Oxalate and Kidney Stones
Oxalate is a naturally occurring compound found in plants. Many of the foods we eat contain some amount of oxalate. A high oxalate diet can put you at risk for kidney stones. Below are steps to see if oxalates are increasing your risk for kidney stones.
Figure out if oxalate is contributing to your kidney stones
Just because you have calcium oxalate stones doesn’t mean oxalate is the cause. High urine oxalate is not a risk factor for everyone with kidney stones. In fact the most common cause of calcium oxalate kidney stones is high urine calcium. A 24 hour urine test will determine if high urine oxalate is the cause of your kidney stones. This test will also determine what dietary changes will prevent your kidney stones. The best diet to prevent kidney stones is different for each person. Ask your medical professional about a 24 hour urine test.
If you have high urine oxalate
The oxalate in your diet is one of many factors. Many other parts of your diet impact oxalate urine levels.
Four ways to lower oxalate in the urine, in order of importance
Eat enough calcium
Calcium binds to oxalate and reduces oxalate absorption in the gut. Ideally eat three servings of high calcium foods, one with each meal. This is the most effective way to lower urine oxalate.
Avoid vitamin C supplements
Your liver can make oxalate from too much vitamin C. While it is hard to get excess vitamin C from food, it is easy to get too much from supplements. Do not take vitamin C supplements.
Avoid very high oxalate foods
Avoiding foods highest in oxalate and eating enough calcium is enough to lower urine oxalate in most people. Spinach, almonds, chocolate, rhubarb, beets and navy beans are much higher in oxalate than nearly any other food. If this is not enough to lower your urine oxalate, see your medical professional. You may be advised to see a dietitian or nutrition counselor.
Don’t eat too much protein
Your liver can also make oxalate from excess protein. This is particularly true for beef, pork, chicken and fish. Ask your medical provider or dietitian how much protein is right for you.
What to do if your urine oxalate is not high
If you do not have high urine oxalate on a 24 hour urine test, a low oxalate diet will not prevent your kidney stones. There are likely other reasons you are forming kidney stones. The 24 hour urine test will reveal why you are making kidney stones. Your urine risk factors will reveal many other dietary changes you can make to reduce your chances of forming another stone.
There are many oxalate food lists available. They can vary quite a bit. Oxalate is very difficult to measure in food and varies based on where the food was grown, the type of soil, harvest time and ripeness of food. It is impossible to know exactly how much oxalate is in different foods. Therefore it is best to choose one oxalate list and focus on avoiding high oxalate foods. It is unnecessary to compare the hundreds of oxalate list available on the internet. Your time is better spent working on a diet to lower oxalate foods.
The list below is based on the oxalate list from Harvard Medical School in 2002. The portions have been standardized to make it easier to compare foods. The Harvard list is widely recognized to be the most accurate and up to date by medical professionals.
Tracking the amount of oxalate you eat every day is not necessary for most people. Avoid very high oxalate foods, eat a variety of foods, get in your calcium, and you will decrease your risk of kidney stones.
Reference: The Kidney Dietitian, Melanie Betz MS, RDPrint Page
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