The most common type of kidney stone is a calcium oxalate stone, which forms when calcium combines with oxalate in the urinary tract and travels to the kidneys. Because some varieties of hot tea are classified as high-oxalate foods, drinking too much hot tea can increase your risk of developing calcium oxalate kidney stones.
Physiology
A kidney stone is defined as a hard mass that develops from crystals that separate from your urine. Normally, your urine contains various chemicals that inhibit crystals form separating, preventing the formation of kidney stones. If your urine contains too much of a particular substance, such as oxalate, it makes it difficult for the chemicals in your urine to inhibit stone formation. Drinking excess amounts of tea contributes to the amount of oxalate in your urinary tract.
Low Oxalate Diet
If you are prone to developing calcium oxalate kidney stones, your doctor or dietitian may recommend a low-oxalate diet. Generally, people on a low-oxalate diet can consume between 40 and 50 mg of oxalate per day. This includes the oxalate found in the foods you eat as well as in the tea you drink.
Oxalate Content of Tea
Black teas are classified as a high-oxalate beverage, which means they contain more than 10 mg of oxalate per 3.5 oz serving. If you are prone to developing kidney stones, you should remove black teas from your diet. Black currant tea, rosehip tea and Matetea tea are categorized as medium-oxalate beverages. These types of teas contain between 2 and 10 mg of oxalate per 3.5 serving. While you may enjoy these teas occasionally, you should limit your intake if you are prone to kidney stones.
Green teas and herbal teas, such as peppermint, chamomile and cinnamon, contain less than 2 mg of oxalate per serving, which makes them a low-oxalate beverage. Drinking these types of hot teas can lower your risk of developing calcium oxalate stones.
Considerations
The caffeine in tea also acts as a natural diuretic, which means it triggers your body to get rid of excess water. If you drink a lot of hot tea, but do not drink adequate amounts of fluid, your body can become dehydrated. This increases the concentration of oxalate in your urinary tract, making you even more likely to develop kidney stones.
To dilute the concentration of oxalate, you not only need to decrease your tea intake, but also increase your fluid intake. Aim for 8 to 13 cups of fluid per day. It is best to choose water over sugary or other caffeinated beverages.
