Most people never need to think about oxalates. They matter if you form calcium-oxalate kidney stones, where a clinician may advise moderating the highest sources and pairing them with calcium at the same meal.
The foods below are the highest sources of oxalates among the 125 foods in our database, ordered by mg per 100 g. Treat this as an orientation to which foods sit at the top of the range, not as a complete avoid-list — values vary with variety, growing conditions and preparation, and many foods have never been measured for oxalates.
The nut and seed figures here are converted from directly-measured values in the Harvard oxalate table (2023). The remaining figures are working approximations we have not yet been able to verify against a published source — oxalate data is published per serving and mostly for cooked foods, which does not convert cleanly to the raw per-100 g basis used across this site. Treat the ordering as indicative, and if you form calcium-oxalate stones, work from your clinician’s list rather than this one.
For how oxalates behave in the body, see the Oxalates compound page.
Spinach — the top-ranked source
| Total Fat | 0.39 g |
|---|---|
| Saturated Fat | 0.06 g |
| Sodium | 79 mg |
| Potassium | 558 mg |
| Total Carbohydrate | 3.63 g |
| Dietary Fiber | 2.2 g |
| Total Sugars | 0.42 g |
| Protein | 2.86 g |
Foods highest in Oxalates
- Spinach — 970.0 mg per 100g. Vitamin K, folate, iron
- Dark Chocolate (70–85%) — 700.0 mg per 100g. Iron, magnesium, copper
- Almonds — 254.0 mg per 100g. Vitamin E, magnesium, manganese
- Sweet Potato — 240.0 mg per 100g. Beta-carotene (vitamin A), vitamin C, manganese
- Cashews — 224.0 mg per 100g. Magnesium, copper, manganese
- Chia Seeds — 200.0 mg per 100g. Calcium, phosphorus, plant omega-3 (ALA)
- Beetroot — 152.0 mg per 100g. Folate, manganese, dietary nitrates
- Buckwheat — 130.0 mg per 100g. Manganese, magnesium, copper
- Peanut Butter — 120.0 mg per 100g. Niacin, vitamin E, magnesium (natural
- Pecans — 55.4 mg per 100g. Manganese, copper, zinc
- Walnuts — 41.3 mg per 100g. Copper, manganese, plant omega-3 (ALA)
- Pistachios — 31.7 mg per 100g. Vitamin B6, potassium, magnesium
- Tofu — 10.6 mg per 100g. Calcium, manganese, selenium
- Flaxseed — 2.90 mg per 100g. Thiamine, magnesium, lignans
How to reduce Oxalates in what you already eat
How to Reduce Oxalates
Soluble oxalate leaches into cooking water, so wet-cooking methods cut it far more than dry heat.
| Method | Typical reduction | How it works |
|---|---|---|
| Boiling & draining | ~30–87% | Boil leafy greens and discard the water; soluble oxalate leaches out (steaming is much weaker). |
| Pairing with calcium | absorption ↓ | Dietary calcium binds oxalate in the gut so less reaches the kidneys. |
| Soaking (legumes/grains) | modest | Reduces a portion before cooking. |
Common questions
Are oxalates bad for you? For most people, no. Oxalates occur naturally in everyday foods, and most of those highest in oxalates are foods worth eating. They matter mainly to the minority managing a specific diagnosis, which is who this list is for.
Do I need to avoid these foods? Almost certainly not, unless a clinician has advised it for a specific diagnosis. Most of the foods on this list are nutrient-dense and worth eating; the ones at the top are simply where oxalates concentrate.
Does cooking reduce oxalates? Soluble oxalate leaches into cooking water, so wet-cooking methods cut it far more than dry heat. The table above sets out the specific methods and how much each one removes.
Scientific references & clinical evidence
This guide is built on peer-reviewed research — verify the primary sources below.
