The single most repeated stone tip is "avoid spinach," and it is not wrong — but it misses the part that makes the advice livable. Oxalate is water-soluble, which means cooking method changes how much of it survives the trip from pan to plate. The vegetable is not the enemy; the preparation is the lever.
Oxalate dissolves in water. When you boil leafy greens and then discard the cooking water, a substantial fraction of the oxalate goes out with that water rather than staying in the plant. Steaming helps less because the oxalate has nowhere to go; boiling with drainage helps more. This is a physical fact about the molecule, not a diet fad, and it is why the same spinach that is a problem raw becomes a smaller problem when boiled and drained.
The trade is not "eat unlimited boiled spinach." It is "you do not have to exile an entire vegetable group." A measured plate keeps the highest-oxalate greens portioned and cooked, leans on the low-oxalate produce, and pairs the meal with calcium so whatever oxalate remains binds in the gut.
The spread is wide, and cooking moves several of these down a tier:
| Food | Oxalate (mg) | Serving | Rating |
|---|---|---|---|
| Spinach, raw | 590 mg | 1 serving | Avoid |
| Rhubarb, raw | 1,293 mg | 1 cup diced | Avoid |
| Beets, boiled or pickled | 48 mg | 1/2 cup | Caution |
| Dark chocolate | 65 mg | 1 oz | Caution |
| Kale, cooked | 3 mg | 1/2 cup | Safe |
| Broccoli, raw | 6 mg | 1 cup sliced | Safe |
Spinach and rhubarb are the two to respect — boil and portion, or simply eat rarely. Kale cooked and broccoli raw sit safe, which is why a stone-friendly plate can still be green without being a spinach-only affair. Beets and dark chocolate are the moderate middle: fine in small amounts, not daily staples.
Three habits cover most of the upside. Boil high-oxalate greens and pour the water off rather than using it in soup. Rotate in the low-oxalate vegetables — kale, broccoli, cabbage, cauliflower — so the plate stays varied. And keep a calcium source with the meal, because the remaining oxalate is exactly what dietary calcium is built to catch in the gut. None of this requires giving up vegetables; it requires cooking the right ones the right way.
See how oxalate values are measured and verified on our data methodology page.