Oxalate foods

Oxalate is a naturally-occurring organic compound found in a wide variety of foods. Oxalates are also produced in our body and the metabolism of Vitamin C also results in the production of oxalates.
Oxalate binds to minerals to form compounds such as calcium oxalate and iron oxalate in the large intestine of our body. This can also take place in the kidneys and other parts of the urinary tract where it is produced as a waste product.
Generally, it is eliminated along with the stool or urine. But in the case of sensitive individuals, high-oxalate diets cause an increased risk of formation of kidney stones and other health problems.

The health concern regarding oxalate is that it binds to minerals in the gut and prevents the body from absorbing them. But, gut bacteria break down some of the oxalates of food before they bind to minerals.

Only in soluble forms, oxalates are absorbed from the digestive tract. The combination of foods influences the absorption of soluble oxalates from the digestive tract.

A combination of high calcium and high oxalate foods such as low fat cheese with a spinach salad or yogurt with berries will not affect the nutrient absorption from the gut. Instead of calcium foods, calcium supplements like calcium citrate can be taken along with high oxalate foods.

Oxalates are found in almost all plants, but some plants contain very high amounts while others have very little. Animal foods contain only trace amounts of oxalates.

Foods rich in Oxalate are

Beans, berries, beet greens, beets, bran flakes, chocolate, cocoa powder, coffee, dark green vegetables such as spinach, kale, nuts and nut butters, oranges, french fries, potato chips, rhubarb, soda (cola), soy beans, soy milk, star fruit, sweet potatoes, tea (black), tofu, turnip greens, wheat bran.

Among all foods, Spinach (cooked or raw) has the highest amount of oxalates. (750-800 mg)
Plant leaves contain higher oxalate levels than roots, stems, and stalks.

Foods with medium oxalate are:

Blackberries, blueberries, bratwurst, bacon, bagels, brown rice, carrots, celery, cornbread, green beans, hot dogs, mangoes, noodles, pastas, parsnips, prune, sausage, summer squash, spaghetti, saltine or soda crackers, tomatoes, and turnips, vanilla wafers, white bread and white english muffins,

Foods low in oxalate are:

Animal foods such as canned fish with bones, chicken, eggs and egg noodles, meat, and seafood such as flounder, salmon, tuna, shrimp, scallops and turkey.
Fruits such as Apples, avocados, cherries, cranberries, melons, peaches, plums and seedless grapes (red and green).
Asparagus, apple juice, apple cider, barley,  broccoli, beer, butter, buttermilk, black-eyed peas, basil, cilantro, canola, cauliflower, chamomile tea, corn syrup, cucumbers, cooked and dry cereals without nuts or bran, cheese, coconut, cow’s and goat’s milk, flax seeds, green peas, ginger ale, honey, iceberg, maple syrup, margarine,  mustard, mayonnaise, mushrooms, nutmeg, onions (yellow and white), plain yogurt, romaine lettuce, radishes, red sweet peppers, salt, saffron, squash, safflower, skim milk,  soy, spring and filtered water, sugar (white), turnips (root), tarragon, vanilla, vinegar, all vegetable oils, including olive, water chestnuts, white and wild rice, white pepper, white chocolate, and yellow split peas.

Pros and Cons

As most plant foods contain oxalates, their intake is practically unavoidable. Many foods that contain oxalates are nutritious, delicious and have several health benefits. Foods that contain oxalates are healthy as they contain important antioxidants, fibre and other nutrients.
So, such foods should not be avoided even though they are harmful.
The risk of kidney stone formation does not appear in healthy persons. So, healthy people should not stop the consumption of high-oxalate foods and they have to consume oxalate-rich foods without problems.
Normally, calcium and small amounts of oxalate are present in the urinary tract of all people in dissolved form and cause no problems. Only in some people, they bind to form crystals and these crystals can lead to the formation of stones, especially when oxalate is high and urine volume is low. In such persons, high-oxalate foods may increase the risk of kidney stones.
Diets low in oxalates and antibiotics cause beneficial gut microorganisms to die and cause the person to become more sensitive to the effects of oxalates.

People suffering from inflammatory bowel disease have an increased risk of developing kidney stones because they are unable to regulate the amount of oxalate they absorb.
About 80% of kidney stones are made up of calcium oxalate. So, people who have calcium oxalate kidney stones are advised to minimize their consumption of foods high in oxalates.
Persons with health histories of kidney stones, may suffer from conditions like hypercalciuria type II, enteric hyperoxaluria, and primary hyperoxaluria due to the intake of high oxalate foods.
A high oxalate food intake may also lead to the development of autism and vaginal pain (vulvodynia).