A:
The best way to prevent kidney stones is to stay well hydrated. So drink plenty of water.
There is conflicting information about the safety of tea drinking if a person has a history of kidney stones.
In general, experts say you should limit tea consumption because it contains oxalate. About 80% of kidney stones are made up of calcium oxalate.
(Some sources suggest that drinking tea might decrease the risk of kidney stones. If that is true, it is probably because tea drinkers drink lots of fluid and stay well hydrated.)
It is not clear that reducing foods and beverages that are high in oxalate will help prevent kidney stones in most people. But we do know that some people with a history of kidney stones excrete high amounts of oxalate in their urine. These people should probably limit their intake of foods and beverages high in oxalate.
Even if you excrete a high amount of oxalate, drinking one or two cups of herbal or green tea is probably safe. They contain only a small amount of oxalate. If your urine oxalate level is normal, you can drink even more. (You can reduce the amount of oxalate by using a tea bag rather than loose tea leaves for brewing.)
Black tea has a much higher amount of oxalate than herbal and green tea. But for unknown reasons, some studies have shown less kidney stone recurrence in people who drink black tea. But until we get more definitive evidence, its probably best to avoid black tea.
