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.
A question from former Gator Coach Dwayne Douglas sparked their research, 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 during the three hours it takes to play a game. They also determined 90 to 95 percent of the weight loss was water. Plasma volume decreased by 7 percent and blood volume about 5 percent. Sodium and chloride were excreted in the sweat.
Using their research, and about $43 in supplies, they concocted a brew for players to drink while playing football.
"It sort of tasted like toilet bowl cleaner," said Dana Shires, one of the researchers who sampled the first batch.
"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, Tech coach Bobby Dodd told reporters his team lost because, "We didn't have Gatorade ... that made the difference."
Gatorade sparked a $5.5 billion a year sports drink market and held 80 percent of the market in 2005, according to Beverage Digest. Current figures were not immediately available.
Cade 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. Sugar has replaced an artificial sweetener.
Instead of the original four flavors, there are now more than 30 available in the United States and more than 50 flavors available internationally. Gatorade is now sold in 80 countries. Since 1973, UF has received more than $110 million in royalties from Gatorade.
Stokely-Van Camp initially obtained the licensing rights for Gatorade and began marketing it as the "beverage of champions."
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.
The researcher thought the use of Gatorade would be limited to sports teams and never dreamed it would be purchased by regular consumers. Gatorade is now owned by PepsiCo Inc.
"I never thought about the commercial market," Cade said. "The financial success of this stuff really surprised us."
Cade worked until he was 76, retiring in November 2004 from the university, where he taught medicine, saw patients and conducted research.
"It's harder to get up every morning," he said in a 2003 interview.
In addition to medicine, Cade's other passions are Studebaker automobiles, the violin and his church.
Cade has restored more than 50 Studebakers, often entering them in restoration contests.
An accomplished violinist, he has played with the University of Florida orchestra and still plays at church and home.
In 1991, Cade was awarded the Lutheran Church's highest honor, the Wittenburg Award for his service to the church and community.
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. He performed his internship at St. Louis City Hospital in Missouri and his residency at Parkland Medical Hospital in Dallas.
He served fellowships at Southwestern Medical School in Dallas and Cornell University Medical College in New York.
In 1961, Cade was appointed an assistant professor in internal medicine at UF.
His research included kidney disease, hypertension, exercise physiology, autism and schizophrenia.
Cade and his wife, Mary, had six children, Michael, Martha, Celia, Stephen, Emily and Phoebe.