… That Milk is one of the best drinks to hydrate again when dehydrated? I was suprised to hear that as for me it was the “drink water” approach and in intense cases add electrolytes to the mix. Most of us have heard that drinking eight glasses of water a day to stay hydrated is the way to go, but there is surprisingly little data to support this advice.
Now, a new “beverage hydration index” provides evidence-based suggestions for how to most efficiently hydrate. The index was developed from a British study published in December that tracked how long 13 common beverages remain in the body after being consumed.
“In the last 25 years, we’ve done many studies on rehydration after exercise,” said Ronald J. Maughan, a hydration expert from Loughborough University, and lead author of the study. “We thought it was time to look at hydration in typical consumers who aren’t exercising.”
The hydration index is modeled after the well-known glycemic index, which measures how the body responds to the carbohydrate content of different foods. (The glycemic index is used to help individuals keep their glucose-insulin response under control.) The idea behind the new hydration index is that some fluids last longer in your body than others and are therefor providing more hydration to it. After all, if you drink a cup of water and then immediately excrete half that amount in your urine, you haven’t added the amount you think to your body but actually only half of it.
The British study determined the hydration index of 13 common beverages by having the participants, 72 males in their mid-20s, drink a liter of water as the standard beverage. The amount of water still remaining in subjects’ bodies two hours later (and not turned into urine) was assigned a score of 1.0. All other beverages were evaluated in a similar manner, and then scored in comparison to water. A score higher than 1.0 indicated that more of the beverage remained in the body as compared to water, while a score lower than 1.0 indicated that more had left the body.
The results showed that the following four beverages had a significantly higher hydration index than water: Oral rehydration solution (like Pedialyte), fat-free milk, whole milk and orange juice. The first three had hydration index scores around 1.5, with orange juice doing slightly better than water at 1.1. Oral rehydration solutions are specifically formulated to combat serious dehydration such as that resulting from chronic diarrhea.
“It’s a very clever, even brilliant study,” said Lawrence Armstrong, a hydration expert at the University of Connecticut and immediate past president of the American College of Sports Medicine. “It assumes that water is the optimal rehydration fluid, which is biologically correct, and then compares other fluids to water.”
Why is milk so efficient at rehydration?Most likely because it contains everything the body needs (a shy guess from my side…). The answer is: “Normally when you drink, it signals the kidneys to get rid of the extra water by producing more urine,” Dr. Maughan said. “However, when beverages contain nutrients and electrolytes like sodium and potassium, as milk does, the stomach empties more slowly with a less dramatic effect on the kidneys.”
They also found more surprising things: Drinks containing moderate amounts of caffeine and alcohol or high levels of sugar had hydration indexes no different from water. In other words, coffee and beer are not dehydrating, despite common beliefs. The study also showed that regular soda can hydrate you just as well as water, although soda contains sugar and most sports and nutrition experts do not recommend it for hydration.
So, for those of you enjoying summer: If you feel dehydrated, consider drinking milk to get some needed hydration back into your system 😉