Oxalates, also known as oxalic acid, are naturally occurring compounds in plants. We eat them in food and our bodies make them as well.
Leafy greens, legumes, and other foods high in oxalates are rich in beneficial nutrients. 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. But for most people, the benefits of nutrient-dense, high-oxalate foods can outweigh their risks.
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.
2. Soy products
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 3-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.
6. Navy beans
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.
Problems From High-Oxalate Levels
Increased risk of kidney stones: About 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, excess amounts can prevent your body from absorbing other beneficial nutrients in your digestive tract.
Other issues can contribute to the problem. For example, your gut breaks down many oxalates. But when you take antibiotics, they can lessen the good bacteria in your gut that helps do this. That can lead oxalates to build up.
Bacteria known as Oxalobacter formigenes rely on oxalates as a source of energy, which helps lessen oxalate buildup. Some people have more of this bacteria than others. Antibiotics can be especially hard in this type of bacteria, leading to quick oxalate buildup.·
People who have had gastric bypass surgery or surgeries that affect how the gut works may also have high oxalate levels in their urine. If you have gut dysfunction or take antibiotics, you may want to eat a low-oxalate diet.
Avoid High-Oxalate Levels
There are things you can do to help keep lower high oxalate levels and lessen the problems they can cause:
- Balance high-oxalate foods with other fruits and vegetables to help ensure good health.
- Drink enough water to help your body flush out excess oxalates.
- Get the recommended amount of calcium, which binds to oxalates during digestion.
- Limit sodium and sugar intake, which may contribute to kidney stones at high levels.
- Get the recommended amount of vitamin C. Too much can increase oxalic acid production in your body.
- Cook high-oxalate vegetables to lower their oxalate content. Boiling works especially well for this.
Research shows that restricting foods with high oxalates may no longer be practical. Most of these foods contain healthy nutrients that the body needs. Also, a large portion of the oxalate in urine comes from the body and not from food. Still, in some cases, your doctor may suggest you try a low-oxalate diet.
Most people get between 200 and 300 milligrams of oxalates daily. If you’re at risk for kidney stones, sources suggest getting 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.
Here are eight low-oxalate foods you could add to your diet:
1. Kale and bok 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.
2. 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.
3. 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.
4. Sweet potatoes
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.
6. Kidney beans
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.
7. 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.
8. Dried figs
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.