Oxalates — also known as oxalic acid — is a naturally-occurring compound in plants. These plant-based oxalates are consumed through our diet as well as produced as waste by your bodies.
Various foods high in oxalates are rich in many nutrients beneficial to your health, like leafy greens and legumes. However, because oxalates bind to calcium as they leave the body, they can increase the risk of kidney stones in some people.
If you’re prone to kidney stones or have kidney disease, your doctor may recommend you follow a low-oxalate diet. However, for most people, the benefits of nutrient-dense, high-oxalate foods can outweigh their risks.
Why You Should Avoid Oxalates
Your body naturally gets rid of oxalates, but in high amounts, they can have adverse effects. However, since foods containing oxalates are often nutritious in other ways, you shouldn’t remove them from your diet altogether.
Most people get between 200 and 300 milligrams of oxalates daily. If you’re at risk for kidney stones, sources suggest consuming less than 100 milligrams a day. Doctors may also recommend “low-oxalate diets” of less than 50 milligrams daily for some people. Talk to your doctor about what diet is best for your health.
A diet high in oxalates may have some negative effects, including:
Increased Risk of Kidney Stones
Estimates show that 1 in 10 people are affected by kidney stones, though some people are at more risk than others. When oxalate levels are high, there’s a greater chance it will bind to calcium, forming kidney stones.
Lower Mineral Absorption
Because oxalates bind to minerals like calcium, they can prevent your body from absorbing beneficial nutrients in your digestive tract . Yet, they don’t block absorption completely, and our bodies only use a portion of the nutrients we consume.
Some of the oxalates you consume are broken down in your gut, reducing the amount that passes through your digestive and urinary systems. However, when you take antibiotics, this effect is reduced. Antibiotics decrease the good bacteria in our gut that absorb oxalates, which can enhance their activity.
Foods With Oxalates
Most plant-based foods contain oxalates but are also rich in a range of essential vitamins and minerals. Balancing high-oxalate foods with other fruits and vegetables can ensure you’re getting adequate nutrition in your diet.
Good dietary and lifestyle choices can also reduce the impact of oxalates. This includes:
- Drinking plenty of water to help your body flush oxalates out
- Consuming enough calcium, which binds to oxalates during digestion
- Limiting sodium and sugar intake, which may contribute to kidney stones at high levels
- Getting the recommended amounts of vitamin C — too much can increase oxalic acid production in your body
- Cooking some vegetables can lower their oxalate content
High oxalate foods include:
Leafy greens like spinach contain many vitamins and minerals, but they’re also high in oxalates. A half-cup of cooked spinach contains 755 milligrams.
Products made from soybeans are excellent sources of protein and other nutrients, especially for people on a plant-based diet. However, they are also high in oxalates. A three-ounce serving of firm tofu has 235 milligrams, while 1 cup of soy milk or yogurt can have up to 336 milligrams per serving.
Almonds are concentrated with a range of vitamins and minerals, yet, they are also high in oxalates. One ounce of almonds, or about 22 nuts, contains 122 milligrams of oxalates.
A medium baked potato has 97 milligrams of oxalates per serving. Much of this content is in the potato’s skin, which contains high levels of nutrients like fiber, vitamin C, and B vitamins.
Beets are an excellent source of nutrients like folate and manganese. Research shows their nitric oxide content helps lower your blood pressure. At 152 milligrams per cup, they’re also one of the vegetables highest in oxalates.
Legumes are a great way to add protein, fiber, and other nutrients to any meal. However, if you’re managing your oxalate levels, navy beans are on the high end with 76 milligrams per half-cup.
Many fruits contain some oxalates, like avocados, oranges, and grapefruit, but raspberries are considered a high-oxalate food with 48 milligrams per cup.
Dates are highly nutritious dried fruits often used as a sweetener in cooking and baking. Date consumption should be moderated, however, as they are high in sugar and concentrated with oxalates with one date containing 24 milligrams.
Here are 8 low-oxalate alternatives to add to your diet:
Kale and Boc Choy
If you’re watching your intake of oxalates, kale and bok choy are nutrient-rich greens with just 2 milligrams and 1 milligram of oxalates per cup, respectively.
Cashews, Peanuts, and Walnuts
Compared to almonds, nuts like cashews, peanuts, and walnuts have slightly lower levels of oxalates at about 30 milligrams per ounce.
Pumpkin and Sunflower Seeds
One ounce of pumpkin and sunflower seeds contain less than 2 milligrams of oxalates. They’re also a good source of vitamin E, magnesium, and protein.
You can swap your baked potato for sweet potatoes, which are higher in most vitamins and minerals and only have 28 milligrams of oxalates per cup.
Broccoli is a delicious low-oxalate vegetable — at just 2 milligrams per cup. It’s also a good source of fiber and protein and contains many important nutrients and vitamins.
Kidney beans are a good substitute for navy beans with only 15 milligrams per half-cup. They’re also a rich source of protein and fiber.
Blueberries and Blackberries
Mix other berries in with your raspberries to reduce your oxalate intake. Blueberries and blackberries have only 4 milligrams of oxalates per cup. They’re also rich in antioxidants which can help prevent diseases such as heart disease and cancer.
For a sweet fix that’s lower in oxalates, try dried figs, which have one-fifth of the dates’ content. They’re also high in fiber, potassium, iron, and calcium.