A wide range of foods, mostly of plant origin, contain various amounts of the natural compound oxalic acid. Your body metabolizes this compound into a form of salt called oxalate, which serves no known purpose in the human body. Consequently, more than 90 percent of oxalate is filtered out by the kidneys for urinary excretion. High amounts of dietary oxalate may contribute to the formation of oxalate-containing kidney stones in those prone to forming them. A low-oxalate diet generally restricts oxalate intake to no more than 50 milligrams per day. Brown rice is classified as a moderate-oxalate food, meaning it can be consumed in moderate amounts on a low-oxalate diet.
Oxalate-containing foods are broadly categorized as high, moderate or low in oxalate. High-oxalate foods, including spinach and chocolate, provide more than 10 milligrams per serving, while moderate-oxalate foods such as brown rice contain between two and 10 milligrams per serving. Foods qualifying as low in oxalate supply less than two milligrams per serving. A food’s oxalate content can be highly variable, depending on its state of ripeness and the soil and climate in which it was grown. As a result, foods are categorized based on their highest reported oxalate value, according to the “Encyclopedia of Healing Foods.”
A 100-gram serving of cooked brown rice, or roughly one-half cup, contains between 2 and 10 milligrams of oxalate, qualifying it as a moderate source of oxalate. Low-oxalate dietary guidelines generally recommend limiting moderate-oxalate foods to two or three servings per day and avoiding high-oxalate foods. The diet does not restrict the intake of low-oxalate foods. Eating a half-cup serving of brown rice — plus up to two more servings of foods from the moderate-oxalate category — falls within these general recommendations and is considered safe on a low-oxalate diet. White rice and wild rice are low-oxalate foods.
Although restricting dietary oxalate is generally considered effective for reducing the occurrence of oxalate-containing kidney stones, several studies suggest that consuming foods containing both oxalate and calcium may actually reduce kidney stone formation, according to the University of Maryland Medical Center. Increasing your intake of foods with a high magnesium-to-calcium ratio, such as brown rice, avocados and bananas, may help reduce oxalate-containing stones, according to the “Encyclopedia of Healing Foods.” Decreasing your intake of animal protein while consuming 12 to 16 cups of water per day can also have a significant impact on stone production.
Even if you have a medical history of oxalate-containing kidney stones, you shouldn’t go on a low-oxalate diet unless instructed to do so by your physician. Many high- to moderate-oxalate foods are important sources of nutrition that shouldn’t be excluded from your diet unless medically necessary. If your health-care provider does recommend that you restrict your oxalate intake, ask for a comprehensive list of foods and their oxalate values, as well as the specific parameters of your diet. If you routinely enjoy moderate-oxalate foods such as brown rice, ask your physician how much you can safely consume in a day.
Articles For Your Diet
- University of Maryland Medical Center: Kidney Stones - Prevention
- National Kidney and Urologic Diseases Information Clearinghouse: Diet for Kidney Stone Prevention
- UPMC: Low Oxalate Diet
- Oxalosis and Hyperoxaluria Foundation: What is Hyperoxaluria and Oxalosis?
- Encyclopedia of Healing Foods; Michael Murray, N.D., et al.
- Bowl of Rice image by Eric Holsinger from Fotolia.com