Low Oxalate Foods List for Kidney Stone Prevention

Short answer: A low-oxalate diet is not for the general public. It is a targeted therapeutic approach for people who form calcium oxalate kidney stones, which account for roughly 75% to 80% of all kidney stones⁽¹⁾. If you have never had a stone and your urologist has not tested your 24-hour urine, cutting spinach out of your smoothies is not a health strategy. If you have had calcium oxalate stones, the evidence-based approach is not simply “eat less oxalate.” It combines moderate oxalate restriction with adequate dietary calcium at meals, high fluid intake, controlled sodium and animal protein, and testing to see what is actually driving your stones⁽¹⁾⁽²⁾.

This article explains what oxalate is, who benefits from limiting it, a low-oxalate foods list with practical portion guidance, the foods to eat sparingly, and why calcium at meals is often more important than avoiding oxalate entirely.

What oxalate actually is

Oxalate (or oxalic acid) is a small organic molecule found naturally in many plant foods and produced in small amounts by the liver from vitamin C and other precursors. In the gut, oxalate binds to calcium and iron. If enough calcium is available in the same meal, the oxalate-calcium complex passes out in the stool and never enters the bloodstream. If calcium is low or oxalate is very high, more free oxalate is absorbed, filtered by the kidneys, and excreted in urine, where it can combine with urinary calcium to form calcium oxalate crystals. Over time and with the right combination of factors (concentrated urine, high sodium, low citrate, low urine volume), those crystals can aggregate into a stone.

Oxalate content in foods is typically reported in mg per 100 g or per standard serving. Categories commonly used by clinical dietitians:

• Very low: under 2 mg per serving.
• Low: 2 to 10 mg per serving.
• Moderate: 10 to 40 mg per serving.
• High: 40 mg or more per serving.

The commonly used clinical target is roughly 40 to 50 mg of oxalate per day for people with hyperoxaluria (high urinary oxalate) documented on a 24-hour urine test.

Who actually needs a low-oxalate diet

A low-oxalate diet is generally recommended for:

• People who have formed calcium oxalate kidney stones and have documented hyperoxaluria on 24-hour urine testing.
• People with enteric hyperoxaluria (fat malabsorption from short bowel syndrome, Crohn disease, gastric bypass, chronic pancreatitis, or cystic fibrosis), where unabsorbed fat binds calcium in the gut and leaves more oxalate free to be absorbed.
• People with primary hyperoxaluria (a rare genetic disorder of oxalate metabolism), under specialist care.

Most people with kidney stones do not need aggressive oxalate restriction. Uric acid stones, calcium phosphate stones, struvite stones, and cystine stones each have different dietary priorities. And even for calcium oxalate stones, calcium intake, fluid intake, sodium, animal protein, and citrate often matter more than dietary oxalate alone⁽¹⁾.

A myth worth killing: calcium is not the enemy

For decades, kidney-stone patients were told to avoid dairy. That advice was wrong for most people and is now considered harmful. Dietary calcium eaten at the same meal as oxalate-containing foods binds oxalate in the gut so it is excreted in stool rather than absorbed. Restricting dietary calcium actually increases urinary oxalate and stone risk. Randomized and cohort evidence supports adequate (not high) dietary calcium, roughly 1,000 to 1,200 mg per day from food, spread across meals, as part of stone prevention in calcium oxalate stone formers⁽¹⁾. Calcium supplements are a different issue: taken away from meals, they can raise urinary calcium without the benefit of binding gut oxalate; ask your clinician before starting supplements.

Low-oxalate foods list (safe to enjoy)

These foods contain very low to low oxalate (roughly under 10 mg per typical serving) and can generally be eaten freely in a stone-prevention diet.

Vegetables

• Cauliflower
• Cabbage (green, red, savoy)
• Bok choy
• Iceberg and butterhead lettuce
• Cucumber (peeled)
• Zucchini and yellow summer squash
• Mushrooms (most varieties)
• Onions and shallots
• Peas (green, fresh or frozen, in modest portions)
• Radish
• Bell peppers (red, yellow, green)
• Broccoli (small portions; moderate at large portions)
• Kale (baby kale, in modest portions; larger portions climb into moderate)

Fruits

• Apples (peeled or with peel; low)
• Bananas
• Blueberries
• Cherries
• Grapes
• Melons (watermelon, cantaloupe, honeydew)
• Peaches, nectarines
• Pears (peeled)
• Pineapple
• Plums
• Mango
• Strawberries (in modest portions)

Grains and starches

• White rice
• Egg noodles and pasta made from refined semolina
• Sourdough or white bread (moderate portions)
• Corn tortillas (in modest portions)
• Oats (small servings; larger servings climb into moderate)
• Potato (peeled, boiled) in modest portions

Proteins

• Eggs
• Chicken and turkey
• Fish and shellfish
• Lean pork and beef (in moderation for other reasons; see animal protein note below)
• Low-fat plain yogurt, milk, cottage cheese (at meals for the calcium-oxalate binding effect)
• Hard cheeses (cheddar, mozzarella, feta, parmesan)

Fats and beverages

• Olive oil, avocado oil, butter
• Water (the single most important stone-prevention beverage)
• Lemonade and lemon water (citrate is protective)
• Herbal teas (not black tea, which is high oxalate)
• Coffee in moderation (2 to 3 cups per day is compatible with stone prevention in most people)

Moderate-oxalate foods (portion control)

These foods are not banned but should be eaten in modest portions and, importantly, paired with a calcium source at the same meal.

• Sweet potato (a medium sweet potato is moderate to high)
• Regular potato with skin
• Carrot
• Broccoli in large portions
• Green beans
• Tomato and tomato products
• Celery
• Whole-wheat bread and pasta
• Brown rice
• Corn
• Oranges, tangerines, kiwi
• Raspberries, blackberries
• Dates and figs
• Peanut butter (small servings only; large servings are high)
• Sesame seeds (small sprinkling only)

High-oxalate foods (limit or avoid if hyperoxaluric)

These contain 40 mg or more of oxalate per typical serving. If you have documented calcium oxalate stones and hyperoxaluria, treat these as occasional foods and always pair with a calcium source.

• Spinach (extremely high, a single half-cup of cooked spinach can exceed 500 mg)
• Swiss chard
• Beet greens and beets (especially raw)
• Rhubarb
• Amaranth leaves
• Sorrel and purslane
• Almonds and almond flour
• Cashews
• Peanuts and peanut flour (large servings)
• Sesame seeds in large amounts (tahini)
• Buckwheat (kasha) and buckwheat flour
• Quinoa (moderate to high depending on serving)
• Wheat bran and bran cereals
• Miso and heavy soy products in large amounts
• Black tea (large amounts)
• Dark chocolate and cocoa powder
• Star fruit (also directly nephrotoxic and to be avoided entirely in kidney disease)

The five habits that matter as much as (or more than) oxalate

1. Drink enough water to make 2 to 2.5 L of urine per day

For most adults that means about 2.5 to 3 L of fluid intake per day, more in hot climates or with sweating. Dilute urine dramatically reduces the chance of crystal aggregation.

2. Get 1,000 to 1,200 mg of dietary calcium daily, with meals

Milk, yogurt, cheese, calcium-fortified plant milks, and canned fish with bones (sardines, salmon) all count. Spread it across meals, especially any meal containing higher-oxalate foods.

3. Keep sodium under about 2,300 mg per day

High sodium raises urinary calcium and increases stone risk. Read labels: bread, cheese, soups, sauces, and restaurant food are the usual culprits, not the shaker on the table.

4. Moderate animal protein

Very high intakes of meat, poultry, and fish raise urinary uric acid and calcium and lower urinary citrate, all of which favor stone formation. Aim for palm-sized portions at meals rather than large-portion animal-protein plates.

5. Include citrate

Lemonade, lemon water, and orange juice provide dietary citrate, which binds urinary calcium and inhibits crystal formation. Your urologist may also prescribe potassium citrate if 24-hour urine testing shows low urinary citrate.

Cooking tips that lower oxalate exposure

• Boiling vegetables and discarding the water reduces oxalate content by roughly 30% to 90% depending on the vegetable, because oxalate is water soluble. Steaming reduces less.
• Soaking legumes overnight and discarding the soaking water removes some oxalate.
• Pair high-oxalate foods with dairy at the same meal (yogurt with berries, cheese with whole-grain toast).
• Peeling potatoes and sweet potatoes removes some oxalate concentrated in the skin.
• Do not take vitamin C supplements above about 500 mg per day if you are a calcium oxalate stone former; the body converts excess ascorbate to oxalate.

What a low-oxalate day can look like

• Breakfast: Plain Greek yogurt with sliced peach and a sprinkle of low-oxalate oats. Coffee with milk. Water.
• Lunch: Turkey and cheddar sandwich on sourdough with lettuce, cucumber, and a light mayo; carrot sticks; a pear; water.
• Snack: Cottage cheese with blueberries; sparkling water with lemon.
• Dinner: Baked salmon, white rice, roasted zucchini and yellow squash, side salad of iceberg or butter lettuce with olive oil and lemon. Water.
• Dessert: Bowl of melon or grapes.
• Throughout the day: steady water intake; a glass of unsweetened lemonade with lunch or dinner for citrate.

When to ask for testing rather than restricting

If you have had one or more kidney stones, the American Urological Association recommends 24-hour urine testing (usually two collections) to identify the specific metabolic drivers of your stones (oxalate, calcium, uric acid, citrate, sodium, volume, pH)⁽²⁾. Diet advice is much more effective when it targets your actual numbers. Ask your urologist about:

• Stone composition analysis if you passed a stone.
• 24-hour urine study on your usual diet.
• Referral to a registered dietitian who specializes in nephrology or urology nutrition.

Frequently asked questions

Should everyone follow a low-oxalate diet?

No. A low-oxalate diet is intended for people who form calcium oxalate kidney stones and have documented high urinary oxalate, or for people with enteric hyperoxaluria or primary hyperoxaluria. For the general population there is no evidence that avoiding oxalate improves health.

Is spinach really that bad?

Spinach is the highest-oxalate common food (often 500 mg or more per cooked half-cup). If you have hyperoxaluric calcium oxalate stones, spinach should be occasional at most, and always with a calcium source. If you have never had a stone, spinach is a nutritious food and does not need to be avoided.

Do I have to give up nuts?

Almonds and cashews are high oxalate; peanuts are moderate to high depending on portion. Walnuts, pistachios, and pecans are lower. Small portions of any nut with a calcium-containing meal are generally tolerated.

Can I still drink coffee?

Yes for most people. Two to three cups of coffee per day is compatible with kidney-stone prevention and may even reduce stone risk in cohort studies. Black tea is higher in oxalate and should be limited if you are a calcium oxalate stone former.

Why can’t I just take a calcium supplement?

Calcium supplements taken away from meals can raise urinary calcium without providing the gut-oxalate-binding benefit of dietary calcium eaten with food. If a supplement is needed, take it with meals and discuss dose with your clinician.

Is a low-oxalate diet the same as a low-purine or low-sodium diet?

No. Low-oxalate targets calcium oxalate stones. Low-purine targets uric acid stones and gout. Low-sodium is generally beneficial for stone prevention (reduces urinary calcium) and blood pressure, but it is separate from oxalate restriction. Your 24-hour urine and stone composition guide which diet fits you.

Are megadoses of vitamin C safe if I form kidney stones?

No. Vitamin C in doses above about 500 mg per day is converted in the body to oxalate and can raise urinary oxalate. Stick to food sources and standard multivitamin doses unless a clinician has directed otherwise.

Medical disclaimer: This article is for informational purposes only and is not a substitute for medical advice, diagnosis, or treatment. A low-oxalate diet is a therapeutic diet for specific medical conditions and is not recommended for the general public. If you have had kidney stones, discuss stone composition analysis, 24-hour urine testing, and dietary strategy with a urologist and a registered dietitian who specializes in kidney nutrition. Do not begin a restrictive diet without clinical guidance, particularly if you have chronic kidney disease, diabetes, gastrointestinal disease, are pregnant, or take medications that affect kidney function. Not medical advice; consult a registered dietitian before making major dietary changes.