Top 10 Highest-Oxalate Plant Foods
- SPINACH, BOILED, DRAINED, UNSALTED — 547.4 mg per serving
- SPINACH, RAW — 316.2 mg per serving
- BUCKWHEAT GROATS, ROASTED — 132.6 mg per serving
- WHEAT BERRIES, COOKED — 97.6 mg per serving
- BEANS, NAVY, CANNED — 96.3 mg per serving
- POTATO, BAKED, UNSALTED, FLESH & SKIN — 91.7 mg per serving
- BULGUR, COOKED — 85.9 mg per serving
- BEETS, CANNED, DRAINED — 76.4 mg per serving
- ALMONDS, OIL ROASTED, UNSALTED — 72.0 mg per serving
- POTATO, MICROWAVED (SKIN&FLESH) WITH NO SALT ADDED — 68.0 mg per serving
Dataset Snapshot
- 433 plant foods ranked
- 23 research sources
- Focus: Plant-based foods with oxalate data
🫘 Oxalate and kidney health
Most people can safely enjoy oxalate-rich plant foods without concern. However, those with a history of kidney stones should moderate intake of the highest-oxalate foods. Cooking and soaking can reduce oxalate content by 30–70%. Always consult a healthcare provider if you have kidney stone risk factors.
| # | Food | Serving | Oxalate (mg) | Source | |
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Oxalate values in mg per stated serving. Sources: Harvard School of Public Health (2008), USDA (1984), USDA Dr. Duke Phytochemical Database, Zarembski & Hodgkinson (1962), FAO Bangladesh (2014). Compiled via oxalate.org.
Frequently Asked Questions
What is oxalate?
Oxalate is a naturally occurring compound found in many plants. It can bind to calcium in the digestive tract, forming calcium oxalate crystals. For most people, this is not a health concern, but for those susceptible to kidney stones, oxalate intake may be relevant to disease management.
Should I avoid high-oxalate foods?
Most people can safely enjoy high-oxalate plant foods without concern. However, those with a personal or family history of kidney stones should moderate intake of the highest-oxalate foods and maintain adequate hydration. If you have kidney stone risk factors, consult a healthcare provider or registered dietitian for personalized guidance.
How can I reduce oxalate in foods?
Boiling, soaking, and cooking can reduce oxalate content by 30–70%, depending on the food and preparation method. For example, boiling leafy greens and discarding the cooking water significantly reduces oxalate. Combining oxalate-rich foods with calcium-rich foods can also help prevent absorption of soluble oxalate in the gut.
Which plant foods are lowest in oxalate?
Many fruits (apples, bananas, citrus), whole grains (rice, oats), and select vegetables (broccoli, cauliflower, green beans) are naturally low in oxalate. This ranking tool is designed to help you identify the best choices for your individual needs and dietary preferences.
Does oxalate affect calcium absorption?
Oxalate can bind to calcium in the digestive tract and reduce its absorption. However, the effect is modest in the context of a varied diet. Plant foods high in both calcium and oxalate (like collard greens) still contribute meaningful bioavailable calcium because oxalate doesn't bind all the calcium present. Consuming calcium-rich foods alongside oxalate-rich foods, and using cooking methods that reduce oxalate, minimises any absorption concerns.
Does spinach really cause kidney stones?
Spinach is one of the highest-oxalate foods, and people who are already prone to calcium oxalate kidney stones are generally advised to limit it. However, for people with no history of kidney stones, moderate spinach consumption does not cause kidney stones. Eating spinach with calcium-rich foods (like fortified plant milk), staying well-hydrated, and cooking and discarding the water all reduce the risk.
Can a plant-based diet increase kidney stone risk?
Research does not support the idea that plant-based diets inherently increase kidney stone risk. In fact, people who eat more plant foods tend to have fewer kidney stones overall. The key factors for kidney stone prevention are adequate hydration, sufficient dietary calcium (not restricted), and moderate sodium. Very high intakes of specific high-oxalate foods (spinach, almonds, rhubarb) combined with low fluid intake are the primary risk factors for oxalate stones.
What is the difference between soluble and insoluble oxalate?
Soluble oxalate (free oxalate) is readily absorbed from the gut and is the main dietary contributor to urinary oxalate levels. Insoluble oxalate is already bound to minerals (mainly calcium) in the food itself and passes through the gut without being absorbed. Foods high in insoluble oxalate (such as collard greens) are less concerning for kidney stone risk than foods where more of the oxalate is in soluble form.
Should I avoid nuts because of oxalate?
Most nuts have moderate-to-high oxalate, with almonds and cashews on the higher end. For people without kidney stone history, nuts are excellent plant-based foods and should not be avoided. For people with calcium oxalate stone history, moderate portions (a small handful per day) are generally acceptable, especially when eaten with calcium-rich foods. Macadamia nuts are among the lower-oxalate nut options.
Does cooking method affect oxalate levels?
Yes, significantly. Boiling vegetables in water and discarding the water removes the most oxalate (up to 50–70% in some foods). Steaming removes less than boiling. Roasting and microwaving cause minimal oxalate reduction. For high-oxalate vegetables like spinach, Swiss chard, and beet greens, boiling and draining is the most effective way to lower oxalate content before eating.
What role does hydration play in oxalate management?
Staying well-hydrated is the single most important dietary strategy for preventing kidney stones, including oxalate stones. High fluid intake dilutes urine, reducing the concentration of oxalate and calcium that would otherwise crystallise. Kidney stone guidelines generally recommend drinking enough fluids to produce at least 2 litres of urine per day. Lemon juice and citrate-containing drinks can also help prevent stone formation by increasing urinary citrate, which inhibits crystal growth.