Iced Tea Linked to Kidney Stones- UMass Memorial Dr. Weighs In

Friday, August 17, 2012

GoLocalWorcester Health Team

It's a summer favorite, but could iced tea increase your risk of developing kidney stones?

This is the peak season for drinking iced tea, but a Loyola University Medical Center urologist is warning the popular drink can contribute to painful kidney stones.

Iced tea contains high concentrations of oxalate, one of the key chemicals that lead to the formation of kidney stones, a common disorder of the urinary tract that affects about 10 percent of the population in the United States. "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 Dr. John Milner, assistant professor, Department of Urology, Loyola University Chicago Stritch School of Medicine.

What causes kidney stones

The most common cause of kidney stones is not drinking enough fluids. And during the summer, people can become dehydrated from sweating. Dehydration, combined with increased iced tea consumption, raises the risk of kidney stones, especially in people already at risk.

"People are told that in the summertime they should drink more fluids," Milner said. "A lot of people choose to drink more iced tea, because it is low in calories and tastes better than water. However, in terms of kidney stones, they might be doing themselves a disservice."

The issue with iced tea

Though hot tea also contains oxalate, it's hard to drink enough to cause kidney stones, Milner said. About 85 percent of tea consumed in the United States is iced, according to the Tea Association of the USA. Men are four times more likely to develop kidney stones than women, and the risk rises dramatically after age 40. Postmenopausal women with low estrogen levels and women who have had their ovaries removed also are at increased risk.

Kidney stones are small crystals that form from minerals and salt normally found in the urine in the kidneys or ureters, the small tubes that drain urine from the kidney to the bladder. Kidney stones usually are so small they are harmlessly expelled from the body. But stones sometimes grow large enough to become lodged in the ureters.

Local expert: Dr. Stephen Tosi- Chairman of the Urology Department at UMass Memorial Medical Center

GoLocalWorcester: How much iced tea is too much?

Dr. Tosi: Not to disparage the article, but there is still some controversy as to how much iced tea it would actually take to lead to an increased incidence of kidney stones. I would say that if you're enjoying two large glasses of iced tea on a hot day, you're fine. I just wouldn't be drinking a gallon of iced tea a day. So, everything in moderation.

GLW: What can you do to prevent kidney stones?

Dr Tosi: The most important thing you can do is keep a high urine output. It's shown that people who produce two liters of urine per day are at a lower risk for kidney stones. Now, I realize that is a lot to produce in a day, so you have to stay hydrated. Water is the best option, but sports drinks like Gatorade are good too. Where you can get into trouble is if you're playing sports or exercising in the hot sun and you are sweating a good amount. When you lose fluids through sweat it reduces your urine output, so it's crucial to stay hydrated.

GLW: Is there anything else we should be on the lookout for when it comes to oxalates?

Dr. Tosi: Other foods that contain oxalates are spinach, kale and kohlrabi. Also, people that take extremely high doses of Vitamin C are increasing their risk. It's good to take Vitamin C, but sometimes people take these mega doses of it. I would say 500 to 1,000 milligrams a day, tops. One of the first questions I ask someone that is a recurrent stone former is if they are taking Vitamin C and how much they are taking.