Is Fennel Safe for Kidney Stones? (Safe)
mg oxalate
per serving
Serving: 1 bulb (218 g)
Verdict: 🟢 Safe
Per 100g: 5 mg
Data: Harvard T.H. Chan SPH (2024)
In practical terms, Fennel is a low-risk food for kidney stone patients. Its 12 mg oxalate per serving stays under the 25 mg line, so it can appear in your regular rotation without extra calculation. As always, staying hydrated and getting dietary calcium supports stone prevention.
Among vegetables, Fennel sits well below 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 Fennel is 56% below the category norm. Within its specific category, Fennel ranks among the lower-oxalate options. 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 Safe to compare within the same verdict level.
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. Applied to Fennel: 12 mg oxalate per 1 bulb — Safe per Harvard (2024).
Can I eat this food every day?
Daily eating is fine for Safe foods (under 25 mg/serving). For Caution or Avoid foods, spread them out and alternate with low-oxalate picks. The idea is keeping your weekly oxalate load manageable, not eliminating any single food. Fennel comes in at 12 mg oxalate per 1 bulb (Safe) in the measured database.
Where does the oxalate data come from?
Every oxalate figure is sourced from Harvard T.H. Chan SPH (2024), distributed via the OHF database. The values come from actual lab measurements of the foods — not from database averages or estimates. For Fennel, the measured oxalate value is 12 mg per 1 bulb (Safe).
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. Fennel comes in at 12 mg oxalate per 1 bulb (Safe) in the measured database.