7 Common Vegetables That Can Cause Kid.ney Stones Due to High Oxalic Acid – Many Still Eat Them the Wrong Way Without Knowing

Many people believe that leafy greens are always healthy and the more you eat, the better. However, few realize that some familiar vegetables contain high levels of oxalic acid, a compound that binds with calcium in the body to form calcium oxalate stones, increasing the risk of kidney stones when consumed improperly.

Below is a list of 7 vegetables with the highest oxalic acid content—some of them may surprise you because they’re staples in daily meals.

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7. Bok Choy

Contains 133mg of oxalic acid per 100g.
This green vegetable is commonly used in soups, stir-fries, and noodle dishes. However, many people skip blanching before cooking, unknowingly consuming large amounts of oxalic acid.

Although bok choy doesn’t taste bitter, experts recommend blanching it for about 1 minute in boiling water to remove most of the acid while preserving nutrients.

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6. Garlic Scapes

Contains 151mg of oxalic acid per 100g.
Despite its fragrant aroma and frequent use in stir-fried dishes, this vegetable is not entirely “harmless” if consumed too often.

Few people blanch garlic scapes before cooking for fear of losing their flavor—but keep in mind, even as a seasoning, overconsumption can be risky.

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5. Chinese Chives

Contains 166mg of oxalic acid per 100g.
Famous for supporting male reproductive health, Chinese chives can still contribute to stone formation if not prepared properly.

To reduce risk, lightly blanch the chives before using them—it won’t affect their signature taste but will lower the acid content.

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4. Round-Leaf Spinach

Contains a whopping 606mg of oxalic acid per 100g.
This one is well-known in the nutrition world. Spinach is rich in oxalates, but many don’t realize how high the content really is. If you want to eat it, blanching is a must—this can eliminate up to 80% of the oxalic acid and help reduce the risk of stones.

3. Water Spinach (Morning Glory)

Surprisingly high: 691mg per 100g.
Many enjoy it boiled or stir-fried with garlic, rarely blanching it beforehand. Yet, the leaves contain even more oxalic acid than the stems. Improper cooking can literally mean you're "swallowing stones."

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2. Amaranth

With 1,142mg of oxalic acid per 100g, amaranth ranks among the most dangerous.
It’s a popular summer vegetable due to its ease of growing and cooking, but it must be thoroughly blanched before eating. Also, avoid using the red water released during cooking to flavor rice or soup, as it contains harmful substances for those at risk of kidney stones.

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1. Sharp-Leaf Spinach

The "king" of oxalic acid content: 1,333mg per 100g, nearly twice as much as the round-leaf variety.
This type of spinach is widely sold in supermarkets and traditional markets. If you're not careful, you may mistakenly buy the sharp-leaf kind. It should be boiled for at least 3 minutes to make it safe to eat.

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Final Note:

Experts emphasize that a diet rich in vegetables is beneficial. However, for vegetables high in oxalic acid, preparation is key. Simply blanching them before cooking can significantly reduce oxalate levels. Avoid eating these in large quantities or too frequently.

Proper preparation not only helps prevent kidney stones but also improves calcium absorption by avoiding nutrient loss to oxalates. With kidney stone rates rising across Asia, a small change in eating habits can make a big difference to your health.