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Eating your leafy greens is vital for a healthy body. However, the very vegetables that so many health-conscious people eat contain a compound that may negatively affect some people. Oxalates are an acid found in these vegetables and produced in the body. In high quantities, it may cause problems like kidney stones and nutrient depletion. Some research even points to potential issues in people with thyroid disease. Here, we explore how oxalates affect your thyroid function and whole-body health.

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Oxalates, or oxalic acid, are molecules found in natural foods and are also produced as a metabolic waste product in the body. When oxalates combine with calcium from our diet, they can create salts that crystallize and block specific organs. Most notably, oxalates increase your risk of kidney stones. However, they may also be responsible for stone formation in other parts of the body like the urinary tract and the colon.

We usually excrete oxalates through the stool or urine. However, in high quantities and susceptible individuals, they can build up in the body over time, causing inflammation and pain.

These compounds are not only found in cruciferous vegetables but also other vegetables, fruits, nuts, seeds, and cocoa. For example, foods with the highest oxalate levels include rhubarb, beets, spinach, rice bran, buckwheat, and almonds.

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An antinutrient is a natural or synthetic compound from our food that interferes with nutrient absorption. Essentially, these compounds prevent our gastrointestinal system from getting nutrients from other foods we eat. Many plants contain oxalates to prevent bacterial infections and ward off insect pests. 

Oxalates are sometimes a known antinutrient because they may interfere with mineral absorption in the digestive tract. Specifically, oxalates bind to calcium from plant sources like spinach, meaning that you may not get the full nutritional benefit of eating spinach. But intriguingly, oxalates do not attach to calcium from dairy sources like milk, so if you have a varied diet, you may not be as susceptible to a calcium deficiency compared to people who eat primarily plant-based. 

Oxalates also bind to fiber, which may affect your gut microbiome. The microorganisms in our gut primarily rely on fiber for a healthy ecosystem

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Hyperoxaluria is a medical condition where a person has high levels of oxalates in their urine. Usually, a high excretion of this compound is indicative that a person may be at risk of developing a kidney stone. 

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There are two types of hyperoxaluria: primary and secondary.

Primary hyperoxaluria is a rare genetic condition that starts at birth where the liver lacks an enzyme that helps keep oxalate levels low. When lacking, this enzyme can build oxalates in the kidneys and form kidney stones and crystals. Eventually, it can lead to oxalosis, where the kidneys can no longer excrete oxalates, and stones form in other tissues, including the blood vessels, heart, and bones. 

Secondary hyperoxaluria is more common than primary and is caused by non-genetic factors. Diet and an unhealthy gut microbiome can lead to secondary hyperoxaluria.

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So far, we haven't touched on the thyroid gland yet, as the kidneys are the primary focus of hyperoxaluria. And while most oxalate build-up occurs in the kidneys, studies have found stones in the thyroid.

In an older study on calcium oxalate crystals, 79% of adults were found to have crystals in the thyroid gland. Intriguingly, people with Hashimoto's thyroiditis had a lower prevalence of crystals than individuals with other thyroid conditions. While this may seem surprising, the researchers concluded that stone formation might trigger an increased inflammatory response, which, in turn, could destroy oxalate crystals in the gland.

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At the root of most chronic diseases is inflammation. The body uses inflammation to heal tissues and restore them to their healthy, normal functioning. However, it can lead to permanent tissue damage when it becomes a chronic problem or when misused.

Numerous factors can trigger inflammation, but some of the most common culprits include:

• Exposure to toxins
• Untreated acute inflammation, and
• Autoimmune diseases.

People with autoimmune conditions like Hashimoto's thyroiditis may be at greater risk for oxalate build-up because malabsorption issues and toxins leaking out of the gut are common. Individuals with a damaged gut lining are likely to have increased absorption of oxalates. And, if a person has an increased amount of oxalates, it could exacerbate thyroid inflammation.

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One of the best ways to reduce oxalate levels is to focus on your gut health. The gut is the primary site where we filter oxalates from food, and our gut bacteria play an important role in oxalate excretion. We have a bacterial species, Oxalobacter formigenes, which uses oxalates as its energy source.

While removing oxalate foods from the diet may seem like an obvious answer to reducing build-up, eliminating these foods may also be detrimental to our health. Often, foods like leafy greens are rich in vitamins, minerals, and fiber - which are key to a healthy gut and body. However, because oxalate-rich foods can sometimes block calcium, it may help increase your calcium intake in other ways, such as by taking a calcium supplement or getting it through dairy products.

Therefore, eating foods that nourish healthy bacteria in the gut is an important step in reducing oxalate build-up in the body. Additionally, decreasing gut inflammation may also reduce oxalate content. For example, people with Hashimoto's often have gluten sensitivity, so avoiding gluten may help reduce inflammation in the digestive tract. 

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Some people may also benefit from a low oxalate diet, especially if they have primary or secondary hyperoxaluria. 

A note from Paloma Health

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More research is needed to understand how oxalates impact the thyroid gland, especially in people with conditions like Hashimoto's disease. If you have Hashimoto's and feel like you are doing everything right but still have symptoms, meet with a thyroid doctor specializing in Hashimoto's. Paloma Health thyroid doctors take a holistic approach to treating your whole person.