This May 21, 2007 file photo shows a glass of iced tea in Concord, N.H. Doctors have traced an Arkansas man's kidney failure to an unusual cause — his habit of drinking a gallon of iced tea each day.... (Associated Press) 
 
 They ruled out several potential causes before stumbling on a reason for the 56-year-old man's kidney problems. The man's kidney function has not recovered, and he remains on dialysis, said Dr. Alejandra Mena-Gutierrez, of University of Arkansas for Medical Sciences, who treated the patient and wrote the report of his case. Tests showed that his urine had high levels of calcium oxalate crystals, which are the components of kidney stones. But the man had no family history of kidney disease, nor had he previously had kidney stones, according to the report. [7 Foods You Can Overdose On] 
 
 The man told his doctors that he drank 16 glasses of iced tea daily. Black tea — which was in the iced tea the man drank — is a rich source of oxalate, a compound that may contribute to kidney problems if consumed in high quantities. The doctors concluded that the man's excessive consumption of oxalate in the iced tea likely led to the kidney failure that was progressing rapidly. The average daily intake of oxalate in the United States is 152 to 511 mg per day,1,2 which is higher than that recommended by the Academy of Nutrition and Dietetics (<40 to 50 mg per day). "With 16 cups of tea daily, the patient's daily consumption of oxalate was more than 1500 mg — a level that is higher than the average American intake by a factor of approximately 3 to 10," they wrote. It's being called iced-tea nephropathy by the New England Journal of Medicine, which published a letter describing the case.
– A man's kidney failure has been linked to his excessive iced tea habit—but don't worry, you're probably not approaching the danger zone. The 56-year-old Arkansas man was drinking 16 glasses of the stuff daily, amounting to a gallon every day, the AP reports. Black tea contains a lot of a compound called oxalate, which can lead to kidney issues, LiveScience reports. "With 16 cups of tea daily, the patient's daily consumption of oxalate was more than 1500mg—a level that is higher than the average American intake by a factor of approximately three to 10," say doctors, who outline his case in the New England Journal of Medicine. The man was hospitalized last May, and his urine contained lots of the calcium oxalate crystals involved in kidney stones. He was put on dialysis and he may be on it for life, doctors note. "We are not advising against tea consumption," a researcher says. "If you are healthy and drink tea with moderation, it should not cause damage to your kidneys." In fact, past studies have suggested that a more reasonable amount of tea can actually fight kidney stones, an outside researcher tells Reuters. Still, many of us apparently consume too much oxalate, which can be found in spinach, chocolate, nuts, and wheat bran, among other foods. While experts don't recommend going beyond 50mg per day, the average American consumes 152mg to 511mg, researchers note. (In a comparable case, a woman died after drinking 2 gallons of Coke daily.)