Oxalate in Foods: Low-Oxalate Diet Guide for Kidney Stone Prevention

Q: What are oxalates and why do they cause kidney stones?

Oxalates (oxalic acid) are naturally occurring compounds found in many plant foods. When oxalate binds with calcium in the kidneys, it forms calcium oxalate crystals — the most common type of kidney stone (about 80% of all cases). Reducing dietary oxalate can help prevent recurrence.

Q: How much oxalate per day is safe for kidney stone prevention?

Most urologists and dietitians recommend keeping dietary oxalate below 40–50 mg per day for people prone to calcium oxalate kidney stones. Some stricter protocols recommend <40 mg/day. Always consult your doctor for personalised guidance.

Q: Which foods are highest in oxalates?

The highest-oxalate foods include spinach (1,000+ mg per cup cooked), rhubarb, beets, swiss chard, almonds, dark chocolate, sweet potatoes, and navy beans. Dried figs, buckwheat flour, and some seaweed (dulse, nori) are also very high. Check our database above for the complete list.

Q: Does cooking reduce oxalate in food?

Yes. Boiling is the most effective method and can reduce soluble oxalate by 30–87% depending on the food, because oxalate leaches into the cooking water (which should be discarded). Steaming and baking are less effective but still help. Soaking beans and grains before cooking also reduces oxalate content.

Q: How can I reduce calcium oxalate kidney stone formation?

Key strategies include: (1) staying well hydrated (2.5–3 L of water/day), (2) following a low-oxalate diet (<40–50 mg/day), (3) eating calcium-rich foods (dairy, fortified plant milks) at the same meal as higher-oxalate foods so calcium binds oxalate in the gut, (4) boiling high-oxalate vegetables to leach oxalate into the water, and (5) limiting sodium and animal protein which can increase urinary calcium. Do not restrict calcium — low-calcium diets actually increase stone risk.

Q: What is a low-oxalate diet?

A low-oxalate diet limits oxalate intake to under 40–50 mg per day. It focuses on choosing foods with <5 mg oxalate per serving (like white rice, eggs, dairy, most meats, cauliflower, cabbage) and avoiding very high sources (spinach, rhubarb, almonds, beets). It's important to stay well hydrated and include adequate calcium.

Search, filter, and compare the oxalate content of 250+ foods compiled from 4 independent, peer-reviewed scientific sources. Serving sizes are standardised (1 cup, 100g, 1 fruit) for direct comparison. Use this tool to plan a low-oxalate diet for kidney stone prevention.

266 results

		Serving
Spinach, boiled (total oxalate)	Vegetables	100g	2350	Very High	PMC Review
Licorice root (total oxalate)	Ingredients	100g	2162	Very High	PMC Review
Amaranth, raw (total oxalate)	Vegetables	100g	1510.8	Very High	PMC Review
Spinach, cooked	Vegetables	1 cup	1510	Very High	UChicago
Parsley, raw (total oxalate)	Vegetables	100g	1338.3	Very High	PMC Review
Rhubarb (total oxalate)	Vegetables	100g	1235	Very High	PMC Review
Spinach, boiled	Vegetables	1 cup	1094.8	Very High	Harvard*
Rhubarb	Vegetables	1 cup	1082	Very High	UChicago
Sorrel (soluble oxalate)	Vegetables	100g	1079	Very High	PMC Review
Star fruit (total oxalate)	Fruits	100g	953	Very High	PMC Review
Swiss chard (total oxalate)	Vegetables	100g	874	Very High	PMC Review
Taro leaves, raw (total oxalate)	Vegetables	100g	721.9	Very High	PMC Review
Cocoa (total oxalate)	Beverages	100g	700	Very High	PMC Review
Spinach, raw	Vegetables	1 cup	656	Very High	UChicago
Taro leaves, raw	Vegetables	100g	652	Very High	OHF
Flour, almond meal	Flours & Starches	100g	519	Very High	OHF
Almonds	Nuts & Seeds	100g	430.3	Very High	UChicago
Spinach, raw (total oxalate)	Vegetables	100g	329.6	Very High	PMC Review
Spinach, raw	Vegetables	1 cup	316.2	Very High	Harvard*
Rice bran	Grains & Pasta	1 cup	281	Very High	UChicago
Flour, buckwheat	Flours & Starches	100g	280	Very High	OHF
Almonds, oil roasted	Nuts & Seeds	100g	254	Very High	Harvard*
Cashews, oil roasted	Nuts & Seeds	100g	224	Very High	Harvard*
Navy beans, canned	Beans & Lentils	1 cup	192.6	Very High	Harvard*
Cashews	Nuts & Seeds	100g	172.8	Very High	UChicago
Mixed nuts with peanuts	Nuts & Seeds	100g	159.4	Very High	Harvard
Chocolate, dark bar	Candy & Chocolate	100g	159.2	Very High	Harvard*
Hummus, commercial	Beans & Lentils	1 cup	156.4	Very High	Harvard
Beets, canned	Vegetables	1 cup	152.8	Very High	Harvard*
Beets	Vegetables	1 cup	152	Very High	UChicago
Navy beans	Beans & Lentils	1 cup	152	Very High	UChicago
Soybean (total oxalate)	Beans & Lentils	100g	142	Very High	PMC Review
Seaweed, Dulse flakes	Vegetables	100g	136	Very High	OHF
Flour, soy	Flours & Starches	100g	135	Very High	OHF
Buckwheat groats, cooked	Grains & Pasta	1 cup	133	Very High	UChicago
Buckwheat groats, cooked	Grains & Pasta	1 cup	132.6	Very High	Harvard*
Refried beans, canned	Beans & Lentils	1 cup	119.2	Very High	Harvard
Baked beans, canned	Beans & Lentils	1 cup	115	Very High	Harvard
Okra	Vegetables	1 cup	114	Very High	UChicago
Miso soup	Soups	1 cup	111	Very High	UChicago
Sweet potato, baked	Vegetables	1 cup	108.4	Very High	Harvard*
Peanuts, oil roasted	Nuts & Seeds	100g	102.3	Very High	Harvard*
Tomato paste, canned	Vegetables	1 cup	98	Very High	Harvard
Wheat berries, cooked	Grains & Pasta	1 cup	97.6	Very High	Harvard
Baked potato with skin	Vegetables	1 medium	97	Very High	UChicago
Corn grits, cooked	Hot Cereal	1 cup	97	Very High	UChicago
Seaweed, Nori, dry roasted	Vegetables	100g	97	Very High	OHF
Soybeans, green, boiled	Vegetables	1 cup	96	Very High	Harvard
Peanuts	Nuts & Seeds	100g	95.2	Very High	UChicago
Soy flour	Ingredients	1 cup	94	Very High	UChicago
Potato, baked with skin	Vegetables	1 medium	91.7	Very High	Harvard*
Starch, arrowroot	Flours & Starches	100g	89	Very High	OHF
Bitter gourd (bitter melon), wok-fried	Vegetables	100g	88	Very High	OHF
Bulgur, cooked	Grains & Pasta	1 cup	86	Very High	UChicago
Bitter gourd (bitter melon), raw	Vegetables	100g	86	Very High	OHF
Bulgur, cooked	Grains & Pasta	1 cup	85.9	Very High	Harvard*
Yams	Vegetables	1 cup	80	Very High	UChicago
Beetroot, boiled (total oxalate)	Vegetables	100g	76	Very High	PMC Review
Mushrooms, variety, dried	Vegetables	100g	76	Very High	OHF
Plums (prunes), dried	Fruits	1 cup	71.2	Very High	Harvard*
Potato chips, baked	Snacks	100g	68.1	Very High	Harvard*
Potato, microwaved	Vegetables	1 medium	68	Very High	Harvard*
Beetroot, raw (total oxalate)	Vegetables	100g	67	Very High	PMC Review
Hot chocolate, homemade	Beverages	1 cup	65	Very High	UChicago
Candy bar (e.g. Snickers)	Candy & Chocolate	100g	62.4	Very High	Harvard*
Rutabaga, mashed	Vegetables	1 cup	62	Very High	UChicago
Millet, cooked	Grains & Pasta	1 cup	62	Very High	UChicago
Flour, cassava	Flours & Starches	100g	61	Very High	OHF
Turnip, mashed	Vegetables	1 cup	60	Very High	UChicago
Miso soup	Soups	1 cup	58.3	Very High	Harvard
Plant-based burger patty	Beans & Lentils	1 patty	57.9	Very High	Harvard*
Pecans, oil roasted	Nuts & Seeds	100g	55.4	Very High	Harvard*
Quinoa, cooked	Grains & Pasta	1 cup	54.4	Very High	Harvard
Potato salad	Vegetables	1 cup	50.7	Very High	Harvard*
Cocoa powder	Ingredients	1 tbsp	50.3	Very High	UChicago
Miso paste, red	Condiments	100g	49	Very High	OHF
Raspberries	Fruits	1 cup	48	Very High	UChicago
Tempeh	Beans & Lentils	100g	48	Very High	OHF
Spaghetti, whole wheat, cooked	Grains & Pasta	1 cup	46.1	Very High	Harvard
Raisin Bran cereal	Cold Cereal	1 cup	46.1	Very High	Harvard*
Meat lasagna	Mixed Dishes	1 piece/cup	45.7	Very High	Harvard
Corn grits, cooked	Hot Cereal	1 cup	45.2	Very High	Harvard
Potato chips, regular	Snacks	100g	42.7	Very High	Harvard*
40% Bran Flakes cereal	Cold Cereal	1 cup	42.7	Very High	Harvard*
Almond butter	Nuts & Seeds	1 tbsp	41.6	Very High	Harvard
Walnuts	Nuts & Seeds	100g	41.3	Very High	Harvard*
Lentil soup	Soups	1 cup	39	Very High	UChicago
Carrot, raw (total oxalate)	Vegetables	100g	37.7	Very High	PMC Review
Blueberries	Fruits	1 cup	37	Very High	Harvard*
Stuffing	Mixed Dishes	1 cup	36	Very High	UChicago
Brussels sprouts, boiled	Vegetables	1 cup	34	Very High	Harvard
Tomato sauce	Vegetables	1 cup	34	Very High	UChicago
Brownie, ready-to-eat	Breads & Bakery	1 brownie	33.9	Very High	Harvard*
Lentil soup	Soups	1 cup	33.6	Very High	Harvard
Flour, tapioca	Flours & Starches	100g	33	Very High	OHF
Frosted Mini-Wheats cereal	Cold Cereal	25 biscuits	32.9	Very High	Harvard*
Pistachios, dry roasted	Nuts & Seeds	100g	31.7	Very High	Harvard*
Shredded Wheat cereal	Cold Cereal	1 cup	31.4	Very High	Harvard*
Parsnip	Vegetables	1 cup	30	Very High	UChicago
Edamame	Beans & Lentils	100g	30	Very High	OHF
Orange	Fruits	1 fruit	29	Very High	UChicago
French fries, fast food	Vegetables	100g	28.6	Very High	Harvard*
Sweet potato, canned	Vegetables	1 cup	28.6	Very High	Harvard*
Juice, carrot	Beverages	1 cup	28.3	Very High	Harvard
English muffin, whole wheat	Breads & Bakery	1 muffin	28.1	Very High	Harvard
Green beans, boiled	Vegetables	1 cup	27.2	Very High	Harvard*
Almond milk	Beverages	1 cup	27.1	Very High	Harvard
Carrot juice	Beverages	1 cup	27	Very High	UChicago
Walnuts	Nuts & Seeds	100g	26.5	Very High	UChicago
Grapefruit	Fruits	1 fruit	26.4	Very High	Harvard*
Tortilla corn chips	Snacks	100g	25	Very High	Harvard*
Flour, rice (white/brown)	Flours & Starches	100g	25	Very High	OHF
Dates	Fruits	1 date	24	Very High	UChicago
Brown rice, cooked	Grains & Pasta	1 cup	24	Very High	UChicago
Chili with beans	Mixed Dishes	1 cup	24	Very High	UChicago
Pineapple, canned	Fruits	1 cup	23.8	Very High	Harvard*
Orange	Fruits	1 fruit	23.3	Very High	Harvard*
French fries, sweet potato	Vegetables	100g	21.8	Very High	Harvard
French fries, frozen prepared	Vegetables	100g	21.7	Very High	Harvard
Black beans, boiled	Beans & Lentils	1 cup	21	Very High	Harvard*
Marinara / spaghetti sauce	Vegetables	1 cup	20.8	Very High	Harvard*
Red kidney beans, boiled	Beans & Lentils	1 cup	19.8	Very High	Harvard*
Peanut butter	Nuts & Seeds	1 tbsp	19.2	Very High	Harvard*
Avocado	Fruits	1 fruit	19	Very High	Harvard*
Avocado	Fruits	1 fruit	19	Very High	UChicago
Chocolate syrup	Candy & Chocolate	1 tbsp	19	Very High	UChicago
Brown rice, cooked	Grains & Pasta	1 cup	18.7	Very High	Harvard*
Bread, multigrain	Breads & Bakery	1 slice	18	Very High	Harvard
V8 vegetable juice	Beverages	1 cup	18	Very High	UChicago
Cream of Wheat, cooked	Hot Cereal	1 cup	17.7	Very High	Harvard*
Asparagus, boiled	Vegetables	1 cup	17.4	Very High	Harvard
Spaghetti, cooked	Grains & Pasta	1 cup	16.5	Very High	Harvard*
Milk chocolate	Candy & Chocolate	100g	16.5	Very High	Harvard*
Carrots, boiled	Vegetables	1 cup	16.4	Very High	Harvard*
Tahini (sesame butter)	Nuts & Seeds	1 tbsp	16.2	Very High	Harvard
Pretzels, hard salted	Snacks	100g	16.2	Very High	Harvard*
Broccoli, raw (total oxalate)	Vegetables	100g	16.1	Very High	PMC Review
Kiwi	Fruits	1 fruit	16	Very High	Harvard
Kiwi	Fruits	1 fruit	16	Very High	UChicago
Tahini	Nuts & Seeds	1 tbsp	16	Very High	UChicago
Farina cereal, cooked	Hot Cereal	1 cup	16	Very High	UChicago
Tangerine	Fruits	1 fruit	15.7	Very High	Harvard
Macaroni and cheese	Mixed Dishes	1 cup	15.3	Very High	Harvard
Couscous, cooked	Grains & Pasta	1 cup	15.1	Very High	Harvard*
Crackers, whole wheat	Breads & Bakery	5-6 crackers	15	Very High	Harvard*
Lemonade, from concentrate	Beverages	1 cup	14.9	Very High	Harvard*
Juice, tomato, canned	Beverages	1 cup	14.3	Very High	Harvard*
Tea, brewed	Beverages	1 cup	14	Very High	UChicago
Bread, whole wheat	Breads & Bakery	1 slice	13.6	Very High	Harvard*
Clam chowder	Soups	1 cup	13.6	Very High	Harvard*
Peanut butter	Nuts & Seeds	1 tbsp	13	Very High	UChicago
Bamboo shoots, canned	Vegetables	1 cup	12.6	Very High	Harvard
Broccoli, boiled	Vegetables	1 cup	12	Very High	Harvard
Soy burger	Beans & Lentils	100g	12	Very High	Harvard*
Potato, mashed	Vegetables	1 cup	11.6	High	Harvard*
Spaghetti, cooked	Grains & Pasta	1 cup	11	High	UChicago
Tofu, soft	Beans & Lentils	100g	10.7	High	Harvard*
Pineapple, raw	Fruits	1 cup	10.4	High	Harvard
Banana	Fruits	1 fruit	10.3	High	Harvard*
Broccoli, boiled (total oxalate)	Vegetables	100g	10.1	High	PMC Review
Chickpeas (garbanzo), boiled/canned	Beans & Lentils	100g	10	High	OHF
Flour, chickpea	Flours & Starches	100g	10	High	OHF
Collards, boiled	Vegetables	1 cup	9.8	Moderate	Harvard
Soy milk, fortified	Beverages	1 cup	9.6	Moderate	Harvard
Fig, raw	Fruits	1 fig	9.3	Moderate	Harvard*
Flour, coconut	Flours & Starches	100g	9	Moderate	OHF
Pumpkin, canned	Vegetables	1 cup	8.8	Moderate	Harvard
Raisins	Fruits	100g	8.8	Moderate	Harvard*
Sunflower seeds, dried	Nuts & Seeds	100g	8.3	Moderate	Harvard*
Winter squash, baked	Vegetables	1 cup	8	Moderate	Harvard*
Bok choy, leaves	Vegetables	100g	8	Moderate	OHF
Tofu (soybean curd)	Beans & Lentils	100g	8	Moderate	OHF
Celery, raw	Vegetables	1 stalk	7.6	Moderate	Harvard
Banana (total oxalate)	Fruits	100g	6.8	Moderate	PMC Review
Tea, brewed black	Beverages	1 cup	6.4	Moderate	Harvard*
Tea, green unsweetened	Beverages	1 cup	6.4	Moderate	Harvard
Bread, rye	Breads & Bakery	1 slice	6.3	Moderate	Harvard*
Black tea infusion (soluble oxalate)	Beverages	100ml	6.1	Moderate	PMC Review
Cantaloupe	Fruits	1 fruit	5.6	Moderate	Harvard*
Dates	Fruits	1 date	5.1	Moderate	Harvard
Raspberries	Fruits	1 cup	5	Moderate	Harvard*
Figs, dried	Fruits	1 fig	5	Moderate	Harvard
Tortillas, corn	Breads & Bakery	1 tortilla	5	Moderate	Harvard*
Seaweed, Kombu	Vegetables	100g	5	Moderate	OHF
Cheerios cereal	Cold Cereal	1 cup	4.9	Low	Harvard*
Lentils, boiled	Beans & Lentils	1 cup	4.8	Low	Harvard*
Dried figs	Fruits	1 piece	4.8	Low	UChicago
Carrots, raw	Vegetables	1/2 large	4.5	Low	Harvard*
Tortillas, flour	Breads & Bakery	1 tortilla	4.5	Low	Harvard*
Bread, white	Breads & Bakery	1 slice	4.4	Low	Harvard*
Pizza, cheese	Mixed Dishes	1 slice	4.3	Low	Harvard*
White rice, cooked	Grains & Pasta	1 cup	4	Low	UChicago
Blueberries	Fruits	1 cup	4	Low	UChicago
Strawberries	Fruits	1 cup	4	Low	UChicago
White rice, cooked	Grains & Pasta	1 cup	3.8	Low	Harvard*
Apple, raw (total oxalate)	Fruits	100g	3.5	Low	PMC Review
Cherries, sweet	Fruits	1 cup	3.4	Low	Harvard
Banana	Fruits	1 fruit	3	Low	UChicago
Starch, potato	Flours & Starches	100g	3	Low	OHF
Starch, corn (cornstarch)	Flours & Starches	100g	3	Low	OHF
Soy sauce	Condiments	1 tbsp	2.9	Very Low	Harvard*
Cabbage, boiled	Vegetables	1 cup	2.8	Very Low	Harvard*
Green tea infusion (soluble oxalate)	Beverages	100ml	2.7	Very Low	PMC Review
Beer	Beverages	1 cup	2.6	Very Low	Harvard*
Strawberries	Fruits	1 cup	2.4	Very Low	Harvard*
Grapes, seedless	Fruits	1 cup	2.4	Very Low	Harvard*
Kale, boiled	Vegetables	1 cup	2.2	Very Low	Harvard*
Onion, raw	Vegetables	1 onion	2.1	Very Low	Harvard*
Rice Krispies cereal	Cold Cereal	1 cup	2.1	Very Low	Harvard*
Broccoli	Vegetables	1 cup	2	Very Low	UChicago
Kale	Vegetables	1 cup	2	Very Low	UChicago
Cabbage	Vegetables	1 cup	2	Very Low	UChicago
Cauliflower, cooked	Vegetables	1 cup	2	Very Low	UChicago
Seaweed, Wakame	Vegetables	100g	2	Very Low	OHF
Bok choy, stalks, diced	Vegetables	100g	2	Very Low	OHF
Water chestnuts, canned	Vegetables	100g	2	Very Low	OHF
Wine, red	Beverages	1 cup	1.9	Very Low	Harvard*
Pear	Fruits	1 fruit	1.8	Very Low	Harvard*
Olives, canned ripe	Fruits	1 olive	1.7	Very Low	Harvard*
Coffee, brewed	Beverages	1 cup	1.7	Very Low	Harvard*
Tomato, ripe red	Vegetables	1 slice	1.6	Very Low	Harvard*
Corn kernels, boiled	Vegetables	1 cup	1.6	Very Low	Harvard*
Popcorn, microwave	Snacks	1 cup	1.6	Very Low	Harvard*
Juice, orange	Beverages	1 cup	1.5	Very Low	Harvard*
Tuna, light canned in water	Fish	100g	1.5	Very Low	Harvard*
Ketchup	Condiments	1 tbsp	1.5	Very Low	Harvard*
Squash, summer, boiled	Vegetables	1 cup	1.2	Very Low	Harvard*
Peppers, green, raw	Vegetables	1 ring	1.1	Very Low	Harvard
Cauliflower, boiled	Vegetables	1 cup	1	Very Low	Harvard*
Cucumber, raw	Vegetables	1/4 cucumber	1	Very Low	Harvard*
Peas, green, boiled	Vegetables	1 cup	1	Very Low	Harvard*
Ice cream, vanilla	Dairy	1 cup	1	Very Low	Harvard*
Apple	Fruits	1 fruit	1	Very Low	UChicago
Mushrooms, variety, fresh (boiled/canned)	Vegetables	100g	1	Very Low	OHF
Kale, raw	Vegetables	1 cup	0.7	Little or None	Harvard
Apple, raw with skin	Fruits	1 fruit	0.7	Little or None	Harvard*
Watermelon	Fruits	1 slice	0.6	Little or None	Harvard*
Mango	Fruits	1 fruit	0.6	Little or None	Harvard
Wine, white	Beverages	1 cup	0.5	Little or None	Harvard*
Milk, whole	Dairy	1 cup	0.5	Little or None	Harvard*
Corn Flakes cereal	Cold Cereal	1 cup	0.5	Little or None	Harvard*
Lettuce, iceberg	Vegetables	1 cup	0.4	Little or None	Harvard*
Peach, raw	Fruits	1 fruit	0.4	Little or None	Harvard*
Yogurt, Greek, plain	Dairy	100g	0.4	Little or None	Harvard
Cheese, cheddar	Dairy	100g	0.4	Little or None	Harvard*
Lettuce, romaine	Vegetables	1 cup	0.3	Little or None	Harvard*
Bacon	Meat & Poultry	1 slice	0.3	Little or None	Harvard*
Flaxseed, ground	Nuts & Seeds	1 tbsp	0.2	Little or None	Harvard*
Salmon, cooked	Fish	100g	0.2	Little or None	Harvard*
Plum, raw	Fruits	1 fruit	0.1	Little or None	Harvard*
Coconut, dried shredded	Nuts & Seeds	1 tbsp	0.1	Little or None	Harvard*
Beef patty, broiled 85% lean	Meat & Poultry	100g	0.1	Little or None	Harvard*
Pork, loin/chops	Meat & Poultry	100g	0.1	Little or None	Harvard*
Shrimp, cooked	Fish	100g	0.1	Little or None	Harvard*
Mushroom, white raw	Vegetables	1 mushroom	0	Little or None	Harvard*
Barley, cooked pearled	Grains & Pasta	1 cup	0	Little or None	Harvard
Oat bran, raw	Grains & Pasta	1 cup	0	Little or None	Harvard*
Cola, caffeinated	Beverages	1 cup	0	Little or None	Harvard*
Water, tap	Beverages	1 cup	0	Little or None	Harvard*
Butter, salted	Dairy	1 tsp	0	Little or None	Harvard*
Chicken, roasted meat	Meat & Poultry	100g	0	Little or None	Harvard*
Turkey, roasted meat	Meat & Poultry	100g	0	Little or None	Harvard*
Cod, cooked	Fish	100g	0	Little or None	Harvard*
Egg, whole	Eggs	1 egg	0	Little or None	Harvard
Mayonnaise	Condiments	1 tbsp	0	Little or None	Harvard*
Oatmeal, instant sweetened	Hot Cereal	1 cup	0	Little or None	Harvard*

Very High (≥12 mg)High (10–11 mg)Moderate (5–9 mg)Low (3–4 mg)Very Low (1–2 mg)Little or None (0 mg)

* = Directly measured in laboratory. Categories are based on per-serving oxalate: Very High ≥12 mg, High 10–11, Moderate 5–9, Low 3–4, Very Low 1–2, None 0 mg.

Other Calculators

Oxalate in Foods

DNA Trait Analysis

Estimated Healthspan

Metabolic Health Score

Insulin Resistance (HOMA-IR)

Quick Reference

Daily limit: For kidney stone prevention, most guidelines recommend <40–50 mg oxalate/day.

Tip: Pairing high-oxalate foods with calcium-rich foods (e.g. dairy) can reduce oxalate absorption.

Cooking helps: Boiling vegetables can reduce soluble oxalate by 30–87%.

Medical Disclaimer: This database is provided for educational and informational purposes only. It does not constitute medical advice. Always consult with a qualified healthcare professional before making dietary changes, especially if you have a history of kidney stones.

Frequently Asked Questions About Oxalates and Kidney Stones

What are oxalates and why do they cause kidney stones?

Oxalates (oxalic acid) are naturally occurring compounds found in many plant foods. When oxalate binds with calcium in the kidneys, it forms calcium oxalate crystals — the most common type of kidney stone (about 80% of all cases). Reducing dietary oxalate can help prevent recurrence.

How much oxalate per day is safe for kidney stone prevention?

Most urologists and dietitians recommend keeping dietary oxalate below 40–50 mg per day for people prone to calcium oxalate kidney stones. Some stricter protocols recommend <40 mg/day. Always consult your doctor for personalised guidance.

Which foods are highest in oxalates?

The highest-oxalate foods include spinach (1,000+ mg per cup cooked), rhubarb, beets, swiss chard, almonds, dark chocolate, sweet potatoes, and navy beans. Dried figs, buckwheat flour, and some seaweed (dulse, nori) are also very high. Check our database above for the complete list.

Does cooking reduce oxalate in food?

Yes. Boiling is the most effective method and can reduce soluble oxalate by 30–87% depending on the food, because oxalate leaches into the cooking water (which should be discarded). Steaming and baking are less effective but still help. Soaking beans and grains before cooking also reduces oxalate content.

How can I reduce calcium oxalate kidney stone formation?

Key strategies include: (1) staying well hydrated (2.5–3 L of water/day), (2) following a low-oxalate diet (<40–50 mg/day), (3) eating calcium-rich foods (dairy, fortified plant milks) at the same meal as higher-oxalate foods so calcium binds oxalate in the gut, (4) boiling high-oxalate vegetables to leach oxalate into the water, and (5) limiting sodium and animal protein which can increase urinary calcium. Do not restrict calcium — low-calcium diets actually increase stone risk.

What is a low-oxalate diet?

A low-oxalate diet limits oxalate intake to under 40–50 mg per day. It focuses on choosing foods with <5 mg oxalate per serving (like white rice, eggs, dairy, most meats, cauliflower, cabbage) and avoiding very high sources (spinach, rhubarb, almonds, beets). It's important to stay well hydrated and include adequate calcium.