Is fennel high in oxalate?
Moderately. Moderate, 17 mg per 1 cup sliced
Range 17 to 17 mg across 1 study, 87 g serving
Lower-oxalate swap: Cabbage, grade A, about 3.1 mg per 1 cup chopped.
Fennel has a moderate amount of oxalate: about 17 mg per 1 cup sliced, which is 34% of the 50 mg a day many stone clinics aim for.
Boiling and draining lowers oxalate, because the soluble part leaches into the water. Compare the raw and boiled rows below.
Where this number comes from
Each row is one published measurement, converted to a 87 g serving (1 cup sliced). The grade and the range use the rows prepared the way the serving is eaten, and take the middle. How the grades work.
| Per serving | Per 100 g | Preparation | Source |
|---|---|---|---|
| 4.6 mg | 5.3 mg | Boiled (n=2) | Hönow R., Hesse A, 2002via Foods 2023;12:3201, Table 5 (CC BY 4.0) |
| 11 mg soluble only* | 12.4 mg | Raw (n=11) | Santamaria P., Elia A., Serio F., Todaro E, 1999via Foods 2023;12:3201, Table 5 (CC BY 4.0) |
| 17 mg | 19.7 mg | Raw (n=1) | Hönow R., Hesse A, 2002via Foods 2023;12:3201, Table 5 (CC BY 4.0) |
* The study measured soluble oxalate only, which understates the total, so it's shown but doesn't set the grade.
By Oliver Silen · Data checked November 2, 2026 · Not medical advice