Is lettuce high in oxalate?
No. Very low, <1 mg per 1 cup shredded
Range <1 to 14 mg across 3 studies, 36 g serving
Lettuce is low in oxalate: about <1 mg per 1 cup shredded, which is 0% of the 50 mg a day many stone clinics aim for, or 0% of the 100 mg others allow.
50 or 100 mg a day: which target is yours
Why sources disagree on lettuce
The 3 studies here run from <1 to 14 mg per 1 cup shredded, measured between 2002 and 2023. They tested 3 preparations, and growing conditions, variety and lab method all move the number.
Where this number comes from
Each row is one published measurement, converted to a 36 g serving (1 cup shredded). 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 |
|---|---|---|---|
| 0 mg soluble only* | 0 mg | Raw (n=16) | Santamaria P., Elia A., Serio F., Todaro E, 1999via Foods 2023;12:3201, Table 5 (CC BY 4.0) |
| <1 mg | 0.3 mg | Raw (n=2) | Hönow R., Hesse A, 2002via Foods 2023;12:3201, Table 5 (CC BY 4.0) |
| <1 mg | 0.56 mg | Iceberg, raw | Harvard T.H, 2023 |
| <1 mg | 0.64 mg | Romaine, raw | Harvard T.H, 2023 |
| 14 mg | 40 mg | Raw | Kim D.-J., Kim H., Kim M., Lee J, 2007via 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