Healthcare providers may recommend low oxalate diets to treat a variety of conditions, particularly kidney stones.
However, recent research has called into question whether low oxalate diets are necessary for preventing kidney stones and other conditions.
This article takes a closer look at the low oxalate diet, including how it works, how to follow it, and whether it can help protect against kidney stones.
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Oxalate, also called oxalic acid, is a compound that your body produces. You can also find it naturally in many food sources, including fruits, vegetables, nuts, and grains.
Small amounts of oxalate and calcium are normally present in the urinary tract and typically do not cause any issues.
However, in some cases, calcium and oxalate can bind together and form calcium oxalate kidney stones, which are hard mineral deposits that form in the kidneys (1).
This is especially common in people who are producing small amounts of urine and excreting high amounts of oxalate (2).
For those who are prone to developing calcium oxalate kidney stones, it may be beneficial to reduce how much oxalate their body excretes through urine.
Following a low oxalate diet is one of the most common ways to do this.
However, another way to decrease your excretion of oxalate is to increase your intake of calcium, which binds with oxalate before reaching the kidneys to help prevent kidney stones (3).
SummaryConsuming high amounts of oxalate may increase how much oxalate your body excretes in urine, which may contribute to the formation of kidney stones.
How to follow a low oxalate diet
Low oxalate diets involve eating less food that’s high in oxalates. Foods high in oxalates include certain types of fruits, vegetables, nuts, grains, and legumes.
Although recommendations can vary, most healthcare providers advise limiting oxalate intake to less than 40–50 mg per day.
To stay under this limit, your diet should consist primarily of foods like proteins, dairy products, white rice, and low oxalate fruits and vegetables.
Soaking and cooking certain vegetables and legumes can reduce their oxalate content (4, 5).
Some healthcare providers may also recommend making other dietary modifications, such as drinking more water, eating more calcium-rich foods, and reducing your salt intake (6).
SummaryLow oxalate diets involve reducing your intake of oxalates, which are found in certain types of fruits, vegetables, nuts, grains, and legumes.
What to eat and avoid
Foods are typically grouped into four categories based on their content of oxalates (7):
- Very high: more than 100 mg of oxalates per serving
- High: 26–99 mg per serving
- Moderate: 10–25 mg per serving
- Low: 5–9 mg per serving
On a low oxalate diet, you should consume mostly foods that contain low to moderate amounts of oxalate and limit foods and drinks that are high in oxalate.
Foods to eat
Many foods are naturally low in oxalates, and you can enjoy them as part of a healthy, low oxalate diet.
Here are some foods you can eat on a low oxalate diet (3):
- Fruits: bananas, blackberries, blueberries, cherries, strawberries, apples, apricots, lemons, peaches
- Vegetables: mustard greens, broccoli, cabbage, cauliflower, mushrooms, onions, peas, zucchini
- Grains and starches: white rice, corn flour, oat bran
- Proteins: eggs, meat, fish, poultry
- Dairy products: yogurt, cheese, milk, butter
- Beverages: coffee, water, fruit juice
- Some herbs and spices: cinnamon cilantro, cumin, dill
Foods to avoid
A low oxalate diet limits foods that are high in oxalates, including certain types of fruits, vegetables, nuts, seeds, and starches.
Some of the foods not allowed on a low oxalate diet include (3):
- Fruits: rhubarb, kiwis, dates, raspberries, oranges, tangerines
- Vegetables: spinach, chard, potatoes, beets, turnips, yams, okra, carrots
- Legumes: navy beans, fava beans, kidney beans, refried beans
- Nuts: almonds, walnuts, macadamia nuts, cashews
- Seeds: sunflower seeds, pumpkin seeds
- Chocolate and cocoa
- Grains and starches: brown rice, couscous, millet, bulgur, cornmeal, corn grits
- Beverages: chocolate milk, hot chocolate, tea, tomato juice
- Soy products: tofu, soybeans, soy burgers
Note that soaking and cooking can significantly reduce the oxalate content of many vegetables and legumes (4, 5).
SummaryA low oxalate diet limits the intake of many types of fruits, vegetables, nuts, seeds, starches, and legumes that are high in oxalates.
Does it help prevent kidney stones?
Some research shows that increased oxalate intake may be linked to greater excretion of oxalate through the urine, which may contribute to the development of kidney stones (1).
However, increasing your intake of calcium may be an effective way to help protect against kidney stones. This approach provides an alternative to eliminating foods that are high in oxalate (6, 8).
In fact, consuming more calcium can help decrease the absorption of oxalate in your body, which could prevent kidney stones from forming (9).
One 10-person study even found that consuming high amounts of oxalate did not increase the risk of developing calcium oxalate kidney stones when participants were meeting the daily recommended intake for calcium (10).
However, this study was small, and scientists need to do more research on the topic.
Recommendations suggest aiming for 1,000–1,200 mg of calcium per day, which you can find in foods like dairy products, leafy greens, sardines, and seeds (3).
Here are a few other ways to reduce the risk of calcium oxalate kidney stones:
- Limit salt intake. Studies show that consuming high amounts of salt may be linked to a higher risk of developing kidney stones (11, 12).
- Avoid vitamin C supplements. Your body converts vitamin C into oxalate, so avoid using high-dose vitamin C supplements unless your healthcare provider recommends it (13).
- Stay hydrated. Increasing your fluid intake can increase urine output and reduce the risk of kidney stones (14).
When it comes to reducing oxalate excretion in urine, getting enough calcium in your diet may be just as effective as lowering the oxalate in your diet.
Other benefits
Some people claim that oxalates may be associated with other health problems, including autism.
In fact, one small study found that children with autism had significantly higher levels of oxalate in their blood and urine compared with a control group (15).
However, there’s no research suggesting that autism is caused by dietary oxalates or showing any potential benefit of a low oxalate diet for treating autism (16, 17).
People have also used low oxalate diets to treat vulvodynia, a condition characterized by chronic pain of the vulva (18).
Studies show that dietary oxalate consumption is not associated with a higher risk of developing vulvodynia. However, following a low oxalate diet may help with pain management (19, 20).
SummarySome people claim that dietary oxalates contribute to autism or vulvodynia, but no evidence shows that oxalate consumption directly causes either condition.
Downsides
Low oxalate diets restrict many healthy and nutritious foods, including certain types of fruits, vegetables, nuts, seeds, and starches.
For example, spinach is high in oxalates but also a great source of fiber, vitamin A, calcium, and magnesium (21).
Similarly, beets are high in oxalates but also loaded with key nutrients like folate, potassium, and manganese (22).
People with specific dietary restrictions or food preferences may also find it challenging to follow a low oxalate diet, as it limits so many foods.
Vegans and vegetarians, in particular, may have trouble eating enough protein because plant sources of protein like beans, nuts, and tofu are typically high in oxalates.
Protein deficiency can cause a range of negative side effects, including impaired immunity, weakness, anemia, and stunted growth (23).
Therefore, if you follow a low oxalate diet, you’ll need to plan carefully to ensure the diet meets your nutritional needs.
SummaryMany nutritious foods are high in oxalates. Following a low oxalate diet may be challenging for vegans and vegetarians because many plant-based sources of protein contain oxalates.
The bottom line
Oxalates are a type of compound found naturally in a variety of foods, including certain types of fruits, vegetables, beans, nuts, and grains.
Excreting high levels of oxalate through urine could contribute to the formation of calcium oxalate kidney stones.
To prevent this, some people try to eliminate oxalate from their diets, which may help lower the risk of kidney stones.
However, eating more calcium-rich foods and making other modifications to your diet is another way to help prevent kidney stones — and may be a more practical approach.