JACKSONVILLE, Fla. — Dr. Robert Cade, who invented the sports drink Gatorade and launched a multibillion-dollar industry that the beverage continues to dominate, died Tuesday of kidney failure. He was 80.

His death was announced by the University of Florida, where he and other researchers created Gatorade in 1965 to help the school’s football players replace carbohydrates and electrolytes lost through sweat while playing in swamp-like heat.

Now sold in 80 countries in dozens of flavors, Gatorade was born thanks to a question from former Gator Coach Dwayne Douglas, Cade said in a 2005 interview with The Associated Press.

He asked, “Doctor, why don’t football players wee-wee after a game?”

“That question changed our lives,” Cade said.

Cade’s researchers determined a football player could lose up to 18 pounds — 90 to 95 percent of it water — during the three hours it takes to play a game. Players sweated away sodium and chloride and lost plasma volume and blood volume.

Using their research, and about $43 in supplies, they concocted a brew for players to drink while playing football. The first batch was not exactly a hit.

“It sort of tasted like toilet bowl cleaner,” said Dana Shires, one of the researchers.

“I guzzled it and I vomited,” Cade said.

The researchers added some sugar and some lemon juice to improve the taste. It was first tested on freshmen because Coach Ray Graves didn’t want to hurt the varsity team. Eventually, however, the use of the sports beverage spread to the Gators, who enjoyed a winning record and were known as a “second-half team” by outlasting opponents.

After the Gators beat Georgia Tech 27-12 in the Orange Bowl in 1967, Tech coach Bobby Dodd told reporters his team lost because, “We didn’t have Gatorade … that made the difference.”

Stokely-Van Camp obtained the licensing rights for Gatorade and began marketing it as the “beverage of champions.” PepsiCo Inc. now owns the brand, which has brought the university more than $110 million in royalties since 1973.

Cade said Stokely-Van Camp hated the name “Gatorade,” believing it would was too parochial, but stuck with it after tests showed consumers liked the name.

Gatorade held 80 percent of the $5.5 billion-a-year sports drink market in 2005, according to Beverage Digest. Current figures were not immediately available.

Cade said he thought the use of Gatorade would be limited to sports teams and never dreamed it would be purchased by regular consumers.

“I never thought about the commercial market,” he said. “The financial success of this stuff really surprised us.”

The researcher also said he was proud that Gatorade was based on research into what the body loses in exercise. “The other sports drinks were created by marketing companies,” he said.

Since its introduction, Cade said the formula changed very little. An artificial sweetener has replaced sugar.

Instead of the original four flavors, there are now more than 30 available in the United States and more than 50 flavors available internationally.

Born James Robert Cade in San Antonio on Sept. 26, 1927, Cade, a Navy veteran, graduated from the University of Texas at Austin and the University of Texas Southwestern Medical School in Dallas.

Cade was appointed an assistant professor in internal medicine at UF in 1961. He worked until he was 76, retiring in November 2004 from the university, where he taught medicine, saw patients and conducted research.

Cade and his wife, Mary, had six children.