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Does green tea cause kidney stones?

The short answer:

Drinking both green and black tea is found to be not associated with an increased risk of kidney stone formation. However, drinking iced tea could increase your risk of developing kidney stones especially if you already have a high risk of kidney stones. In this article, you will find more about drinking tea, coffee, milk, and soda and kidney stone formation.

Key facts:

  • Studies reported that drinking tea is not associated with an increased risk of kidney stone formation, especially green and black tea.
  • Some studies reported that drinking green tea could lower your risk of kidney stone formation.
  • Excessive drinking of iced tea in summer could increase your risk of having kidney stones. Especially if you were previously at a high risk of developing kidney stones.
  • You can add milk to your tea if you want to decrease its oxalate content, especially in case you prefer black tea.
  • You have to increase your water intake to save your kidneys.
  • Drinking soda increases your risk of kidney stones.
  • Milk and other dairy products are not associated with an increased risk of kidney stone formation.
  • Coffee is found to lower your risk of kidney stone development.

Content

Drinking tea and kidney stones?

Green tea and kidney stones

Black tea and kidney stones

Iced tea and kidney stones

Symptoms of kidney stones

FAQs

Drinking tea and kidney stones?

Kidney stones are a global health problem with a high recurrence rate.

About 80 % of the population reported having kidney stones which differ in size, shape, and properties.

Calcium stones represent 10 % of all kidney stones (Ref). Calcium stones often contain a mixture of calcium oxalate and phosphate. The environmental condition strongly affects the risk of kidney stone formation.

The food you eat and beverages you drink could play an important role in kidney stone formation.

A common beverage worldwide is tea.  Different types are available such as green tea, black tea iced tea. These different types vary in their effect on the formation of kidney stones.

Does green tea cause kidney stones?

Green tea is a healthy beverage with a high antioxidant content. The amount of oxalate in green tea varies according to the origin, quality, preparation, and time of harvest (Ref). leaves reaped in autumn have the highest value of oxalate than those reaped in spring.

The relationship between drinking green tea and kidney stone formation (Ref):

  • Green tea extract binds with calcium oxalate. This leads to the formation of crystals with different shapes. Also, these bonds prevent calcium oxalate from clumping together in the kidney hence, preventing larger stone formation.
  • Studies showed that green tea makes calcium oxalate flatter and flatter, which are more easily broken.
  • Moreover, green tea contains a high level of epigallocatechin gallate, this substance creates a hindrance in kidney stone formation (Ref).
  • Also, the caffeine content with its diuretic action increases the urinary excretion of calcium, sodium, and magnesium (Ref). Therefore, it may help to lower your risk of stone formation.

A study published in 2019 showed that there was no evidence of an increase in kidney stone formation among those who drink green tea daily compared to non-drinker participants.

An animal study published in 2006 showed that drinking green tea leads to inhibitory action in kidney stone formation in rats.

Another animal study published in 2005 showed that treatment with green tea decreased urinary excretion of oxalates and decreased calcium oxalate formation. Researchers attributed this action to the antioxidant effect of green tea.

Also, tea contains caffeine which is reported to lower your risk of kidney stone formation (Ref).

Does black tea cause kidney stones?

In general, black tea has higher oxalate content than green tea (Ref). The amount of oxalate increases with increasing the brewing times.

The amount of oxalate in black tea is about 156 mg/200 ml. While the amount of oxalates in green tea is 80 mg/ 200 ml (Ref).

Black tea like green tea is reported to lower your risk of developing kidney stones. The polysaccharide content and the antioxidant action of tea are found to have great potential to prevent kidney stone formation.

A study showed no significant increase in the risk of kidney stone formation resulting from drinking black tea.

A 2018 study showed that the daily consumption of tea above 240 ml leads to a lower risk of kidney stone formation.

Does iced tea cause kidney stones?

Iced tea is a popular drink during summer. It contains high oxalate content.

Oxalate is a key chemical compound in kidney stone formation. As a result, drinking iced tea increases your risk of having kidney stones (Ref).

In summer, people are commonly dehydrated. Dehydration and excessive drinking of iced tea could increase your risk of having kidney stones. Therefore, drinking water could help you to avoid kidney stone formation.

Although green tea and black tea contain oxalates, However, people don’t commonly consume large amounts of hot tea.  In contrast, during summer there is a great need to increase iced tea ingestion. Iced tea represents 85 % of tea consumed in the United States (Ref).

Moreover, people are commonly dehydrated during summer due to excessive sweating. Excessive drinking of iced tea besides the dehydration state could increase your risk of having kidney stones.

Note:

In some countries, milk is commonly added to tea. As milk contains calcium, it binds with oxalates to form a calcium oxalate complex. This complex prevents oxalate absorption, thus driving tea mixed with milk could lower your risk of kidney stone formation.

Symptoms of kidney stones:

In general, kidney stones have no symptoms. However, symptoms appear when stones pass from the kidney into your ureter. This could cause obstruction of the kidney or the ureter and hence symptoms are potentiated.

Symptoms of kidney stones include:

  • Pain and irritation during urination.
  • Increase urination frequency and urgency.
  • Nausea and vomiting.
  • In some cases, you could have blood in the urine.
  • Fever if infection occurred.

FAQs

1. What kind of tea causes kidney stones?

The association between kidney stones and tea depends on the way you prepare tea. Only iced tea is reported to increase your risk of having kidney stones.

2. Can Soda Cause Kidney Stones?

Drinking soda could decrease kidney hydration. If you drink too much soda daily, of course, you will have little chance to drink water. Water is essential to hydrate your kidneys. Thus, drinking soda could affect your urinary system. The primary function of this system is to remove toxins from your body. Drinking water is critical for this process.

A study examined the association between drinking soda and kidney stone formation. This study involved 1009 individuals aged 18-75 years old. They are reported to drink about 160 ml of soft drinks per day.

  • Half of these participants were chosen randomly to stop drinking soda and the other half acted as a control group.
  • Researchers reported that: The group who stopped drinking soft drinks was found to have 6.4 % advantages of having 3 years free of kidney stones episode compared to the control group.

A large study published in 2013 involved 194095 participants and they are followed up for more than 8 years. This study showed that:

  • About 4462 cases showed kidney stones.
  • There was a 23 % higher risk of developing kidney stones for those with higher consumption of sugar-sweetened soda.
  • The incidence of kidney stones was higher with those consuming sugar-sweetened soda compared with those who consume coffee, tea, beer, and wine.

More interestingly, cola contains phosphoric acid, while other types of soft drinks don’t contain phosphoric acids. Unfortunately, several studies reported that cola due to the presence of phosphoric acid has a higher chance of causing kidney stones than other types of soft drinks (Ref 1, 2,3).

Also, diet cola that is sugar-free still has phosphoric acid and increases the risk of kidney stones.

A study showed that individuals who agreed to stop drinking soda, especially cola, cut their risk of kidney stone recurrence by about 15 %.

3. Can drinking milk cause kidney stones?

Due to the high calcium content in milk, there is a misconception that drinking milk causes kidney stones.

Actually, drinking milk or eating yogurt is not reported to increase your risk of having kidney stones.

The calcium in milk binds with oxalate in your diet before reaching your kidney. This complex prevents oxalate from absorption. This action lowers the risk of kidney stone formation in the kidney (Ref).

4. Can drinking coffee cause kidney stones?

Although caffeine intake was reported to increase urine excretion of calcium, studies showed that caffeine-containing beverages are associated with a lower risk of kidney stone formation (Ref).

Caffeine increases urine volume. Therefore, increasing the caffeine intake leads to higher urine volume. This effect leads to urine dilution, hence, it could contribute to lowering the risk of kidney stone formation (Ref).

Coffee contains an alkaloid called trigonelline. This alkaloid has a similar effect to that of caffeine on kidney stone formation. However, the amount of trigonelline alkaloid differs according to the type of coffee. It is found in greater amounts in Arabica coffee than in Robusta coffee. The amount of this alkaloid doesn’t differ in caffeinated and decaffeinated coffee (Ref).

  • A large study published in 2013 involved 194,049 participants. Results showed that there was a 26% and 16% lower risk of kidney stone formation in those who took caffeinated and decaffeinated coffee respectively.
  • A large study published in 2014 involved 217,883 participants. Researchers found similar results. Participants who consumed a larger amount of caffeine showed a lower risk of kidney stone formation.