building on Capitol Hill in Washington, DC on March 2, 2021. (Photo by MANDEL NGAN / POOL / AFP) (Photo by MANDEL NGAN/POOL/AFP via Getty Images)
Now playing
02:55
Watch FBI director debunk conspiracy theories pushed by Trump supporters
WASHINGTON, DC - FEBRUARY 10: Neera Tanden, nominee for Director of the Office of Management and Budget (OMB), testifies at her confirmation hearing before the Senate Budget Committee on February 10, 2021 at the U.S. Capitol in Washington, DC. Tanden helped found the Center for American Progress, a policy research and advocacy organization and has held senior advisory positions in Democratic politics since the Clinton administration. (Photo by Anna Moneymaker-Pool/Getty Images)
PHOTO: Anna Moneymaker-Pool/Getty Images
WASHINGTON, DC - FEBRUARY 10: Neera Tanden, nominee for Director of the Office of Management and Budget (OMB), testifies at her confirmation hearing before the Senate Budget Committee on February 10, 2021 at the U.S. Capitol in Washington, DC. Tanden helped found the Center for American Progress, a policy research and advocacy organization and has held senior advisory positions in Democratic politics since the Clinton administration. (Photo by Anna Moneymaker-Pool/Getty Images)
Now playing
01:33
Neera Tanden releases statement on pulling her nomination
(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 of time.

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

Lisa Drayer is a nutritionist, an author and a CNN health and nutrition contributor.