Some Claim Birch Water Could Be the Next Super Water

— -- The latest super water making waves comes from inside the trunk of a tree, of all places.

Two companies, Sealand Birk and Byarozavik, are claiming birch tree water as a low-calorie, high-antioxidant beverage for hydration and rejuvenation. But are there health benefits?

“Birch tree water may have some health benefits in that it has electrolytes,” nutritionist Rachel Beller said on “Good Morning America.” “It also has xylitol, which may prevent tooth decay.”

The watery sap is harvested “Hunger Games”-style by tapping into a tree and draining the liquid just below the surface of the bark, which companies claim produces a drink rich in minerals and micro-nutrients.

But Beller pointed consumers to the back of one of the two brands, Byarozavik, which lists cane sugar.

“In the ingredients, it will say ‘birch tree water and cane sugar,’” she said. “Sugar, sugar, sugar – something that I don't find any of us needs to add into our diets.”

In a statement to ABC News, Byarozavik Birch Tree Water said it “adds seven grams of organic cane sugar per serving (to) preserve this highly perishable drink and allow it to get to your retailer’s shelf. Two additional grams per serving are naturally-occurring xylitol, which comes from birch trees."

Sealand Birk, in its statement to ABC News, said “BIRK does not have added cane sugar.” Its label lists 4.3 grams of sugar per four-ounce serving.

The drinks are sourced from birch trees in Eastern Europe and Scandinavia and have been around for thousands of years, but for Americans, it’s the latest hydration trend hitting the market. The bottles can be hard to come by – so far only available online and in a limited number of U.S. stores – making those who drink it anxious for its arrival.

"We were waiting for this. We are almost out,” a yoga instructor said on “GMA.”

ABC News senior medical contributor Dr. Jennifer Ashton cautioned against overestimating the drink’s benefits.

“We don’t have rigorous scientific studies that link the use of birch water to anything other than consuming a potentially hydrating beverage,” she said on “GMA.”

Editor's note: This article has been updated to note that some brands of birch water are sold in a limited number of stores in the U.S. A previous version of this article indicated that birch water is only available to U.S. consumers online.