Preliminary research has tied oxalate build-up to thyroid disease, and while I’ve never had a problem with oxalates (knock on wood), other thyroid patients have reported oxalate issues.
While oxalate build-up has been predominantly tied to kidney stone formation, a study of thyroid autopsies found that 79% of adults were found to have oxalate crystals in their thyroid glands, with prevalence increasing with age.
Interestingly, people with Hashimoto’s had a lower incidence of oxalate crystals, especially in the parts of their thyroid gland that were inflamed! This led the scientists to conclude that oxalates may play a role in contributing to Hashimoto’s, potentially causing inflammation that may trigger the autoimmune response that results in the destruction of the oxalate crystals and the surrounding thyroid tissue. In some cases, giant cell reactions were found around the crystals, suggesting an ongoing immune response.1
A 2000 case report featured 4 people with a rare genetic disorder that resulted in oxalate build-up who developed hypothyroidism and highlighted the role of oxalates in causing damage to the thyroid gland, and, thus, hypothyroidism.2
To complicate things further, a 2006 study reported that a person developed excess oxalates due to hypothyroidism that was induced by amiodarone (one of the most thyroid toxic drugs)!3
Oxalate sensitivity should be suspected if you have any of the following symptoms (in addition to a thyroid condition like Hashimoto’s or Graves’):
- joint pain
- pain in the body
- burning with urination (interstitial cystitis)
- burning with bowel movements
- leaky gut
- kidney stones
Additionally, a recent study even tied excess oxalate build-up to breast cancer!4
So What are Oxalates?
Oxalate is a substance that is found in some foods and is also a waste product made by our bodies and excreted through our kidneys. While a standard diet takes in about 250 mg of oxalates, when eating a low oxalate diet, consuming under 100 mg is recommended, but under 50 mg is ideal, unless your doctor suggests otherwise.
Oxalates form salts in the body by combining with calcium, after we consume plants that have a high oxalate content (such as dark leafy greens). When our body can’t process the calcium-oxalate compounds, they crystallize and lodge in our organs, causing inflammation and/or can turn into painful kidney stones.
Oxalates in Food
The top ten foods with the highest oxalate content per serving include
- Rice bran
- Miso soup
- Wheat berries
- Navy beans
The other foods that are commonly eaten on a Paleo diet that have oxalate content above 50 mg per serving include baked potatoes, beets, cocoa powder, and okra. Raspberries come in close, at 48 mg per serving!
There are some foods that have an ultra high oxalate content. However, we use them sparingly (like black pepper). These foods are usually not as much of a concern unless you are using more than 1 tsp at a time (that’s a lot of pepper!).
Testing for Oxalate Build-Up
The Organix Dysbiosis Marker test kit from Genova and Great Plains Labs can detect oxalate issues (you can self-order this test or get it from your functional practitioner).5
Conventional doctors can also run a urinary oxalate test. Here’s a link to the test overview.6
In people that don’t properly break them down, oxalates can cause kidney stones! If a person is passing kidney stones, the stones can be tested to see if they contain calcium oxalate. If this test is positive, a low oxalate diet should be followed to help prevent the formation of more kidney stones.7
I think the least expensive and most effective test (especially if you’re having symptoms) is a trial of the low oxalate diet.
Low Oxalate Diet
While it would be best to limit all foods that contain oxalates, it’s not ideal or realistic to stop them all at once. It’s also not going to make a person feel well. Once you stop eating the oxalates, your body is going to detox, and you may go through a period of “oxalate dumping,” where too many oxalates try to leave your body all at once and cause unpleasant symptoms.
Start by eating moderate oxalate foods for one week (reduce your intake to less than 100 mg of oxalates per day). Let the body adjust, and then go to low oxalate foods (less than 50 mg of oxalates per day). When a higher oxalate food is consumed, it should be rotated, to avoid over-concentration of oxalates and sensitivity to that food.
Once a person feels better, it’s easy to slowly let high oxalate foods creep back in. These foods should always be rotated. If symptoms return, it’s important to reduce oxalate intake immediately, to avoid possible stone formation.
Here is an overview of High, Medium, and Low Oxalate foods