Chronic Fatigue Syndrome (CFS) is a complex and often misunderstood condition that leaves many people struggling with persistent exhaustion, brain fog, and muscle aches.
Although there are multiple different factors that contribute to symptoms and every case is different, diet can sometimes play a significant role in symptom management.
There are many different dietary approaches and different things will work for different people depending on the mechanisms contributing to their specific case. One dietary component that has gained attention in this context is oxalates—naturally occurring compounds found in many healthy foods such as spinach, nuts, and berries. For some individuals with chronic fatigue, higher oxalate intake may contribute to symptom burden.
In this blog, we’ll explore the relationship between oxalates and chronic fatigue, possible causes of oxalate intolerance and how adjusting oxalate intake might help alleviate some of the challenging symptoms of this condition.
What Are Oxalates?
Oxalates are naturally occurring compounds found in many plant-based foods, such as spinach, rhubarb, and certain nuts and seeds. Chemically, they are salts or esters of oxalic acid.
In the body, oxalates can bind with minerals such as calcium, magnesium, potassium, zinc, and iron to form compounds like calcium oxalate, which is most commonly discussed in relation to kidney stones.
In certain contexts, oxalates can form crystals, which may be irritating to tissues in more sensitive individuals. There is also some emerging discussion around whether oxalate accumulation may interact with tissues and cellular processes, although this area is still being explored.
In excess, oxalates may contribute to inflammatory processes in some individuals.
It’s important to emphasise that many people consume oxalate-containing foods without any issues. However, some individuals may have a lower tolerance — sometimes referred to as “oxalate sensitivity” or “oxalate intolerance” — where the overall load becomes more difficult for the body to manage.
Could Oxalates Be Contributing To Your Symptoms?
In clinical practice and emerging research, oxalates have been explored as one potential contributing factor in a range of symptoms.
It’s important to emphasise that these symptoms are not caused solely by oxalates, and in many cases there are multiple overlapping drivers — including gut health, immune function, nervous system regulation, and overall biochemical balance.
However, in certain individuals, oxalate load may be one piece of a much broader picture.
Some of the patterns where oxalates are sometimes considered include:
Neurological & Cognitive
- Brain fog
- Headaches or migraines
- Dizziness or vertigo
- Neurological-type symptoms (e.g. tingling, sensitivity)
Musculoskeletal & Pain
- Joint pain
- Muscle aches
- Back pain
- Fibromyalgia-type symptoms
Inflammatory & Immune
- Chronic inflammation
- Mast cell activation symptoms
- Autoimmune patterns
- Asthma or airway sensitivity
Hormonal & Energy
- Fatigue
- Thyroid imbalances
- Polycystic Ovary Syndrome (PCOS)
Digestive Health
- IBS (Irritable Bowel Syndrome)
- Bloating or digestive discomfort
- Increased gut sensitivity
Urinary & Kidney
- Kidney stones
- Urinary discomfort (e.g. interstitial cystitis-type symptoms)
- Recurrent UTI patterns
Nutrient & Mineral Balance
- Electrolyte imbalances
- Mineral deficiencies
Important:
This is not intended as a diagnostic tool, but rather a way to highlight patterns that may be worth exploring in the right context.
In practice, oxalates are rarely the sole driver of symptoms — but in some cases, reducing the overall load may help create more capacity for the system to stabilise.
How Do You Know If Oxalates Are A Problem For You?
There is currently no single reliable way to definitively assess this, so we often look at a combination of factors. This might include considering your symptom patterns, your dietary intake, and, where appropriate, functional testing.
In clinical practice, we sometimes see individuals with patterns such as thyroid imbalances, persistent fatigue, or chronic aches and pains where oxalates may be one piece of the puzzle, although never the only consideration.
In some cases, testing may offer additional context. Organic acids testing (OAT), such as the OAT by Mosaic Diagnostics or Organix by Genova Diagnostics, includes markers like glycolic acid, glyceric acid, and oxalic acid.
Elevated markers may suggest increased oxalate excretion, although interpretation should always be made in context. A lower oxalate approach may be worth exploring in some cases, but it isn’t always necessary.
It’s also worth noting that oxalate clearance can fluctuate. This means that even if oxalate markers appear within range on a test, it does not always fully rule out their relevance.
In some situations, a timed urine collection (such as a 6-hour sample) may provide additional insight.
Ultimately, one of the most practical ways to explore whether oxalates are relevant is through gentle, gradual dietary adjustments, while observing how your body responds over time.
How Do You Address Oxalates?
To address oxalates we want to address possible triggers (such as mould), slow the input from dietary oxalates, slowly and support degradation and elimination.
Common Oxalate Triggers
Dysbiosis (Imbalance of Gut Bacteria): A disruption in the balance of gut bacteria can lead to higher oxalate absorption. Certain bacteria in the gut, like Oxalobacter formigenes, help break down oxalates. When these beneficial bacteria are low or out of balance, oxalates are less efficiently broken down and can accumulate in the body. We can test for Oxalobacter formigenes using a stool test such as the GI Effects by Genova Diagnostics. Additionally low levels of species such as B.animalis and L.animalis have also been implicated. These can be measured on a gut zoomer test.
Leaky Gut Syndrome: Increased intestinal permeability (leaky gut) can lead to more oxalates being absorbed into the bloodstream, which may increase the burden on the kidneys and other organs.
Candida Overgrowth: Candida may contribute to higher oxalate production in the gut. In some cases, Candida may produce oxalates as a byproduct of its metabolism. This is particularly relevant in individuals with a compromised gut microbiome or leaky gut, where oxalates can be absorbed into the bloodstream rather than being broken down properly.
Mold: Inflammation from mold producing mycotoxins can lead to increased oxalate production and poor oxalate metabolism, increasing the overall oxalate burden on the body.
High Oxalate Diet: A diet which is high in oxalates may contribute to oxalate intolerance, especially when compounded by bacteria or fungal overgrowth, leaky gut and nutritional deficiencies. In her Book “Toxic Superfoods”, Sally K Norton describes a diet which has over 600mg of oxalates per day as extremely high. However, even lower levels of oxalates may still be problematic based on factors previously discussed.
High Intake of Vitamin C: Vitamin C (ascorbic acid) can convert into oxalate in the body. While vitamin C is essential for health, excessive amounts, especially from supplements, can lead to an increase in oxalate production. High doses of vitamin C may contribute to the formation of kidney stones in susceptible individuals.
Mitochondria Dysfunction: Mitochondrial dysfunction, which can occur in certain diseases or conditions, may lead to an overproduction of oxalates. This is because the mitochondria are involved in various metabolic pathways, including the breakdown of oxalates.
Nutrient Deficiencies and Oxalates
Oxalate intolerance can both exacerbate and create nutrient deficiencies. Some of the important nutrients to consider are calcium and electrolytes such as magnesium, potassium and sodium.
Calcium Deficiency: Calcium binds with oxalates to form calcium oxalate, which is usually excreted in the urine. If calcium intake is low, the body may absorb more oxalates, leading to higher levels.
Vitamin K Deficiency: Vitamin K is involved in calcium metabolism and helps to direct calcium into bone. If vitamin K is deficient, this can cause increased binding of dietary and/or supplemental calcium to oxalates and increase risk of kidney stones.
Magnesium Deficiency: Magnesium also helps to prevent oxalate buildup. A lack of magnesium can exacerbate the effects of high oxalate consumption.
Vitamin B6 Deficiency: Vitamin B6 plays a crucial role in oxalate metabolism. Low levels of B6 can impair the body’s ability to process oxalates, leading to increased oxalate production.
Digestive Support
Oxalates are typically associated with digestive imbalances and therefore supporting the gut will be part of the process. There is no supplement at the moment which contains the beneficial strains of Oxalobacter Formigenes, L.animalis and B.animalis but spore based probiotics may be beneficial.
Additionally we may want to address digestive and absorption, especially of fat which can fuel bacterial overgrowth, add support for the gut mucosal lining and address dysbiosis and mold and yeast overgrowth. This needs to be done in a case specific manner depending on individual needs. The challenge can be that many antimicrobial herbs are high in oxalates so sometimes we have to reduce the oxalate load through diet before herbs can be tolerated.
How To Reduce Dietary Oxalates
Often well meaning health conscious people unintentionally switch to a high oxalate diet in an attempt to improve their health. They eat dark chocolate to reduce their sugar intake, give up cows dairy and start consuming almond milk, they have spinach smoothies and turmeric and ginger shots. All of which are high oxalate foods and when you add the content of these foods up, you may be consuming several 100mg of oxalates per day.
If you are someone who has always believed that an abundance of vegetables is good for you and if you are like me, a lover of green tea, dark chocolate and salad. Following a low oxalate diet can sometimes invite a shift in how we think about “healthy eating,” particularly when individual tolerance differs
For someone experiencing oxalate overload a therapeutic diet may be around 60mg of oxalates per day or less. However, dietary oxalates need to be reduced slowly and sometimes a lighter load, without high levels of restriction, can be therapeutic.
When lowering the dietary oxalate load, this may encourage the system to excrete more stored oxalates, which can cause damage and flare symptoms as part of the process. This is often referred to as “oxalate dumping”, although the mechanisms are still being explored and experiences can vary widely.
Symptoms of oxalate dumping may include:
- Increased hunger
- Headaches
- Nausea
- Fatigue
- Brain Fog
- Musculoskeletal pain
- Flank pain (above the kidneys)
- Rectal pain
- Eye pain and pressure
- Rash
- Vulvar pain in women
- Kidney stones
In certain individuals — particularly those with a history of kidney stones or complex health conditions — it’s important that any dietary changes are approached cautiously and ideally with support.
The approach that I use with clients when addressing oxalates is to ask them to record their baseline intake. There are various apps and resources available online that will inform you of the oxalate content of certain foods. Sally K Norton’s website has some great resources. Note that there are no exact standards for the amount of oxalates in food. Multiple different factors can influence the amount of oxalates in food and therefore we only have a rough guide.
Once a baseline of intake has been established I recommend a 5-10% reduction each week based on the individual, their sensitivity and overall stability. For sensitive individuals, even a very slow reduction could still cause dumping and therefore it is important that you do not rush.
If you experience any flares you can slow the process down by increasing your oxalate intake again by a small amount or doing a slightly lower oxalate day followed by a slightly higher oxalate day. Other suggestions might be:
- Make adjustments every 2 weeks instead of weekly
- Please also drink plenty of water
- Baking soda mixed with water 30 minutes before meals may also help with dumping symptoms – this may suppress stomach acid so only to be used when needed
- Sauna or hot/cold contrast can also be supportive if tolerated
In some cases it can also be supportive to reduce the dietary histamine load as oxalate clearance can activate mast cells and cause an increase in histamine levels, which can exacerbate symptoms.
Food Swaps
In the initial stages of change it can be helpful to swap one food for a lower oxalate food to avoid too much limitation to your diet. The table below is not an exhaustive list but it gives some examples:
| High Oxalate Foods | Lower Oxalate Swaps |
| Spinach | Lettuce |
| Nuts | Pumpkin seeds, pistachios, macadamia nuts, flaxseeds |
| Almond Milk | Coconut Milk, Oat Milk, Cow’s Dairy |
| Raspberries and Strawberries | Blueberries, Honeydew Melon |
| Sweet Potato, Beetroot | Butternut Squash |
| Brown Rice | White Rice |
| Cucumber with skin on | Cucumber with skin off |
| Dark Chocolate | White Chocolate or Vanilla Ice Cream |
Often I will suggest to clients that each week they make one swap and this will support gradually lowering the oxalate load over time.
Supplements and Degradation
When addressing oxalate overload it is important to be mindful of supplements. Many supplements which are often considered supportive for inflammation (curcumin for example) may be high in oxalates.
A less is more approach can be helpful but there are some supplements that may be beneficial. These include:
- Calcium; due to its ability to bind oxalates which helps them clear in the urine.
- Electrolytes such as sodium, potassium and magnesium. These can be taken in various forms such as epsom salt (magnesium sulphate) baths, adding salt to food and oral supplemental forms.
- Sulphur: Oxalate and sulphate share transporters which means that oxalate moves through the body on sulphate transporters and binds to sulphate receptor sites. This means that one will influence and by increasing sulphate and sulphate metabolism we may influence how oxalates are processed in the body. Magnesium sulphate is a great way to get both magnesium and sulphur plus so extra self care!
- Citric Acid: Citric acid is naturally occurring in certain fruits such as citrus fruits and berries and can also be taken in a chelated supplement e.g. potassium citrate, calcium citrate or magnesium citrate. Citrates are often used in clinical settings to support oxalate balance, particularly in relation to kidney stone risk. Citric acid isn’t always tolerated by those who are histamine sensitive, therefore, proceed with caution.
- Vitamin B6: Vitamin B6 plays a crucial role in oxalate metabolism and therefore vitamin B6 can be supplemented as either part of a B-complex or on its own, depending on tolerance.
How Long Do You Follow The Diet For?
Following a low oxalate diet is a long term commitment and it is not for the faint hearted. It can take months and in some cases even years to lower one’s oxalate load. Consistency is often helpful, although the approach should always be adapted to the individual.
Oxalates can clear in fits and starts. It is not uncommon for people to feel quite well as soon as they reduce their oxalates, only to experience a flare several weeks later. As the body starts to function better, it may begin to clear more. This can sometimes look like going backwards and it can be hard to stick to the diet when you feel it isn’t working.
Although we do not want to encourage aggressive oxalate dumping, these fluctuations can sometimes be part of the process, although they should always be monitored and supported appropriately. As time goes on things may get easier.
From personal experience I can share that it is important to make space in your life for the process as the ups and downs can be wearing physically and emotionally if we are expecting to just change our diet and get on with things as normal.
As time goes on and you feel more well and more stable, you may be able to reintroduce some higher oxalate foods back into your diet with around 150mg per day being a good maintenance dose for those with good digestive health.
If underlying triggers such as dysbiosis, SIBO, Candida, Mold or leaky gut are not addressed, oxalate tolerance may continue to be low.
Help and Support
It’s important to remember that oxalates are just one potential piece of a much larger picture. For some people, they may be relevant. For others, they may not be a significant factor at all. The goal is not restriction for the sake of it, but understanding your individual physiology and responding accordingly.
If you feel curious as to whether any of the concepts mentioned here could be implicated in your own health journey, consider working with us. Find more about your options here.
