Doctors believe that a 56-year-old Arkansas man's excessive iced tea drinking caused his kidney failure which left him on dialysis.

On May 2014, the man was admitted to John L. McClellan Memorial Veterans Hospital in Little Rock showing signs of kidney failure. During that time, doctors couldn't rule out the cause of his "remarkable" abundance of calcium oxalate crystals because he doesn't have any history of kidney disease. Then the patient told Dr. Fyed Syed and Dr. Alejandra Mena-Gutierrez that he was drinking 16 cups of glasses or a gallon of black iced tea per day, according to ABC News.

"This is the first time we've ever heard of iced tea causing kidney damage and failure," Syed and Mena-Gutierrez said. "It's certainly an interesting find for us."

Doctors believe that the man's excessive iced tea drinking has caused permanent damage.

"Usually if they're at the stage where they need dialysis, it would be unusual for it to reverse," Dr. Gary Curhan, a professor of medicine at Harvard Medical School who was not involved with the case, told Reuters Health.

Black tea is high in oxalate, and experts recommend only up to 50 milligrams of oxalate per day, equivalent to 3 or 4 cups. The man was consuming about 1,500 milligrams of oxalate per day based on his iced tea drinking consumption.

The doctors clarified that people should not avoid drinking iced tea, as there are earlier studies showing that the beverage is actually good for the kidney when consumed in moderation.

"We are not advising against tea consumption," Mena-Gutierrez told LiveScience. "If you are healthy and drink tea with moderation, it should not cause damage to your kidneys."

The medical case of the Arkansas man was published in the April 1 issue of the New England Journal of Medicine.