Asparagus is low in oxalates. Cooked asparagus contains roughly 5 to 17 mg of oxalate per 100 grams, depending on the source and preparation method. That places it well within the low-oxalate category used by kidney stone prevention guidelines, and it’s safe for most people watching their oxalate intake.
How Asparagus Compares to High-Oxalate Vegetables
The National Kidney Foundation lists asparagus as a “recommended” vegetable for people managing calcium oxalate kidney stones. It sits alongside broccoli, cucumber, green peas, lettuce, and lima beans in the low-to-medium oxalate group.
The vegetables flagged as high oxalate, and worth limiting if you’re stone-prone, are a different category entirely. Spinach, Swiss chard, kale, okra, collard greens, mustard greens, and parsley all carry the “avoid” label. Spinach and Swiss chard are rated “very high oxalate,” with spinach containing roughly 750 to 900 mg per 100 grams cooked. That’s 50 times or more the amount in the same weight of asparagus.
So if you’ve been avoiding asparagus because it’s a green vegetable and you assumed all greens are oxalate-heavy, there’s good news. The color of a vegetable tells you almost nothing about its oxalate load. Broccoli and lettuce are also low, while beets and rhubarb (neither of them green) rank among the highest.
Exact Oxalate Numbers for Asparagus
Oxalate measurements vary depending on the lab, the growing conditions, and how the asparagus is prepared. Wake Forest University School of Medicine’s oxalate food list puts cooked, boiled, and drained asparagus at 17.2 mg per 100 grams. The Oxalosis and Hyperoxaluria Foundation, which focuses specifically on oxalate-related conditions, reports a lower average of about 6 mg per 100 grams for boiled or steamed asparagus, with a half-cup serving (90 grams) coming in around 5 mg.
Either figure qualifies as low. NSW Health in Australia, which maintains clinical diet specifications, explicitly lists asparagus among vegetables containing less than 5 mg of oxalate per serving. A standard serving of four to six spears weighs roughly 60 to 90 grams, so even using the higher measurement, you’re looking at somewhere around 10 to 15 mg per serving.
What Counts as “Low Oxalate”
Most clinical guidelines define low-oxalate foods as those containing fewer than 10 mg per serving. Medium-oxalate foods fall between 10 and 25 mg per serving. High-oxalate foods exceed 25 mg, and some, like spinach or rhubarb, can deliver hundreds of milligrams in a single portion.
A typical low-oxalate diet aims to keep total daily oxalate intake between 40 and 50 mg per day, though individual targets vary based on your stone history and what your doctor recommends. At 5 to 15 mg per serving, asparagus fits comfortably into that budget without taking up a large share. You could eat a generous portion alongside other low-oxalate foods and stay well within range.
Why Preparation Matters
Boiling asparagus in water tends to reduce its oxalate content because some oxalate is water-soluble and leaches into the cooking liquid. This partly explains the range in reported values. Steaming retains slightly more oxalate than boiling, but the difference is small for a vegetable that starts low to begin with. Raw asparagus has not been as extensively tested, though its oxalate content is generally similar to or slightly higher than the cooked form.
If you’re actively managing kidney stones and want to minimize oxalate from every source, boiling and discarding the water is the most effective cooking method across all vegetables. For asparagus specifically, though, the reduction is modest because there isn’t much oxalate to remove in the first place.
Calcium, Potassium, and Oxalate Absorption
One cup of cooked asparagus provides about 21 mg of calcium and 202 mg of potassium. The calcium content is relevant because calcium binds to oxalate in your digestive tract, forming a compound your body can’t absorb. This means the oxalate passes through you rather than being filtered by your kidneys, where it could contribute to stone formation.
Eating calcium-rich foods alongside oxalate-containing foods is one of the most effective dietary strategies for reducing oxalate absorption. Asparagus doesn’t deliver a large amount of calcium on its own, but pairing it with dairy, fortified foods, or other calcium sources at the same meal further neutralizes whatever small amount of oxalate it contains. This is why kidney stone guidelines no longer recommend cutting calcium. Instead, they recommend eating calcium and oxalate together so the two bind before reaching your kidneys.
Potassium plays a different role. Adequate potassium intake helps maintain the chemical balance of your urine and may reduce calcium excretion, which lowers the raw material available for stone formation. At 202 mg per cup, asparagus contributes meaningfully to your daily potassium needs.
Who Needs to Think About Oxalates
Most people don’t need to track oxalate intake at all. Low-oxalate diets are primarily recommended for people who have had calcium oxalate kidney stones (the most common type, accounting for about 80% of all kidney stones) or who have been diagnosed with hyperoxaluria, a condition where oxalate levels in the urine are abnormally high.
If you fall into one of those groups, asparagus is one of the safer vegetable choices available. It delivers fiber, folate, and vitamins A, C, and K without meaningfully raising your oxalate load. The vegetables to watch carefully are the ones on the “very high” list: spinach, Swiss chard, beet greens, and rhubarb. A single half-cup serving of cooked spinach can deliver more oxalate than you’d get from eating asparagus every day for a week.