NEW YORK (AP) — Doctors traced an Arkansas man's kidney failure to an unusual cause — his habit of drinking a gallon of iced tea each day. 
 
 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. He said he drank about 16 8-ounce cups of iced tea every day. Black tea has a chemical known to cause kidney stones or even kidney failure in excessive amounts. 
 
 "It was the only reasonable explanation," said Dr. Umbar Ghaffar of the University of Arkansas for Medical Sciences in Little Rock. She and two other doctors describe the case in Thursday's New England Journal of Medicine. 
 
 The unidentified man went to the hospital last May with nausea, weakness, fatigue and body aches. Doctors determined his kidneys were badly clogged and inflamed by the food chemical called oxalate. The man is on dialysis, perhaps for the rest of his life, Ghaffar said. 
 
 Besides black tea, oxalate is found in spinach, rhubarb, nuts, wheat bran and chocolate. In rare cases, too much oxalate can lead to kidney trouble, but often there's also a contributing intestinal problem. That didn't seem to be the case for the Arkansas man, and he had no family or personal history of kidney disease. 
 
 At 16 cups of iced black tea each day, he was taking in three to 10 times more oxalate than the average American, Ghaffar and her colleagues reported. 
 
 Federal studies suggest that, on average, U.S. adults drink a total of 10 or 11 cups of beverages per day — that's water, coffee and all other liquids combined. 
 
 Ghaffar didn't know if the man drank sugar-sweetened iced tea — the way it is usually served in the South. While he'd had diabetes, that didn't cause his kidney problems, she said. 
 
 The Arkansas case appears to be very unusual, said Dr. Randy Luciano, a Yale School of Medicine kidney specialist who has treated people with kidney damage from too much oxalate. 
 
 "I wouldn't tell people to stop drinking tea," said Luciano, who was not involved in the research. What the man drank "is a lot of tea." 
 
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 Online: 
 
 Journal: http://www.nejm.org ||||| (Reuters Health) - - 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. 
 
 The source of the problem was an excessive amount of oxalate, a compound found in many foods. Excessive amounts can also come from "juicing," having gastric bypass surgery, and by consuming foods with a lot of ascorbic acid such as beets, spinach, nuts and strawberries. 
 
 But in this case, the man reported that he was drinking 16 nine-ounce glasses of iced tea each day, giving him more than 1,500 milligrams 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, which can damage the kidney by blocking the flow of urine. "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 dialysis and remained on it 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." 
 
 SOURCE: bit.ly/1F7ZPXm New England Journal of Medicine, online April 1, 2015. ||||| After a 56-year-old man experienced kidney failure, his doctors discovered that his habit of drinking excessive amounts of iced tea every day was likely the culprit, according to a new report of his case. 
 
 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. The authors of the report stressed that moderation is key when it comes to drinking tea. 
 
 "We are not advising against tea consumption," Mena-Gutierrez said. "If you are healthy and drink tea with moderation, it should not cause damage to your kidneys." 
 
 In May 2014, the man was admitted to an Arkansas hospital, feeling weak and achy. 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. To treat his kidney failure, the doctors began dialysis. [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 man'scondition "could not be explained by any other cause in this case," Mena-Gutierrez told Live Science. 
 
 The average person in the United States consumes between 152 to 511 milligrams of oxalate a day, according to the report. This is higher than the 40 to 50 mg per day recommended by the Academy of Nutrition and Dietetics. 
 
 There are between 50 and 100 mg of oxalate per 100 ml of black tea, the researchers wrote in the report. 
 
 "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. 
 
 In another report, published in 2013 in the New England Journal of Medicine, researchers described a rare case of bone disease called skeletal fluorosis in a woman who drank a pitcher of tea made from 100 tea bags daily, for 17 years. 
 
 In the woman's case, her bone disease was likely caused by consuming too much fluoride, a mineral that is found in tea and drinking water, according to that report. 
 
 The new report was published today (April 1) in the New England Journal of Medicine. 
 
 Follow Agata Blaszczak-Boxe on Twitter. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science. ||||| To the Editor: 
 
 A 56-year-old man presented to the hospital in May 2014 with weakness, fatigue, body aches, and an elevated serum creatinine level (4.5 mg per deciliter [400 μmol per liter]). Review of his medical record indicated previous creatinine levels of 1.2 mg per deciliter (110 μmol per liter) in October 2013 and 2.5 mg per deciliter (220 μmol per liter) in February 2014. He had no proteinuria or hematuria. The urine sediment was remarkable for the presence of abundant calcium oxalate crystals. He did not have a personal history of kidney stones or any family history of kidney disease. He reported not consuming ethylene glycol. He had no malabsorptive symptoms or history of gastric surgery. On further questioning, the patient admitted to drinking sixteen 8-oz glasses of iced tea daily. Worsening renal failure with uremic symptoms necessitated the initiation of dialysis. 
 
 Figure 1. Figure 1. Renal-Biopsy Specimens. Hematoxylin and eosin staining shows calcium oxalate crystals in the renal tubules (Panel A). Polarized light microscopy shows polarizable calcium oxalate crystals (Panel B). 
 
 Owing to the rapidly progressive nature of the patient's renal failure yet normal kidney size on ultrasonography, a renal biopsy was performed, which showed many oxalate crystals, interstitial inflammation with eosinophils, and interstitial edema consistent with a diagnosis of oxalate nephropathy (Figure 1). The urinary oxalate excretion was elevated, at 99 mg (1100 μmol) in 24 hours (normal, 7 to 44 mg [80 to 490 μmol]). 
 
 Cases of acute oxalate nephropathy have been reported with Averrhoa carambola (star fruit), A. bilimbi (cucumber tree fruit), rhubarb, and peanuts. Our patient had none of the factors that have previously been associated with hyperoxaluria, such as gastric bypass surgery, overingestion of ascorbic acid, the use of “juicing,” or ethylene glycol poisoning. 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). 
 
 Black tea is a rich source of oxalate, containing 50 to 100 mg per 100 ml, a level that is similar to or higher than that in many foods considered to be rich in oxalate.3-5 About 84% of tea consumed in the United States is black tea. 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. 
 
 We speculate that oxalate nephropathy may be an underrecognized cause of renal failure. In cases of unexplained renal failure in which proteinuria is absent and abundant oxalate crystals are present in urine sediment, a thorough dietary history should be obtained, because the kidney dysfunction could be a manifestation of oxalate nephropathy from an oxalate-rich diet. The case presented here was almost certainly due to excessive consumption of iced tea. 
 
 Fahd Syed, M.D. 
 
 Central Arkansas Veterans Healthcare System, Little Rock, AR 
 
 Alejandra Mena-Gutierrez, M.D. 
 
 Umbar Ghaffar, M.D. 
 
 University of Arkansas for Medical Sciences, Little Rock, AR 
 
 Disclosure forms provided by the author are available with the full text of this article at NEJM.org.
– 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.)