Mold and Oxalates: The Surprising Link That Could Be Affecting Your Health

In my functional medicine telehealth practice, I work with patients who have mold illness almost every day.

The thing about mold illness, like so many of our chronic health concerns, is that it often takes a long time to be detected, and it rarely exists alone.

Symptoms of mold exposure, including fatigue, brain fog, headaches, and digestive issues, can mirror the symptoms of other health conditions.

And not everybody who is exposed to mold experiences symptoms – there are often other underlying issues that either make a person more sensitive to mold, exacerbate the problem, or both.

My job as a clinician is to make these connections and uncover these hidden causes and triggers.

One connection I wish more practitioners were making? The link between mold and oxalates.

In this article, I’m going to break down what you need to know about oxalates, the connection to mold, how to find out if you’re sensitive to mold, oxalates, or both and why, and what to do next.

Let’s get into it.

What are Oxalates?

Oxalates are compounds found in several different kinds of plants, including certain fruits, vegetables, and legumes. Plants use oxalates for protection against viruses and bacteria, and to deter animals and insects.

When we eat oxalate-containing plants, we’re also consuming oxalates. Most of us expel the majority of the oxalates we consume through our urine and stool, so we don’t really need to worry about them.

However, some people may have an impaired ability to expel oxalates, or may experience a buildup or overload of oxalates.

This is a problem because if not eliminated, oxalates bind to minerals including magnesium, calcium, and iron in the body, blocking their absorption. (1, 2) Once they’ve bound to minerals, they also create oxalic acids, which can lead to or contribute to various health concerns.

The Mold and Oxalate Connection

Mold and oxalates are connected in several ways.

First, in addition to those found in plants, certain kinds of molds (including Aspergillus), fungi, and yeasts (including candida) can also produce oxalates. Especially if you’re already dealing with a buildup or a sensitivity, this may be contributing to your overall load.

The biggest issue with mold and oxalates is that they both make it harder for the body to deal with the other.

When oxalates build up in the body, they can impair immune system function and disrupt gut health, making us more susceptible to harm from mycotoxins (toxins created by certain kinds of mold) and to yeast overgrowth.

Then, yeast and mold, as mentioned above, can produce more oxalates, creating a vicious cycle.

Similarly, if you’re dealing with mold illness or mold sensitivity, your body’s natural detoxification system is already in overdrive, making it harder to clear oxalates. Candida also feeds on oxalates, as may certain fungal species.

Both mold toxins and oxalates (particularly for those who are sensitive to them or who have existing imbalances or health conditions) can also trigger inflammation, immune system dysfunction, and gut issues.

All of this is important to understand if you’re dealing with mold sensitivity OR oxalate sensitivity (or if you suspect you’re dealing with one or both of these). Why? Because it helps us untangle the root cause and triggers of your illness.

Signs of Mold Sensitivity vs. Oxalate Sensitivity

The signs of mold sensitivity and oxalate sensitivity (or oxalate buildup) may overlap – and some people may be experiencing both. A functional medicine practitioner can help you understand your symptom patterns and identify the likely triggers of your symptoms (and what to do next).

Here are a few signs and symptoms of both.

Symptoms of oxalate intolerance, sensitivity, or overload may include: 

• Joint and/or muscle pain
• Fatigue
• Muscle twitching
• Mineral deficiencies even when eating a healthy diet
• Digestive issues including nausea or diarrhea; IBS
• Frequent headaches
• Burning sensation in the eyes, ears, mouth, or throat
• Brain fog; difficulty focusing
• Brittle bones
• Irregular heartbeat
• Kidney stones
• Fibromyalgia

Symptoms of mold sensitivity or illness may include: 

• Fatigue
• Weakness
• Brain fog; difficulty concentrating
• Digestive concerns including nausea, abdominal pain, and/or diarrhea
• Dizziness or vertigo
• Skin issues including rashes or itchiness
• Chronic headaches
• Respiratory issues including coughing, wheezing, shortness of breath, or sinus congestion
• Anxiety
• Depression, low mood, or mood swings

How to Find Out If You’re Oxalate Sensitive

With so many different factors that may contribute to symptoms like fatigue, headaches, brain fog, and joint pain, how do you know if excess oxalate levels are behind yours?

I would definitely recommend working with a knowledgeable functional medicine practitioner who can take a closer look at your symptoms, risk factors, and health history.

There are some specialized testing options, like an organic acid test (OAT), that look at markers of high oxalates as well as things like gut microbiome health, nutritional deficiencies, genetic markers that may predispose someone to oxalate issues or mold sensitivity, signs of mold illness, heavy metals, and more.

A low oxalate diet trial can also help you to determine whether oxalates are causing problems for you.

However, unlike many other elimination diets, moving straight into a very low oxalate diet can actually trigger a worsening of symptoms for those who do have a buildup (this is called oxalate dumping and is similar to a die-off reaction). This is another reason why working with a practitioner who can guide you through the process step-by-step may be helpful.

LISTEN: Rachel Brathen: Why She Quit Being A Vegan + How She Healed From Mold Toxins 

Oxalate Intolerance Risk Factors

There are a few conditions and factors that may make you more likely to experience an oxalate sensitivity, intolerance, or buildup.

• Gut health issues. This is one of the biggest risk factors for oxalate intolerance. Inflammation, leaky gut, an imbalanced gut microbiome (dysbiosis), SIBO, and other digestive issues can increase the likelihood of oxalate buildup and impaired nutrient absorption.
• Chronic or recent antibiotic use. Antibiotics are known to disrupt the gut microbiome, and can kill off certain kinds of bacteria that we rely on in order to degrade oxalates. In particular, antibiotics may kill a bacterial species called Oxalobacter formigenes, which plays a significant role in reducing the buildup of oxalates in the body.
• History of kidney problems or kidney stones. The majority of kidney stones are actually made up of oxalates. Those with a history of kidney stones or related kidney issues should likely avoid a high intake of dietary oxalates. (3)
• Low vitamin B6 or thiamine (vitamin B1) levels. Low levels of B6 and/or B1, as well as magnesium, can make it harder for the body to eliminate oxalates.
• Genetic factors. Certain gene variations may predispose some people to oxalate sensitivity. Keep in mind that these variations don’t guarantee that a person will have a problem with oxalates – our health outcomes are an interaction between our genes and our environment.
• Mast cell activation syndrome (MCAS) or histamine intolerance. Oxalate intolerance often overlaps with histamine intolerance and/or mast cell issues. If you already know you’re dealing with histamine overload, but there seems to be more going on, oxalate buildup may also be worth looking into.

High Oxalate Food List

Here is a list of some of the most common foods that are high in oxalates. As you’ll see, most of these are generally healthy and packed with nutrients – remember, they’re all plant foods!

• Raw green leafy vegetables including spinach, kale, broccoli, kale, and swiss chard
• Beets
• Potatoes
• Beans
• Radishes
• Black pepper
• Nuts including almonds, peanuts, and cashews
• Soy products
• Berries
• Chocolate and cocoa powder
• Buckwheat
• Kiwi
• Sweet potatoes
• Leeks

Not everyone should avoid high oxalate foods, and for those who are dealing with oxalate overload, ideally it’s only short term and these healthy foods can be reintroduced into your diet once the underlying issue has been resolved.

Again, it’s not generally recommended to eliminate all high oxalate foods at once, as this sudden elimination can be hard on the body and cause a worsening of symptoms.