Oxalates, or oxalic acid, are naturally occurring compounds found in many plant foods and beverages. While harmless for most people, a high intake can pose a risk for individuals susceptible to forming calcium oxalate kidney stones. Therefore, it is important to understand which common drinks are concentrated sources of this compound to help manage dietary intake.
Teas and Oxalate Content
Teas derived from the Camellia sinensis plant, which include black, green, and oolong varieties, are known to contain oxalates. The level of oxalate varies significantly depending on the tea type, preparation, and serving size.
Black and Green Tea
Black and green teas generally contain the highest concentrations of oxalate among common beverages. Research has shown that a typical cup of brewed black tea can contain anywhere from 3 to over 15 mg of soluble oxalate. Darker teas, including dark-fermented tea, have been found to contain higher levels of oxalate compared to green teas. For instance, a 2015 study found that dark tea had the highest oxalate levels (224 mg/200 mL), followed by black tea (156 mg/200 mL) and green tea (80 mg/200 mL). A key factor influencing the final oxalate content is steeping time; longer infusions extract more of the compound from the leaves into the beverage.
Herbal and Iced Teas
Herbal teas, or tisanes, which are not made from the Camellia sinensis plant, typically contain much lower levels of oxalates. Many popular herbal varieties, such as chamomile, peppermint, and rooibos, have very low concentrations. However, some herbal blends that include berries or citrus peels, or use specific ingredients like barley malt or mate-guarana, can have moderate to high levels. Iced teas, especially those made from black or green tea extracts, also contribute to oxalate intake. The concentration can vary depending on the type of tea used and the brewing method.
Chocolate-Based Drinks
Cocoa is a significant source of oxalate, and any beverage containing cocoa powder will have a high oxalate content.
Hot Cocoa and Chocolate Milk
Hot chocolate, hot cocoa, and chocolate milk are among the top high-oxalate beverages. The oxalate content is directly linked to the amount of cocoa or dark chocolate used. A typical cup of hot chocolate can contain around 65 mg of oxalate. Similarly, chocolate milk also contains substantial amounts.
Vegetable and Fruit Juices
While many fruit juices are low in oxalates, some vegetable and fruit juices contain considerably higher levels.
High-Oxalate Juices
- Rhubarb Nectar: Studies have identified rhubarb nectar as being exceptionally high in oxalate, with one analysis finding close to 200 mg/100 mL.
- Beetroot Juice: Beetroot juices also contain high levels, averaging 60-70 mg/100 mL, and should be limited by those following a low-oxalate diet.
- Carrot Juice: Fresh carrot juice is listed as having a moderate oxalate content.
- Tomato Juice: While typically low, some organic tomato juice preparations have been found to have higher levels.
Plant-Based Milks and Smoothies
Plant-Based Milks
Nut milks like almond, soy, cashew, and hazelnut milk are all high in oxalates due to their plant-based origin. In contrast, dairy milk is oxalate-free.
Smoothies
Smoothies can easily become high-oxalate beverages depending on the ingredients. Common high-oxalate additions include spinach, almond milk, soy milk, avocados, and raspberries.
Dark Colas and Oxalate Risk
Dark colas have been associated with an increased risk of kidney stones, but not because of a high oxalate content. The concern stems from the phosphoric acid they contain, which can affect urinary risk parameters, and the high sugar content, which has also been linked to increased stone risk. For more authoritative information on kidney stone prevention, consult resources like the American Kidney Fund: https://www.kidneyfund.org/kidney-disease/kidney-stones/
Comparison of Beverage Oxalate Levels
This table provides a quick reference for the oxalate content of various drinks. Values are approximate and can vary based on brand and preparation.
| High Oxalate (Avoid/Limit) | Moderate Oxalate (Limit) | Low Oxalate (Enjoy) |
|---|---|---|
| Black Tea (strong) | Brewed Coffee | Water |
| Green Tea (strong) | Iced Tea | Dairy Milk |
| Rhubarb Nectar | Carrot Juice | Orange Juice |
| Beetroot Juice | Cranberry Juice | Pineapple Juice |
| Chocolate Milk | Red Grape Juice | Apple Juice |
| Hot Cocoa/Ovaltine | Draft Beer | Herbal Teas (e.g., Rooibos, Chamomile) |
| Almond/Soy Milk | Tomato Juice | White/Sparkling Wine |
| Smoothies with spinach, nuts, or raspberries | Dark Cola | Distilled Alcohol |
Strategies for a Low-Oxalate Diet
For those needing to reduce their oxalate intake, here are some actionable tips:
- Pair with Calcium: Always consume high-oxalate beverages or foods with a source of calcium, such as dairy milk or cheese. Calcium binds to the oxalate in the gut, preventing its absorption.
- Stay Hydrated: Drinking plenty of water is crucial. High fluid intake helps dilute urinary oxalate, reducing the risk of stone formation. Aim for clear urine.
- Moderate Consumption: Instead of eliminating favorites, practice moderation. Enjoy smaller serving sizes less frequently.
- Choose Alternatives: Opt for low-oxalate alternatives. For example, choose herbal tea over black tea, dairy milk over nut milk, or a low-oxalate juice over beetroot or rhubarb.
- Mind Smoothie Ingredients: Be aware of what goes into your smoothies. Substitute spinach with lower-oxalate greens, and use dairy milk instead of almond or soy milk.
Conclusion
Understanding which beverages are high in oxalates is an important step for individuals managing their dietary intake to prevent calcium oxalate kidney stones. The most significant culprits include black and green teas, chocolate-based drinks, certain vegetable and fruit juices (like rhubarb and beetroot), and some plant-based milks. By being mindful of these high-oxalate beverages, employing strategies like pairing with calcium, and opting for low-oxalate alternatives, you can effectively manage your intake while still enjoying a varied diet. As always, consulting with a healthcare provider or a registered dietitian is recommended for personalized dietary advice.
