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Is Spinach Safe for Kidney Stones? (Avoid)

Straight answer: no, Spinach is not safe for kidney stone patients tracking oxalate. Harvard measured 493 mg per 1/2 cup — that's well into the Avoid zone. This doesn't mean you can never eat it, but it does mean it shouldn't be a regular part of your diet. Occasional, small portions paired with calcium-rich foods are the realistic compromise.
✓ Medically Reviewed Based on Harvard T.H. Chan SPH oxalate data (2024) and NKF/AUA dietary guidelines.
493
mg oxalate
per serving
Food: Spinach, fresh or frozen, boiled or steamed
Serving: 1/2 cup (87 g)
Verdict: 🔴 Avoid
Per 100g: 567 mg
Data: Harvard T.H. Chan SPH (2024)
🔄 Lower-Oxalate Alternatives
🟢 Garlic
0 mg / serving
🟢 Seaweed
0 mg / serving
🟢 Seaweed
0 mg / serving
🟢 Passion Fruit or Granadilla
0 mg / serving
💡 What This Means for Your Diet

What this means: Spinach is rated Avoid (🔴). At 493 mg oxalate per serving, Spinach exceeds the 100 mg threshold. Kidney stone patients should limit or avoid this food. If you do eat it, keep portions very small, pair it with calcium, and drink extra water. Check the full food page for safer alternatives.

📊 How Spinach Compares

Among vegetables, Spinach sits well above the category average of 27 mg. For context, 219 out of 271 vegetables (80%) are rated 🟢 Safe (under 25 mg oxalate/serving). The average vegetables in our database has 27 mg oxalate per serving — which means Spinach is 1724% above the category norm. Within its specific category, Spinach ranks on the higher end for oxalate. This context matters because two 'Safe' foods can have very different oxalate levels — one might have 5 mg while another has 24 mg. Both are Safe, but the first gives you more dietary flexibility. Browse all vegetables rated Avoid to compare within the same verdict level.

❓ Related Questions

Why does the safe threshold matter?

The 25 mg per serving threshold is based on clinical guidance for kidney stone patients. Harvard's lab data (2024) provides the most reliable oxalate measurements available — no database estimates, direct lab analysis.

Can I eat this food every day?

If it's in the Safe zone (under 25 mg/serving), yes — it can be a regular part of your diet. For Caution or Avoid foods, frequency matters. Rotate them with lower-oxalate options throughout the week.

Where does the oxalate data come from?

Harvard T.H. Chan School of Public Health (2024) via the OHF database. These are direct laboratory measurements — the most reliable oxalate data available for food.

Should I also check sodium and calcium?

Yes — kidney stone risk isn't just about oxalate. High sodium increases urinary calcium (a stone promoter). Adequate dietary calcium (from food, not supplements) actually binds oxalate in your gut. Check the food's full nutrition page for the complete picture.

Spinach full page 🟢 Safe foods Avoid foods
This is dietary reference information, NOT medical advice. Talk to your doctor or a registered dietitian before changing your diet. Oxalate tolerance varies by person, stone type, and medication.