I have heard that many people say that black tea is not very good for our kidney function. Some say that black tea can cause kidney stones. Since I am also a black tea lover who drinks tea every day, I needed to clarify the relationship between black tea and kidney function. Otherwise, I might be damaging my kidneys without even knowing. Also, having proper kidney function is vital for our health.
Black tea is a drink that is highly concentrated with oxalate. Oxalate can cause kidney stones if taken in high doses. However, regularly drinking black tea in moderation will not harm your kidney function unless you drink a gallon of black tea every day.
Some types of black teas have a low level of oxalates. We can drink more of these types of teas. Not only oxalate caffeine in black tea can also affect kidney function and kidney stones.
What are kidney stones?
Kidney stones are also known as renal calculi, urolithiasis, and nephrolithiasis. These are hard deposits in kidneys made up of minerals and salts [1]Kidney Stone Diet Plan and Prevention. (2020, December 4). National Kidney Foundation. https://www.kidney.org/atoz/content/diet.
They are made when our urine is more concentrated, and minerals in urine crystallized together. Our body can form kidney stones in any part of our urinary tract, from kidneys to the bladder.
What are the causes of kidney stones?
There are many reasons for kidney stones, such as diet, being overweight or obese, some supplements, medications, and medical conditions.
Diet is a primary reason for kidney stones. Following are some dietary factors that can affect your kidneys;
- Drinking less amount of water
- Following a diet high in protein, sugar, sodium
- Eating foods that can increase oxalate, cystine, uric acid, or calcium content
- Taking medicines such as diuretics and calcium-based antacids can also cause kidney stones
Why should you avoid kidney stones?
The reason why we should avoid kidney stones is that they are quite painful. Also, kidney stones can cause infections and other complications when they become lodged in the urinary tract [2]Kidney stones – Symptoms and causes. (2020, May 5). Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/kidney-stones/symptoms-causes/syc-20355755.
In this case, you might need surgery to remove the stones. But in different situations, you can pass kidney stones by drinking pain medications and drinking more water.
So, it is crucial to avoid the things that cause kidney stones and keep our kidneys healthy!
Black tea and kidney stones
Black tea has the highest content of oxalates compared to other types of teas. It is around 6mg per 1 g of black tea.
When we drink black tea, oxalates in it go to our digestive tract. These oxalates can bind with calcium and will be excreted from our body with stool or urine.
But if we drink too much black tea like a gallon, then there will be many oxalates that can make calcium oxalates, and high black tea consumption will increase calcium oxalate concentration in urine. This will cause kidney stones.
Taking around 1500 mg of oxalates per day might cause kidney stones. But an average person like ourselves only consumes around 150 – 500 mg each day, and it is safe.
Drinking more than 4 – 5 cups of black tea is generally not safe. The safe limit to avoid kidney stones and other side effects related to caffeine is 4, 5, or fewer black teacups per day.
When we drink too much black tea, it can increase the oxalate levels in urine, promoting kidney stones.
In one case in 2014, a man who drank 1 gallon of black tea every day developed kidney failure due to a high concentration of oxalates in urine.
However, drinking black tea in moderation will help you, while drinking too much will harm you.
How much black tea can a person with kidney disease drink?
A person with kidney stones can drink two or fewer 8 oz mugs of black tea drinks. This is because the safe limit of oxalates for kidney stone patients is 10mg or less.
If you have other kidney issues, the amount you can consume depends on your kidney issue’s severity and the doctor’s opinions.
If you have any kidney issues, I recommend drinking black tea after discussing it with your healthcare provider.
Caffeine and kidney stones
Black tea has about 47mg of caffeine in 1 cup of black tea. If we drink too many caffeine-containing beverages, it can damage our kidneys and lead to kidney stones.
But there is no problem drinking black tea in moderation, such as less than or equal to 4 – 5 cups a day.
What types of black tea are good for kidneys?
Not all black teas have a high level of caffeine and oxalates that affect your kidneys. Some milder black tea options are suitable for your kidneys. Black tea has other beneficial compounds, such as antioxidants, that can boost our health.
- Darjeeling Tea
Darjeeling tea from India is known for its flavor, color, and even processing method. This tea has a light, floral and fruity taste.
You can best enjoy this tea without any milk or sugar due to its flavor. One cup of Darjeeling tea has about 9 mg of oxalates [3]Charrier, M. J., Savage, G. P., & Vanhanen, L. (2002). Oxalate content and calcium binding capacity of tea and herbal teas. Asia Pacific journal of clinical nutrition, 11(4), 298–301. https://doi.org/10.1046/j.1440-6047.2002.00294.x. So, it is entirely safe to drink about 3-4 cups or less of this fantastic flavored tea in a day.
- Earl Grey tea
Earl Grey tea is another type of black tea that has a heavenly flavor.
This tea is flavored with natural and artificial citrus flavors. It is the most known flavored black tea in the West.
This tea has about 4 mg of oxalate per one cup of tea [4]Charrier, M. J., Savage, G. P., & Vanhanen, L. (2002). Oxalate content and calcium binding capacity of tea and herbal teas. Asia Pacific journal of clinical nutrition, 11(4), 298–301. https://doi.org/10.1046/j.1440-6047.2002.00294.x. So, it is generally safer than Darjeeling tea about the oxalate content.
In my opinion, it will be the right choice if someone with kidney stones wants to drink their most essential black tea.
- Lapsang souchong
Lapsang black tea is another type of black tea that is refreshing and has an earthy flavor. This tea has a flavor that is a combination of whisky, smoky, and tobacco flavors and it’s coming from China.
Lapsang tea also has about 9 mg of oxalates, similar to Darjeeling tea in oxalates [5]Charrier, M. J., Savage, G. P., & Vanhanen, L. (2002). Oxalate content and calcium binding capacity of tea and herbal teas. Asia Pacific journal of clinical nutrition, 11(4), 298–301. https://doi.org/10.1046/j.1440-6047.2002.00294.x. However, it is always safe to consume around 4 – 5 cups of black tea one day.
- Ceylon black tea
Ceylon black tea is one of my favorite teas in the world because I love the bold and robust flavor of Ceylon black tea.
The Lipton brand of Ceylon black tea has only 6 mg of oxalates [6]Charrier, M. J., Savage, G. P., & Vanhanen, L. (2002). Oxalate content and calcium binding capacity of tea and herbal teas. Asia Pacific journal of clinical nutrition, 11(4), 298–301. https://doi.org/10.1046/j.1440-6047.2002.00294.x. You can drink this flavorful tea in moderation every day.
What are the other foods that have high oxalate content?
Generally, black tea has less oxalate content compared to other foods. However, plant sources have high oxalate content because oxalate is bound to calcium to get rid of excess calcium.
When we eat these foods, we will also get oxalate in foods. If we take a high amount from these foods, there is a risk of getting kidney stones.
However, as I mentioned before, most high oxalate foods are also loaded with nutrients such as vegetables and fruits.
It would help if you were careful enough to balance high oxalate fruits and vegetables with low oxalate nutrient-dense foods.
Following is a list of high oxalate foods with their oxalate content;
- Soybean products- 200mg – 300mg
- Almonds (22 nuts)- 122 mg
- Potato (medium-sized baked potato) – 97 mg
- Beet (1 cup) – 152 mg
- Dates- (1 date)- 24 mg
- Raspberries (1 cup)- 48 mg
- Navy beans (1/2 cup) – 76 mg
You can eat these fruits and vegetables in moderation to have better kidney function.
Conclusion
Black tea is not an enemy of our kidney function. The main compound in black tea that affects kidney function and causes kidney stones is oxalate.
However, other foods, such as fruits and vegetables, give more oxalates than black tea. There is no harm from oxalates or any other black tea compounds if you drink it in moderation.
You can choose from the low oxalate black tea varieties mentioned above if you have any kidney issues.
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