Avoid the Big Oxalates, Don't Sweat the Small Ones
Diet and Kidney Stones
Most of the foods that raise your kidney stone risk are foods you don't have to give up. You just need to know which ones matter most, and which ones you can stop worrying about.
General figures; individual results vary.
There are several types of kidney stones, but by far the most common is calcium oxalate. These form when there's too much oxalate in the urine, which binds to calcium and crystallizes over time. Unlike uric acid stones, which can sometimes be dissolved, calcium oxalate stones can't. If you've had one, prevention is the only strategy that works, and knowing which foods actually drive your oxalate up is one of the most effective things you can do.
The Oxalate List
Which high-oxalate foods actually matter
Oxalate shows up in a surprising number of foods, and some of the biggest offenders are otherwise the healthiest things you can eat. But "high in oxalate" gets applied to everything from beets to blueberries, and the gap between them is enormous. Beets carry roughly 75 times more oxalate than blueberries or celery, which get the same label.
The bottom line
Limit the top tier. Be sensible with the middle. Don't sweat the rest.
Highest Limit these
Beets, spinach, kale, okra, some nuts, dark chocolate, tea. These are the foods that move the needle.
Moderate Reasonable portions
Blueberries, celery, and other foods that get labeled "high" but sit nowhere near the worst offenders.
Lower Normal eating is fine
Bananas, apples, grapes, watermelon, potatoes, and most other vegetables.
Free download
The full High Oxalate List
Every food we've ranked, on one printable page for your fridge or your phone.
Download the listBackground reading: WebMD on kidney stone food causes.
Know Your Stones
How do I know what kind of stones I make?
Stone type matters for prevention, because not all stones form for the same reason. If you don't already know yours, ask your doctor. If they can't tell you, request a 24-hour urine test. It's the single best way to understand why you're forming stones, so your plan targets the right thing.
Nobody enjoys a urine collection, especially after something as painful as a stone. But between the inconvenience of the test and the pain of another stone, it isn't a close call.
Why Water Still Matters
Hydration first, but not hydration alone
Managing oxalate only helps if your kidneys can flush what you take in. Oxalate becomes a problem when it's concentrated in urine: the less diluted your urine, the more chances oxalate and calcium have to bond and crystallize. That's why doctors recommend more fluid for anyone with a stone history, whatever the stone type.
But water on its own is rarely enough. A large 2026 clinical trial, the PUSH trial published in The Lancet, randomized over 1,600 stone formers to intensive hydration coaching versus usual care. The hydration group produced meaningfully more urine, yet stone recurrence didn't drop significantly. The lesson isn't that hydration doesn't matter. It's that pairing it with something that changes your urine chemistry, like citrate, is what makes the difference. It also matters whether your body holds onto the water you drink, which is where balanced sodium and potassium come in.
Where KSPtabs Fits
Backup for the days you eat the spinach.
KSPtabs was developed by a board-certified urologist for exactly this problem. Add it to your water and the citrate gets to work binding calcium before oxalate can, leaving fewer opportunities for crystals to form. It also delivers balanced sodium and potassium so your body holds onto the water you drink, plus magnesium and vitamin B6 to help keep oxalate in check.
- ✓Drop one tablet in water, let it fizz, drink
- ✓Citrate + electrolytes to support healthy urinary citrate levels
- ✓33% increase in urinary citrate in a small clinical study*
*Median urinary citrate increased 33% during KSPtabs use. Small study in 10 healthy adults with no history of kidney stones; the study evaluated urine chemistry and did not assess kidney stone recurrence. Journal of Urology, 2021. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
Common Questions
Oxalate and kidney stone FAQ
Can I still eat spinach or kale if I've had a kidney stone?
In most cases, yes, in reasonable portions. Boiling cuts oxalate by roughly half, and pairing these foods with a calcium source like dairy at the same meal helps bind oxalate in the gut before it reaches your kidneys. KSPtabs adds another layer: its citrate binds calcium in your urine before oxalate can.
Do I need to avoid oxalates completely?
Almost never. Complete avoidance is only recommended for a small group of people with a specific diagnosis (hyperoxaluria) under a doctor's care. For most stone formers, the realistic strategy is limiting the highest-oxalate foods, staying hydrated, and giving your body extra backup like the citrate in KSPtabs.
Does eating calcium with oxalate-rich foods actually help?
Yes. Calcium and oxalate bind to each other in the digestive tract when eaten together, so less free oxalate gets absorbed and concentrated in urine. The key is the same meal; a calcium supplement at a different time of day doesn't do the same thing. KSPtabs works on the other end of that process, binding calcium in your urine to cover the oxalate that does get through.
How much water should I actually be drinking?
It varies by person, activity and climate, so this is a conversation for your doctor or urologist. A commonly cited target for stone formers is enough fluid to produce close to 2.5 liters of urine a day; pale yellow urine is usually a good sign. KSPtabs makes that habit do more work, since the sodium and potassium help you retain what you drink while you get the citrate benefit at the same time.
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This article is for general information and isn't a substitute for medical advice. Talk with your doctor about your specific kidney stone risk and diet.
