Black tea not only contains caffeine, which can dehydrate the body, but a chemical called oxalate, which leads to the formation of kidney stones. Tiny kidney stones are normally expelled from the body without pain because they are so small. But when stones grow, they can cause great pain.
“For people who have a tendency to form the most common type of kidney stones, iced tea is one of the worst things to drink,” said urologist John Milner, in a news release from Loyola University Medical Center.
People often get kidney stones by not drinking enough water. In the summer, when people are more prone to dehydration, drinking iced tea can raise the risk of developing kidney stones, the release states.
One alternative may be to try iced green tea. Green tea contains less oxalate than black tea. Federal health officials recommend drinking no more than five cups daily, which is possibly unsafe.
Sources: National Institutes of Health, Loyola University Medical Center
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