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Oxalate in Tea and Coffee: Do You Need to Give Them Up?

Oxalate in Tea and Coffee: Do You Need to Give Them Up?

cup of fresh tea

Tea and coffee are favourite beverages for many, but they contain oxalates. Oxalates are natural compounds that can increase the risk of kidney stones. Understanding the oxalate content in these drinks is important for those at risk of kidney stones.

This blog will explore the oxalate content in tea and coffee, as well as their variants. This way you can begin to make informed choices about your intake of coffee and or intake of tea.

Please research and speak to a medical professional before making dietary changes. I have listed the sources I use in the Resource Library. I am not a medical practitioner, just someone trying to raise awareness.

Oxalate in Tea: Understanding the Risks

Sources of oxalate include tea. Tea is a popular drink, but it can increase the risk of kidney stones. Oxalates are natural compounds found in many plants, including tea leaves. When consumed, oxalates can bind to calcium in the gut, forming insoluble compounds that may cause kidney stones. This is particularly true for people prone to stone formation if their daily intake of oxalates is too high.

For those worried about kidney stones, it is important to understand how different types of tea affect oxalate intake. Black tea has higher oxalate levels compared to green or herbal tea. There are also differences between common types of teas and coffee depending on growing conditions and processing such as fermenting and brewing.

Watching and limiting oxalate in diets can help prevent kidney stones. Eating a balanced diet with enough plant-based calcium can also help reduce the binding of oxalates in the gut, lowering the risk of stone formation.

Oxalate Levels in Different Types of Tea

Black Tea

Black tea is known to have higher oxalate levels compared to other types of tea. Dietary intake should be monitored to avoid risk of kidney stones. The Oxalosis and Hyperoxaluria Foundation (OHF) states that black tea from multiple brands, both flavoured and unflavoured, contains 27 mg of oxalates per cup. This level is considered moderate and can contribute to the risk of kidney stones if consumed in large quantities.

Green Tea

Green tea is less processed than black tea and generally has lower oxalate levels. A cup of green tea typically contains about 21 mg of oxalates, which is considered low. This makes green tea a safer choice compared to black tea, though it still requires moderation.

Iced Tea

Iced tea, brewed for 10 minutes, contains about 17 mg of oxalates per cup. This is also considered a low oxalate level, making it a relatively safer option for those concerned about oxalate intake.

Herbal Tea (Mate)

Herbal teas, including mate, generally have much lower oxalate content. A cup of herbal mate tea contains about 14 mg of oxalates, which is low.

Herbal Tea (Variety Flavours)

Herbal teas with various flavours typically contain only about 5 mg of oxalates per cup. This very low level makes them the safest choice for those worried about kidney stones.

OHF on Tea

Here is the table without the "Average total Oxalate (mg) per 100g" and "Serving (g)" columns:


Calc Oxalate per 1 Cup Serving

Oxalate level

Tea, Black, Multiple Brands, flavoured and unflavored, with/without caffeine



Tea, Green, Multiple Brands, flavoured and unflavored



Tea, Iced, Multiple Brands, (Brewed 10 min)



Tea, Herbal, Mate



Tea, Herbal, Variety Flavors



Oxalate in Coffee: What You Need to Know

coffee from above on beans

Coffee also has oxalates, but usually at lower levels than tea.

Regular Coffee

The OHF states black coffee as having 1 mg per 100 grams or  2 mg per serving 1 cup 236 ml.

The UCI lists decaf as 2 mg per 1 cup serve.

Regular Coffee

Regular black coffee has about 1 mg of oxalate per 100 grams or 2 mg per serving (1 cup, 236 ml). This low level makes it a relatively safer option compared to black tea.

Instant Coffee

Instant coffee may have more oxalates than brewed coffee due to the processing methods used, but it still contains less oxalate compared to black tea. For example, instant coffee powder can have higher oxalate content than freshly brewed coffee.

Decaffeinated Coffee

Decaf coffee typically contains about 2 mg of oxalates per cup. This makes it another low-oxalate option for coffee lovers.

Moderate coffee consumption is generally considered safe for most people. However, those with a history of kidney stones should monitor their total oxalate intake from all foods. In addition to oxalates, coffee has other compounds, such as caffeine, which can affect kidney stone formation.

Considering Brewing Methods and Beverage Choices

The way tea and coffee are brewed can affect their oxalate content and influence their potential to cause kidney stones. For example, longer steeping times for tea can increase its oxalate concentration. Similarly, the preparation method for coffee, such as using espresso machines versus drip coffee makers, can affect oxalate levels.

Caffeinated beverages, including soft drinks, also play a role in kidney stone risk. While moderate consumption is generally safe, excessive caffeine intake can lead to dehydration, increasing urine concentration. Balancing the intake of these drinks with enough water is crucial to maintaining healthy urine and reducing the risk of stone formation.

The Role of High-Oxalate Foods and Drinks

High-oxalate foods and drinks are not the only sources of oxalates. Other common high-oxalate foods include:

  • Spinach: A leafy green vegetable high in oxalates.

  • Rhubarb: Known for its high oxalate content.

  • Beets: Another vegetable high in oxalates.

  • Certain Nuts: Almonds and cashews, for instance, are high in oxalates.

For more information like this please read my other posts on dietary oxalate. Consuming these foods in large amounts can increase the risk of kidney stones, particularly for individuals who have had calcium oxalate stones or have a family history of kidney stones.

A low-oxalate diet, limiting high-oxalate foods, can help prevent kidney stones. It is also essential to eat a balanced diet rich in nutrients and incorporate foods high in plant-based calcium to reduce oxalate absorption.

The Importance of Hydration

Fluid intake plays a crucial role in preventing kidney stones. Drinking plenty of water helps dilute oxalates and other stone-forming substances in the urine. Consuming at least 2 to 3 litres of water per day, equivalent to about 8 to 12 cups, is generally recommended. This can vary depending on individual needs and activity levels. Whereas The Daily Dozen checklist recommends 5 glasses of water daily.

Other beverages, such as apple juice and soft drinks, can also affect urine composition and contribute to stone formation. While apple juice contains some oxalates, moderate consumption is generally safe. Soft drinks, especially those containing caffeine and sugar, should be consumed in moderation.

Understanding the Role of Caffeine

Caffeine, found in both tea and coffee, has mixed effects on kidney stone risk. While caffeine increases urine volume, helping to flush out oxalates and reduce the risk of stone formation, excessive caffeine intake can lead to dehydration. Therefore, it is important to consume caffeinated beverages in moderation.

Some studies suggest that moderate coffee consumption may protect against certain types of kidney stones. However, this protective effect is not fully understood and may vary among individuals. It is important to consider individual tolerance and overall diet when evaluating the impact of caffeine on kidney stone risk.

Dietary Factors and Kidney Stone Prevention

Dietary factors significantly influence kidney stone prevention. Managing oxalate intake is crucial, but it is also important to consider other dietary components:

  • Animal Protein: A diet high in animal protein can increase the risk of stone formation. Balancing animal protein intake with plenty of fruits, vegetables, and whole grains can help maintain a healthy urinary environment.

  • Plant-Based Calcium Intake: Adequate plant-based dietary calcium is essential in preventing kidney stones. Calcium binds to oxalates in the intestines, reducing their absorption into the blood and excretion in the urine.

Maintaining a healthy body mass and engaging in regular physical activity can also reduce the risk of kidney stones. For more on foods and kidney stones read, Kidney Stones: Foods That Cause Them.

Exploring the Impact of Dietary Choices on Kidney Health

Diet affects kidney health beyond just tea and coffee consumption. For instance, high-protein foods can increase the excretion of calcium and oxalate in urine, raising the risk of kidney stones. Uric acid stones, a type of kidney stone, are influenced by diet, particularly the intake of high-purine foods like red meat and some fish.

For individuals with a history of calcium kidney stones, a balanced diet that limits high-risk foods and ensures adequate hydration and dietary calcium is crucial. Regular monitoring, such as a 24-hour urine test, can provide valuable insights into urine composition and help tailor dietary recommendations to reduce kidney stone risk.

The Role of Calcium in Preventing Kidney Stones

Calcium is vital for maintaining bone health and preventing kidney stones. Adequate dietary calcium can prevent kidney stones by binding to oxalates in the intestines, reducing their absorption into the blood and excretion in the urine.

When there is not enough calcium in the diet, more oxalate is available to form stones in the kidneys. Therefore, it’s important to consume calcium-rich foods like fortified plant-based milks and leafy greens. Balancing calcium intake ensures that it’s enough to prevent stones without overdoing it, which could harm the kidneys.

Prevention Strategies

Multiple factors affect the risk of kidney stone formation. Studies show that diet, hydration, and lifestyle play key roles in managing and reducing the risk of kidney stones. A balanced diet with limited high-oxalate foods and adequate water intake can significantly lower the risk.

Preventive measures include regular check-ups and urine tests to monitor risk factors. A 24-hour urine test can provide valuable information about urine composition, such as oxalate levels and urine volume. This data helps healthcare providers recommend personalised dietary and lifestyle changes to lower the risk of stone formation. Additionally, limiting high-protein foods and maintaining a balanced diet supports kidney health.

Summary of Oxalate in Tea and Coffee

In summary, tea and coffee both contain oxalates, which can cause kidney stones in some individuals. Knowing the oxalate content in these beverages is important for managing overall diet to prevent kidney stones.

Eating a balanced diet and staying hydrated can reduce the risk of kidney stones and maintain good urinary health. Consuming calcium-rich foods and getting regular medical monitoring and personalised dietary advice from healthcare professionals can provide extra support and guidance.


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