Quick Tips to Start a Low-Oxalate Diet
Following a low-oxalate diet means keeping your daily oxalate intake to around 40 to 50 milligrams (mg). Some experts suggest that up to 100 mg per day is acceptable. You don’t always have to avoid high-oxalate foods completely; the key is to focus mainly on low-oxalate foods and occasionally include medium- or high-oxalate items.
Spinach is the highest in oxalate among vegetables and fruits—over 100 times higher than most high-oxalate foods. Therefore, it’s best to avoid spinach entirely on this diet!
Most legumes are high in oxalate, but soaking them can draw the oxalate into the water, which you then discard. Boiling vegetables can reduce their oxalate content by 30 to 90 percent. Additionally, aim to consume 800 to 1,200 mg of calcium daily, as this can reduce how much oxalate is absorbed into your bloodstream. Be mindful of your sodium intake, as high sodium can increase calcium levels in your urine, which can lead to stone formation. If you’re male, it’s best to avoid high doses of vitamin C as this can increase the risk of stone formation.
What Is Oxalate?
Oxalic acid is a molecule produced naturally by plants and humans, thus it’s present in many plant foods. When oxalic acid binds to minerals like calcium, it forms oxalate. Oxalate is not a nutrient; rather, it’s sometimes called an anti-nutrient because it prevents the body from using the minerals it binds to. Oxalate exists as an insoluble crystal which, when small, is easily excreted from the body. However, when these crystals grow in size, they become kidney stones, which are painful and difficult to pass. Although other types of kidney stones exist, those formed from oxalate are the most common.
What Increases Oxalate Levels?
Men who consume more than 1,000 mg of vitamin C daily have a higher risk of forming calcium oxalate kidney stones, as the body converts vitamin C (ascorbic acid) into oxalate. Antibiotics can also increase oxalate levels by killing the good gut bacteria that help degrade oxalate. A high-oxalate diet naturally increases oxalate levels in the bloodstream and urine, so those prone to kidney stones may benefit from following a low-oxalate diet.
What Is a Low-Oxalate Diet?
A low-oxalate diet focuses on foods low in oxalate and is often recommended by healthcare providers for preventing kidney stones. While the average diet contains about 70 to 150 mg of oxalate per day, a low-oxalate diet typically aims for 40 to 50 mg daily, though up to 100 mg is considered acceptable by some nutritionists.
What Can You Eat?
On a low-oxalate diet, it’s crucial to manage your overall oxalate intake rather than completely avoiding higher-oxalate foods. Aim to keep your daily intake below 40 to 50 mg. Portion size is also critical; for instance, adding a tablespoon of high-oxalate sunflower seeds to a salad can be acceptable as the portion is small.
Low-Oxalate Vegetables
These vegetables are good choices for someone on a low-oxalate diet:
- Green pepper: 1/2 cup, 5 mg
- Mustard greens: 1 cup, 4 mg
- Yellow squash: 1/2 cup, 4 mg
- Cucumber: 1/2 fruit, 2 mg
- Kale: 1 cup, 2 mg
- Bok choy: 1 cup, 1 mg
- Cabbage: 1/2 cup, 1 mg
- Cauliflower: 1/2 cup, 1 mg
- Peas: 1/2 cup, 1 mg
- Zucchini: 1/2 cup, 1 mg
- Chives: 1 teaspoon, 0 mg
- Onions: 1 small onion, 0 mg
- Romaine lettuce: 1 cup, 0 mg
Low-Oxalate Fruits
These fruits are also low in oxalate:
- Pineapple: 1 cup, 4 mg
- Bananas: 1 fruit, 3 mg
- Cherries: 1 cup, 3 mg
- Limes: 1/2 fruit, 3 mg
- Raisins: 1 ounce (1 small box), 3 mg
- Blueberries: 1/2 cup, 2 mg
- Pears: 1 fruit, 2 mg
- Cantaloupes: 1/2 melon, 2 mg
- Strawberries: 1/2 cup, 2 mg
- Apples: 1 fruit, 1 mg
- Grapes: 1/2 cup, 1 mg
- Mangoes: 1 fruit, 1 mg
- Peaches: 1/2 fruit, 1 mg
- Watermelon: 1 slice, 1 mg
Low-Oxalate Bread, Cereal, & Grains
Healthy grain options are limited but still available for those following a low-oxalate diet. High-oxalate grains like processed white flour, wheat flour, and brown rice flour should be avoided.
- Whole oat bread: 1 slice, 5 mg
- Oatmeal: 1 cup, 0 mg
Low-Oxalate Protein Sources
Plant-based protein sources are abundant and sustainable choices. Soaking legumes can help reduce their oxalate content.
- Fava beans: 1/2 cup, 20 mg
- Refried beans: 1/2 cup, 16 mg
- Red kidney beans: 1/2 cup, 15 mg
- Lentils: 1/2 cup, 5-10 mg
- Garbanzo beans: 1/4 cup, 5-10 mg
- Mung beans: 1/2 cup, 8 mg
- Raw coconut meat: 1/4 cup, less than 5 mg
- Black-eyed peas: 1/2 cup, less than 5 mg
- Split peas: 1/2 cup, 5-10 mg
- Lima beans: 1/2 cup, 5-10 mg
Low-Oxalate Drinks
Water is always the best choice, especially for preventing kidney stones. Here are some low-oxalate drink options:
- Water infused with lemon: 1 cup, 0 mg
- Pineapple juice: 8 oz., 3 mg
- 100% Cranberry or Cran-apple juice: 1/2 cup, less than 5 mg
- Grapefruit juice: 1/2 cup, less than 5 mg
- Apple juice: 1/2 cup, less than 5 mg
- Brewed coffee: 1 cup, less than 5 mg
- Herbal tea: 2 cups, less than 5 mg
- Wine: 1 cup, less than 5 mg
High-Calcium Foods to Eat
Don’t let the term “calcium oxalate stones” fool you into avoiding calcium. Increased calcium intake can actually help reduce oxalate levels in the body. When calcium binds to oxalate in the intestines, it gets excreted in the stool before reaching the kidneys.
Adding high-calcium foods to your meals helps minimize oxalate absorption. Try to include two to three servings of calcium with each meal, especially if you’re consuming a high-oxalate food. Though controversial, some studies suggest that calcium supplements can lead to higher stone formation rates in people prone to kidney stones. It’s often best to get calcium from food or take supplements with meals to minimize risks.
Avoid These High-Oxalate Foods
While following a low-oxalate diet, you’ll need to limit certain high-oxalate foods. Here’s a quick list of high-oxalate foods to avoid regularly:
- Spinach, raw: 1/2 cup, 656 mg
- Rhubarb: 1/2 cup, 541 mg
- Buckwheat groats: 1 cup, 133 mg
- Almonds: 1 ounce (22 nuts), 122 mg
- Corn grits: 1 cup, 97 mg
- Baked potato with skin: 1 potato, 97 mg
- Beets: 1/2 cup, 76 mg
- Navy beans: 1/2 cup, 76 mg
- Cocoa powder: 4 teaspoons, 67 mg
- Cornmeal: 1 cup, 64 mg
- Okra: 1/2 cup, 57 mg
- Cashews: 1 ounce (18 nuts), 49 mg
- Raspberries: 1 cup, 48 mg
- Soybeans: 1/2 cup, 48 mg
- Walnuts: 1 cup, 31 mg
- Dried pineapples: 1/2 cup, 30 mg
- Orange: 1 fruit, 29 mg
- Sweet potato with skin: 1 cup, 28 mg
- Grapefruit: 1 fruit, 24 mg
- Soy milk: 1 cup, 20 mg
- Avocados: 1 fruit, 19 mg
- Celery: 1/2 cup, 19 mg
- Pumpkin seeds: 1 cup, 17 mg
- Black tea: 1 cup, 14 mg
Some foods, despite their high oxalate content, raise urine oxalate levels more significantly than others. These include spinach, rhubarb, beets, nuts, chocolate, tea, wheat bran, and strawberries. While nutritious, these foods are best avoided on a low-oxalate diet.
Low-Oxalate Diet Meal Plan
Here is an example of what a low-oxalate diet might look like:
Day One
Breakfast: Chickpea scramble, coffee
Lunch: Greek salad with cucumbers, tomatoes, and raw organic goat cheese with vinaigrette dressing
Dinner: Lentil chili, sliced pineapple for dessert
Day Two
Breakfast: Plain coconut milk yogurt with sliced banana and blueberries, coffee
Lunch: Roasted butternut squash topped with raw organic goat cheese
Dinner: Cooked black-eyed peas tossed with sautéed celery, red peppers, and onions in a vinaigrette dressing, fresh cherries for dessert
Day Three
Breakfast: Blueberry smoothie with banana and pea protein
Lunch: Romaine lettuce salad with avocado, cucumbers, mushrooms, and vinaigrette dressing
Dinner: Pumpkin soup
Other Natural Ways to Reduce Oxalate
Here are a few more tips to help you manage oxalate levels:
Drink Plenty of Water
Increasing your water intake dilutes substances in your urine that can cause kidney stones. The extra fluid helps you urinate more, which makes it less likely for oxalate to settle in your kidneys and form stones. Studies suggest that producing 2 to 2.5 liters of urine daily can cut kidney stone risk by 50 percent. This means drinking about eight to ten 8-ounce glasses of water each day.
Reduce Salt Intake
Excessive salt intake can increase calcium levels in your urine, leading to a higher risk of stone formation. Try to limit your daily salt intake to 1,500 mg by reading nutrition labels and avoiding high-sodium foods like canned goods, fast food, and deli meats.
Limit Vitamin C Supplements
Men taking 1,000 mg of vitamin C supplements daily have a higher risk of developing calcium oxalate stones, so it’s advisable to limit these supplements. Dietary vitamin C from food does not carry the same risk and is generally safe.
Consume More Citric Acid
Citric acid, found in many fruits and vegetables like lemons and limes, binds with calcium in urine, preventing it from forming oxalate stones. It also binds to existing calcium oxalate crystals, making them easier to excrete.
How to Get Started
Start by keeping a food diary and using online resources to calculate your typical oxalate intake. Look at charts of low-oxalate foods and find opportunities to replace higher-oxalate foods. Gradually switch from high-oxalate to moderate-oxalate foods, and then to low-oxalate ones.
Points to Remember
Oxalate forms when oxalic acid in plants binds with a mineral such as calcium and can create kidney stones in some people. A low-oxalate diet can help reduce your risk of developing these stones. Aim to keep your oxalate intake around 50 to 100 mg by using available food charts. Besides following a low-oxalate diet, increase your water, calcium, and citric acid consumption while reducing your salt intake.
If kidney stones are a concern, check out additional resources for more tips on maintaining healthy kidney function.
