For the past couple years, coconut water has made a steady run at being the next big thing in the sports hydration business. The pitch? All natural, rich in electrolytes and low in calories.

As yoga enthusiasts, spa goers and endurance athletes caught on, so too did the nation’s biggest beverage companies.

In 2009, Pepsi acquired Amacoco, Brazil’s largest coconut water company and late last year increased its investment in O.N.E., one of the three top selling brands in this country. Later this year, they’ll team up with GNC to do their own version called Phenom. Coca-Cola couldn’t sit on the sidelines either. They invested in coconut water brand Zico, which currently holds about a 30 percent share in the $200 million US market.

Other believers with deep pockets included Madonna, Matthew McConaghey and Demi Moore, who bought a share of Vita Coco, the third big player in the American beverage landscape.

If coconut water becomes the next big thing, it will happen in the next year as the marketplace, which has existed in the niche for roughly five years in this country, starts talking to the masses.

Knowing that’s the next big challenge, Zico has signed Boston Celtics power forward Kevin Garnett as an endorser in a deal that will pay him both cash and give him an undisclosed equity stake in the company.

“I’ve always been about bettering my body,” Garnett told CNBC. “I won’t call it magic, but it’s close. It’s light on the stomach since it has low acid and it allows me to play 34 minutes in a game with some of the young stars in the league without cramping.”

Some might be skeptical given that Garnett had a deal with Gatorade up until December, but the Celtics big man speaks like a true convert. In fact, he came to Zico, not the other way around.