How oxalates affect Thyroid Health?
Oxalates are naturally occurring molecules found in some foods and are also a waste product produced by our bodies and excreted through our kidneys. Oxalates form salts in the body by combining with calcium, after consuming foods that are high in oxalate.
When our bodies are unable to process calcium oxalate compounds, they crystallize and lodge in our organs, causing inflammation, which can turn into painful kidney stones and lead to other inflammatory symptoms from the buildup of oxalate in the body, such as joint pain, pain when urinating / bowel movements and even inflammation of the thyroid gland.
The most common foods with the highest oxalate content per serving are rhubarb, rice bran, buckwheat, almonds, miso soup, wheat berries, corn, potatoes, beans, beets, cocoa powder, and raspberries.
Types of hyperoxaluria
There are two different types of hyperoxaluria: primary hyperoxaluria and secondary hyperoxaluria.
Primary hyperoxaluria occurs when there is a hereditary or genetic defect in the function of the enzymes that carry out the metabolism of oxalate. It is a rare genetic and metabolic disease. (Within primary hyperoxaluria, there are three subtypes: types I, II, and III, each of which has a genetic defect in a different enzyme along the oxalate metabolism pathway.)
Secondary hyperoxaluria occurs due to non-genetic factors. Within secondary hyperoxaluria, there are two other subtypes: dietary hyperoxaluria (caused by increased consumption of oxalate-containing foods) and enteric hyperoxaluria (caused by changes in the gut microbiome).
Secondary hyperoxaluria is more common in people with Hashimoto's disease because this autoimmune disorder is often associated with changes in the gut microbiome and many people on a thyroid-healing diet may consume large amounts of oxalate-rich fruits/vegetables.
How do oxalates impact thyroid health?
Interestingly, people with Hashimoto's had a lower incidence of oxalate crystals, especially in the inflamed parts of their thyroid!
This led scientists to conclude that oxalates may play a role in Hashimoto's disease, possibly causing inflammation that can trigger the autoimmune response, which in turn leads to the destruction of oxalate crystals and surrounding thyroid tissue.
In some cases, giant cell reactions were found around the crystals, suggesting an ongoing immune response.
A 2000 case report described four people with a rare genetic condition that led to oxalate buildup and the development of hypothyroidism. This report highlighted the role of oxalates in thyroid damage and thus hypothyroidism.
To complicate matters further, a 2006 study reported that a person developed excess oxalates due to hypothyroidism induced by amiodarone (one of the most toxic drugs for the thyroid)! Therefore, it is important to identify possible underlying oxalate issues.
Symptoms of oxalate formation or sensitivity
Oxalate formation or sensitivity should be suspected if you have any of the following symptoms (in addition to a thyroid disorder such as Hashimoto's or Graves.
- Joint Pain
- Pain in the body
- Burning while urinating
- Interstitial cystitis
- Burning during bowel movements
- Leaky gut
- Kidney stones
Factors that cause sensitivity
Sensitivity to oxalate can be caused by several factors that lead to the improper breakdown of oxalates in the body, such as a rare genetic disorder, problems affecting the small intestine such as small intestine bacterial overgrowth (SIBO) or growth of excessive fungus in the small intestine (SIFO)), other types of intestinal dysbiosis (which can result from past use of antibiotics), gastric surgery, Crohn's disease and short bowel syndrome.
People with low calcium intake (such as those on a dairy-free diet, which is otherwise beneficial for Hashimoto) may also have aggravated oxalate problems. This is because the calcium in our food can reduce our absorption of oxalates.
In some cases, oxalates can cause kidney stones. From a conventional medicine standpoint, if you are currently passing kidney stones, the stones can be tested by your doctor to see if they contain calcium oxalate. (If this test is positive, a low-oxalate diet should be followed to prevent more kidney stones from forming.
However, looking through the lens of functional medicine and root medicine (and whether you are currently passing kidney stones or not), doctors recommend a urine metabolite test. While some people recommend a low-oxalate diet trial to determine if oxalates are actually causing your symptoms, a low-oxalate diet can, in some cases, cause "oxalate dumping" (where too many oxalates try to leave your body at once). This can increase symptoms.
Hence, to strike a balance, it may be helpful to start by taking an inventory of your actual oxalate intake. The average diet contains 250 mg of oxalates per day, and eating a significant amount of it can lead to oxalate symptoms simply because you eat a lot more than you can break down.
That said, there may be more complicated genetic reasons for the poor breakdown, such as primary hyperoxaluria, and simpler ones, such as B6 deficiency or yeast overgrowth.
Foods with high oxalate content
The foods with the highest oxalate content per serving (around 50 mg/serving or higher) include:
- Dark leafy greens: spinach, kale, chard
- Root vegetables: white/sweet potatoes, parsnips, beets, rutabaga
- Other vegetables: carrots, celery, green peppers, Brussels sprouts
- Fruit: oranges, avocados, kiwis, tomatoes, raspberries
- Dried fruit: figs, dates
- Nuts/seeds: almonds, walnuts, cashews, pumpkin, tahini
- Grains: brown rice, buckwheat, wheat
- Beverages: carrot juice, tomato juice, rice milk
- Soy products
- Legumes: navy beans, fava beans, lentils, refried beans, red kidney beans
- Other: cocoa powder, stevia
Other foods commonly eaten on a paleo diet with oxalate levels above 50 mg per serving include baked potatoes, beets, cocoa powder, and okra. Raspberries come close at 48mg per serving! Certain foods are also extremely high in oxalate. However, we use them sparingly (like black pepper). These foods are usually not a big concern unless you use more than a teaspoon at a time.
Foods with moderate oxalate content
Foods with moderate levels of oxalates (i.e. ranging between those found in high and low oxalate foods) include:
- Fruits: apples, apricots, berries (except raspberries), peaches, grapefruit, plums
- Grains: white rice
- Nuts/seeds: sunflower seeds, pecans
Foods with low oxalate content
Foods with low oxalate levels (less than 50 mg/serving) include:
- Dairy: all dairy products (although dairy is not recommended for those with Hashimoto’s)
- Fruits: melons, mangoes, grapes, coconut
- Vegetables: broccoli, cauliflower, cabbage, lettuce, mushrooms, onions, red peppers, cucumbers
- Condiments: mustard, vinegar, mayonnaise
- Sweeteners: honey, maple syrup
- Beverages: herbal teas, apple juice, water, cider
Therefore, oxalates are particularly high substances in some foods. In excessive amounts, oxalates can build up, leading to inflammation and the progression of autoimmune diseases, such as Hashimoto's.
Symptoms of oxalate buildup or sensitivity can range from joint pain to depression or kidney stones. Because symptoms can be vague and overlap with other conditions, it is important to test for oxalate buildup and/or sensitivity. If there is a buildup, there are steps you can take to reduce it and improve your health!
These steps can include addressing gut health, reducing oxalate-rich foods in the diet, increasing water intake, and supplementing with B6, calcium, conjugated bile acids, and/or probiotics.
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