Drinking excessive amounts of tea might cause kidney failure

The puzzling case of a 56-year-old U.S. man who suddenly developed weakness, fatigue and body aches is leading doctors to warn that massive consumption of tea may be responsible for some unexplained cases of kidney failure.

It’s being called iced-tea nephropathy by the New England Journal of Medicine, which published a letter describing the case April 1 online.

The source of the problem was an excessive amount of oxalate. The man reported that he was drinking 16 nine-ounce glasses of iced tea each day, giving him more than 1,500 mg of oxalate per day.

The Academy of Nutrition and Dietetics advises consuming no more than 40-50 mg of oxalate per day, the authors note.

“If you drink tea once or twice a day, it probably wouldn’t exceed what is the normal range for Americans. But this patient was taking 10 times that amount,” said Dr. Umbar Ghaffa of the University of Arkansas for Medical Sciences in Little Rock, a coauthor of the letter.

Consuming too much oxalate can lead to kidney stones. “But in this case there were oxalate crystals inside the kidney, and that generates an inflammatory reaction,” Ghaffar told Reuters Health. “If that’s not resolved it will cause scarring and loss of the kidney tissue. So that’s what probably was happening in this patient.”

He ultimately needed permanent dialysis because his kidney damage was so extensive.

“Usually if they’re at the stage where they need dialysis, it would be unusual for it to reverse,” said Dr. Gary Curhan, a professor of medicine at Harvard Medical School who was not involved with the case.

The irony is that previous research has suggested that “people who take tea in the usual amounts actually have a lower risk of kidney stones,” Curhan said.

“But in this case, the person was drinking huge amounts of oxalate,” he said. “I would caution people against drinking that much, but drinking a glass or two would not concern me.”

Ghaffar and her colleagues speculated that such regular excessive consumption of oxalate “may be an underrecognized cause of renal failure.”

“The summer season is coming and a lot of people use a lot of iced tea in this season,” she said. “We just want to make patients aware that too much of anything is bad.”