An Arkansas man's kidney failure has been linked to drinking excessive amount of iced tea, but don't worry if you also favor the cool beverage; he reportedly was drinking 16 glasses daily, a gallon a day.
The 56-year-old had taken himself to a Little Rock hospital last year complaining of fatigue, nausea, weakness and aches.
In the hospital, his urine was found to contain large amounts of the calcium oxalate crystals associated with kidney stones.
He had no family history of kidney stones, nor had he previously suffered from them, he told doctors.
The doctors quickly ruled out a number of causes before the patient told them of his 16-cup-a-day iced black tea habit, according to a report on the case published this week in the New England Journal of Medicine.
His condition "could not be explained by any other cause in this case," says Dr. Alejandra Mena-Gutierrez, of University of Arkansas for Medical Sciences, who treated the patient and was one of the authors of the journal study on the case.
Black tea has significant amounts of a compound known as oxalate, which can cause kidney stones, and in excessive amounts, can result in kidney failure.
"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 three to 10," researchers wrote in their report.
The average person in the United States consumes between 152 to 511 mg of oxalate a day, they reported, still higher than the 40 to 50 mg a day the Academy of Nutrition and Dietetics recommends.
In 3.3 fluid ounces of black tea — which accounts for 84 percent of the tea consumed in the United States — there can be between 50 and 100 mg of oxalate.
The Arkansas patient, who was not identified in the report, was put on kidney dialysis and may have to remain on it for life since his kidney function has not recovered, Mena-Gutierrez says.
It's an extreme case, and tea drinkers should not be too concerned, she says.
"We are not advising against tea consumption," she says. "If you are healthy and drink tea with moderation, it should not cause damage to your kidneys."
Dr. Fyed Syed, who also treated the patient and coauthored the journal piece, agreed.
"If you're having two to three cups a day, you're probably OK as long as your family doesn't have a history of kidney disease," he said.
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