Is Rumex High in Oxalates? An In-Depth Look at Sorrel and Dock

January 8, 2026 •

4 min read

Studies have shown that certain Rumex species, like sorrel, can contain very high levels of total oxalates, sometimes exceeding 900 mg per 100g of wet matter, confirming that Rumex is high in oxalates. This natural compound is the source of the distinctive sour, tangy flavor found in edible varieties.

Quick Summary

Rumex plants, which include sorrel and dock, are typically high in oxalates, though levels vary based on species, plant parts, and maturity. Safe preparation can reduce the soluble oxalate content.

Key Points

High Oxalate Content: Most Rumex species, including sorrel and dock, contain significant levels of oxalates, which gives them a sour taste.
Species and Part Variation: Oxalate levels differ by species, cultivar, and plant part; mature leaves typically have higher concentrations than younger leaves.
Cooking Reduces Oxalates: Boiling Rumex and discarding the cooking water can significantly reduce its soluble oxalate content.
Health Considerations: High intake, especially for those prone to kidney stones, can lead to health risks, including potential kidney problems.
Combine with Calcium: Pairing Rumex with calcium-rich foods, such as dairy, helps bind oxalates and reduces their absorption in the body.
Moderation is Key: For most people, consuming Rumex in moderation as part of a balanced diet is safe, but excessive intake should be avoided.
Animal Toxicity: Ingesting large quantities of Rumex has caused oxalate poisoning in livestock, though this is rare in humans consuming prepared food.

The Science Behind Rumex and Oxalates

Oxalates, or oxalic acid, are natural compounds found in many plants, where they serve various functions. For humans, excessive oxalate intake can lead to health concerns, primarily the formation of calcium oxalate kidney stones in susceptible individuals. The characteristic sour taste of many Rumex species is directly attributed to their high oxalic acid content. The two main types are soluble and insoluble oxalates, with soluble oxalates being more readily absorbed by the body and thus posing a greater dietary risk.

Factors Affecting Oxalate Levels

Not all Rumex species contain the same amount of oxalate, and even within a single plant, the concentration can vary. Several factors influence the final oxalate level:

Species and Cultivar: Different Rumex species naturally accumulate oxalates at varying rates. For example, Rumex acetosa (common sorrel) is well-known for its high content, while other species may differ. Some cultivars are also bred to be lower in oxalates.
Plant Part: The concentration of oxalates is not uniform across the plant. Studies on sorrel have found that leaves, especially larger, mature ones, contain higher levels than the stems. Sprouts have also been found to be particularly high in oxalates.
Plant Maturity: As a Rumex plant matures, its oxalate content can change. Research has shown that larger, older leaves often contain higher levels of oxalates compared to younger ones.
Cooking Method: Heat and water are effective at reducing soluble oxalates. Boiling, in particular, leaches out the soluble oxalic acid, especially when the cooking water is discarded afterward.

Rumex Oxalate Levels vs. Other High-Oxalate Foods

To provide context for the oxalate levels in Rumex, it is helpful to compare them with other commonly consumed high-oxalate foods.


Food Item	Approximate Total Oxalate (mg/100g WM)	Category	Notes
*Sorrel (Rumex acetosa)*	273 - 954	Very High	Levels vary by cultivar and leaf maturity.
*Curled Dock (Rumex crispus)*	660 - 1110	Very High	Reported to be comparable to other oxalate-rich plants.
Spinach	291	High	A well-known high-oxalate vegetable.
Rhubarb	258 - 1029	Very High	Oxalates are present in stems and leaves, with the leaves being highly toxic.
Beets	500+	Very High	Beets and beet greens are a significant source of oxalates.
Nuts (Almonds)	~64	Moderate-High	Various nuts and seeds contain oxalates.

Health Implications of High Oxalate Intake

For the majority of people, moderate consumption of high-oxalate foods like Rumex does not pose a significant health risk. However, individuals with certain conditions, especially a history of kidney stones, should exercise caution. High oxalate intake can contribute to the formation of calcium oxalate crystals, which can lead to painful kidney stones. In extreme cases, consumption of very large quantities, especially by livestock, can lead to oxalate poisoning, though this is rare in humans consuming prepared food. The presence of high oxalate levels can also reduce the bioavailability of minerals, most notably calcium, as oxalates bind to them in the digestive tract.

Managing Oxalate Intake from Rumex

Fortunately, there are several ways to reduce the amount of oxalate absorbed from Rumex species, making them safer for regular consumption.

Boil and Discard Water: For mature leaves, boiling them and then discarding the water is one of the most effective ways to remove a significant portion of soluble oxalates.
Pair with Calcium-Rich Foods: Consuming Rumex with calcium-rich dairy products, such as cheese or sour cream, allows the calcium to bind with the oxalates in the digestive tract. This creates insoluble calcium oxalate, which is not absorbed by the body.
Use Younger Leaves: Younger, more immature leaves and sprouts tend to have lower, though still significant, oxalate levels and can be used in salads or for a milder flavor.
Use in Moderation: Treat Rumex as a flavorful ingredient or garnish rather than a staple vegetable. Pesto or soup preparations, which dilute the sorrel with other ingredients, contain lower oxalate levels per serving.

For additional information on the phytochemistry of Rumex species, including their many bioactive compounds beyond oxalic acid, see this comprehensive review on the topic from the National Institutes of Health.

Conclusion: Responsible Consumption of Rumex

In conclusion, the answer to "is Rumex high in oxalates?" is a definitive yes. Species like sorrel (Rumex acetosa) and curled dock (Rumex crispus) contain high levels, particularly in their mature leaves. For the average person, consuming these plants in moderation as a flavoring or in cooked dishes is safe. However, individuals with a history of kidney stones or other related conditions should be cautious and consult with a healthcare professional. By employing simple preparation techniques like boiling and combining with calcium-rich foods, the potential risks associated with oxalate intake can be effectively managed, allowing for the enjoyment of Rumex's distinctive flavor.

Frequently Asked Questions

Rumex acetosa (common sorrel) and Rumex crispus (curled dock) are known to be particularly high in oxalates, with levels affected by maturity and growing conditions.

Yes, boiling sorrel and discarding the water is an effective method for leaching out a significant portion of its soluble oxalates.

The primary risk is the formation of calcium oxalate kidney stones, especially for susceptible individuals. High oxalate intake can also interfere with mineral absorption.

Yes, sheep's sorrel is also high in oxalates and shares the characteristically sour taste with other Rumex varieties.

Both Rumex (specifically sorrel) and spinach are known for high oxalate levels. Studies have shown fresh sorrel can have comparable or even higher levels of soluble oxalates per 100g compared to spinach.

Yes, large quantities of Rumex plants, particularly in dry weight, have been documented to cause acute oxalate toxicosis in livestock like cattle and sheep.

Generally, yes. Research indicates that larger, more mature leaves of Rumex acetosa contain higher levels of total and soluble oxalates than smaller, younger leaves.