You’ve probably read it a million times. Tea is “bad” for kidney stones. But, there are MANY different types of tea and different types of kidney stones. What is a tea-lover to do!?
Let’s dive into the science behind tea and kidney stones.
Table of Contents
Tea & Oxalate
Tea has such a bad reputation for kidney stones because of oxalate. One cup of black tea has about 27mg of oxalate.
Does this mean a kidney stone former should NEVER have tea? Of course not!
Simply because you have kidney stones does not mean you need to limit oxalate. In fact, even people who have oxalate kidney stones may not need to be on a low oxalate diet.
How can this be!? It comes down to WHY you are making kidney stones. Most people make kidney stones because of high urine calcium. They do not necessarily have high urine oxalate. Only a 24-hour urine test can clue us into WHY you make kidney stones.
Even if you DO have high urine oxalate on a 24-hour urine test, the goal is never to completely cut oxalate out of your diet. Instead, the goal is to limit those VERY high oxalate foods. It is even more important to make sure you are eating enough calcium.
The Data: Tea & Kidney Stones
Studies show the opposite of what you might expect for tea and kidney stones. A large 2013 study found that people who drank tea at least once a day had a 20% lower risk of kidney stones compared to people who drank it less than once a week (p=0.02). (1) This confirmed what earlier studies found. (2) (3)
Yep! A LOWER risk of kidney stones for tea drinkers!
How can this be!? One likely reason is simply that tea is fluid! The single most important thing you can do to prevent kidney stones is drink plenty of fluid. Drinking a lot dilutes your urine and reduces the risk of stones. All fluids, including tea, will dilute urine.
The other likely reason is the caffeine in tea. Both tea and coffee are consistently associated with a lower risk of kidney stones. (1) (2) (3) Caffeine is a a natural diuretic. Drinks that have caffeine dilute urine even more than non-caffeinated drinks. Of course, it is important to drink extra water to replace fluid lost from this diuretic effect.
Types of Tea & Kidney Stones
Of course, all tea is not the same. There are many different kinds of tea that can impact kidney stones differently. Let’s touch on the most common teas.
Black tea is the most common type of tea. It tends to have the most oxalate at 14-27mg oxalate per cup. However, this is still not a ton of oxalate compared to 750mg oxalate per 1/2 cup cooked spinach. Or, 120mg oxalate per ounce of almonds.
Oxalate content of tea will vary based on brewing time. Tea that is seeped for more time will be higher in oxalate.
A 2021 trial found that people who drank 1 1/2 liters of black tea per day did NOT have higher urine oxalate or overall bad changes to their entire urine chemistry. (4)
Even if you have high urine oxalate, a cup or two of black tea is unlikely to cause kidney stones. Ask your dietitian what is best for you! Or, learn more from me in Kidney Stone Nutrition School!
Green tea has slightly less oxalate than black tea. One cup has about 21mg oxalate. However, reasonable amounts of green tea is unlikely to cause kidney stones.
In fact, a 2021 review suggested green tea may be especially protective against kidney stones. (5) This data is not strong enough to recommend green tea for kidney stones. However, it makes it clear people with kidney stones do not need to STOP drinking green tea.
A common home remedy for kidney stones is dandelion tea. However, there are no studies on dandelion tea and kidney stones.
I could not find a reliable source for the oxalate content of dandelion tea.
Similarly, chamomile tea is touted to be good for kidney stones. But, there are no studies on chamomile tea and kidney stones.
I could not find a reliable source for the oxalate content of chamomile tea.
There are many different kinds of herbal tea. Oxalate content will vary, but is generally lower than black or green tea. Estimates of oxalate in herbal tea vary from 5-15mg per cup.
Because herbal teas add fluid, herbal tea is likely to lower the risk of kidney stones, similar to other types of tea.
Iced tea can be made of any type of tea. Whether tea is iced or hot does not change its impact on kidney stones.
Sweet tea has quite a bit of sugar in it. One cup has nearly 20g of added sugar. (6) Sweet tea should be reserved as a treat for people with kidney stones.
Twisted Tea, Kidney Stones & Alcohol
The alcoholic drink Twisted Tea has lots of sugar. A 12oz can has 23g of added sugar. This is about half of the recommended amount for the entire day. The first ingredient in Twisted Tea is brewed black tea. So, it is safe to assume there is about the same amount of oxalate in twisted tea as black tea.
Since sugary drinks can make most types of kidney stones worse, Twisted Tea is not the best option for kidney stones.
Alcohol in general is NOT bad for kidney stones. If you enjoy an adult beverage from time to time, kidney stones are no reason to stop. The only caveat is that alcoholic drinks can add quite a bit of sugar. Learn more about alcohol and kidney stones.
Can I Drink Tea with Kidney Stones?
It is best to choose tea with little or no added sugar.
If you have high urine oxalate, ask your dietitian how much tea is right for you! Chances are, you can enjoy 1-2 cups of tea per day. Add milk to help lower oxalate absorption.
What Else Can I Drink with Kidney Stones?
A good rule of thumb is that any drink that does not have added sugar is good for kidney stones.
Some of my favorite options are:
- Unsweetened sparkling water
- Diet lemon-lime soda
- Of course, WATER!