Do You Need A Low Oxalate Diet?
I have seen over and over again how one man’s superfood may be another person’s poison. Fruits, vegetables, nuts and even dark chocolate are without question staples of a healthy diet. But did you know that some of these highly nutritious foods might be poisoning your body and sending your defense mechanisms into chronic overdrive? Nature’s weapon of choice in this matter is a compound called oxalate.
Many people are just learning of the benefits of limiting oxalates in their diet and are finding relief from symptoms such as inflammatory conditions, autoimmune issues, mineral deficiency, and perhaps even autism. Although chances are you that you haven’t heard of oxalate until now, odds are greater that you may have a form of oxalate intolerance or know someone suffering from symptoms of excess oxalate.
Oxalate: What is That?
Oxalates are naturally occurring compounds in plants, animals and humans (1). The body is naturally able to synthesize oxalates from various compounds such as excess vitamin C, fructose as well as yeast. Vitamin B-6 deficiency, magnesium and thiamine deficiency are also ideal circumstances for increased oxalate synthesis. (18, 19, 20)
Unfortunately, oxalates are also found in high concentrations in some of the healthiest foods that we eat on a daily basis. When your body is faced with taking in excess oxalates found in foods, Popeye’s superfood can become our own body’s toxin.
Foods That Contain Oxalate
Dietary oxalate foods are excellent sources of key nutrients such as vitamin C, folate, and fiber and are obvious essentials to maintaining a healthy body. While you read the following list that provides examples of foods containing oxalate, think of what food alternatives have the nutrients that these sources provide. (1, 7)
Fruits: Highest concentrations include many citrus fruits such as lemon or grapefruit. Lower levels found in most berries, apples, plantains, watermelon and cantaloupe.
Vegetables: Very high oxalate concentration in beets, olives, rhubarb, spinach, turnip, yams. Other food sources with oxalates include mustard greens, most beans, artichokes. Little to no oxalate concentration found in broccoli, cabbage, cauliflower, cucumber, iceberg lettuce, mushrooms, zucchini and scallions.
Dairy: Most food sources contain little to no oxalates. Examples include eggs, cheeses, yogurt, and plain milk (chocolate is a source of oxalates so stray from the chocolate milk).
Grains: Concentration of oxalates measured in all grains such as whole wheat, oatmeal, brown rice, corn grits, couscous, soy flour and buckwheat. Little to no oxalates concentrated in flaxseed, barley malt flour, corn bran and oat bran.
Meat, Fish and Alternatives: Alternative protein sources such as veggie burgers, soy burgers and tofu burgers are very high in oxalates. Most meats such as buffalo, ham, hamburger, turkey and wild game contain low to no levels of oxalates. All fish except for tuna contain little or no oxalates.
Nuts and Seeds: All nuts are high in oxalate concentration and extremely high in almonds with concentrations more than quadrupled that of a single serving of mixed nuts. Flaxseed contains little to no oxalates.
Other: Oxalates are found in some processed snacks and beverages including potato chips and hot chocolate. Red and white wine contain little to no oxalates.
Testing For Oxalate Metabolism:
Clinically, I use the Great Plains laboratory organic acid test to determine if someone has elevated oxalates in their system. This is a simple urine test done in the comfort of your own home.
When I see elevated oxalic acid with elevated glyceric or glycolic acid it is usually a sign of a genetic hyperoxaluria. When oxalic acid is elevated without an elevation in glyceric or glycolic acid it is typically related to Candida Albicans overgrowth or a very high vitamin C intake.
This test also lets me analyze for vitamin B6 deficiencies and for Candida overgrowth which are both major causes of hyperoxaluria (10, 11, 12). From a functional nutrition and natural medicine perspective this test helps me to determine the cause and best diet and treatment for this condition.
Oxalate: What’s that Chalky taste?
Have you ever tasted spinach or swiss chard and it left a chalky and perhaps undesirable smooth texture on your tongue and along the roof of your mouth? This texture is a result of the oxalate content in the plant and acts as a defense mechanism so predators like you avoid consuming it.
It then makes sense then that the leaves of fruits and vegetables contain higher concentrations of oxalate compared to other anatomical parts such as the stem (1).
What are Oxalic Acid Salts?
Often referred to as oxalic acid, this organic acid is highly reactive with minerals including sodium, potassium, magnesium and calcium. Oxalate is like that friend who is great to bring to social gatherings and seems to make friends with everyone.
Just like some of the caustic relationships your friend might form, oxalic acid can combine with calcium and solidify in the kidneys and urinary tract creating a corrosive environment (3). Now for sure you have heard of kidney stones and urinary tract infections.
Excess Oxalate and Kidney Stones:
When oxalate concentrations are at exceedingly high concentrations in the body, calcium oxalate will develop into sharp crystals forming agonizing kidney stones. In fact, researchers have learned that 75% of kidney stones are actually derived from calcium oxalate. (3)
Some studies are cautious to blame dietary oxalate as the cause of kidney stones. Reasoning is because oxalate concentration in urine measured only accounts for 10-15% of total body concentration (1).
A better pathway of excreting oxalates through the body is through feces and higher concentrations in this form would represent less absorption of oxalates in the body. This route of excretion better ensures that oxalates will not bind to calcium and create health problems.
Oxalates and Cystic Fibrosis:
The condition caused from high oxalate concentration in urine is known as Hyperoxaluria (8). Think of “hyper” activity exhibited by your child, “oxal” derived from oxalate, and “uria” sounds like “urine”. Research found that 51% of cystic fibrosis patients had hyperoxaluria and this is a major risk factor for kidney stones (4).
Cystic fibrosis patients are often recommended to eat a low oxalate diet but the undermining mechanisms that cause the buildup of oxalate in their urine is not yet fully understood. One reason may be due to the reactivity of oxalate. Oxalate is 10 to 15 times stronger than calcium at combining to form oxalic acid salts which increases risk of kidney stones (2, 4).
Antibiotics Destroy Healthy Gut Flora:
Individuals suffering from cystic fibrosis undergo constant treatments to help clear their airways and reduce inflammation. Antibiotics are an important part of fighting against infections in these circumstances. Unfortunately, antibiotics may only create a different type of health disturbance.
Antibiotics destroy the helpful bacteria such as Oxalobacter formigenes in the intestines which are responsible for breaking down oxalate. The absence of these bacteria creates a domino of adverse health reactions such as fat malabsorption. (5, 14, 15)
Other healthy gut bacteria that are known to break down oxalates include lactobacillus acidophilus and bifidobacterium lactis (16). These are found in abundance in many fermented foods such as sauerkraut, kimchii, kefir, yogurt, etc and in high quality probiotic supplements.
Leaky Gut and Fat Malabsorption:
When the intestinal lining is damaged it increases the permeability of the inner layer and allows unwelcomed particles to cross the barrier between intestine and blood steam. Leaky gut increases your whole body’s immune response because of inflammation, nutrient deficiency, and oxidative stress.
If not corrected, over time your body will remain in a chronic inflammatory state and increased stress. Stress eats away at your B vitamin supply and as mentioned, vitamin B deficiency blocks reduces the bodies ability to adequately methylate and this aids in oxalate synthesis (2).
When the body has issues with digestion it can lead to fat malabsorption, where the intestines are no longer able to efficiently absorb nutrients in food. For this reason, cystic fibrosis patients also suffer from imbalances of sodium and calcium that may continue to aggravate gut inflammation and lead to kidney stones. (4, 5)
Thyroid Conditions and Oxalates:
When the body has more oxalate than it can breakdown, oxalate becomes stored over time in tissue and the thyroid. The human body is innately a design of intelligence. If it is being provided something in excess that it doesn’t need, it will simply store it away for future use just like a squirrel hoards acorns for the cold winter months.
Oxalate binds to a hormone released by the thyroid, T3. Responsibilities of T3 include sending signals to regulate body temperature, metabolism and heart rate. However, excess oxalate binds to T3 creating crystals in the thyroid and consuming the attention of this hormone. Unable to perform other functions, conditions with thyroid disturbances have been linked to excess oxalate. (2)
Autism and Oxalates:
Researchers have suggested that individuals with autism may be predisposed to oxalate intolerance. Although the metabolic pathways are unclear, individuals with autistic tendencies have seen an improvement in their symptoms when consuming a low oxalate diet (2).
The first study analyzing oxalate in autistic children was only recently released in 2012. Findings suggest that the development of autistic symptoms may be from excessive intestinal absorption and increased oxalate absorption through the kidneys as others oxalate studies have noted.
Oxalate Elimination Diet
An individual with a healthy gut and otherwise healthy immune system can generally tolerate low levels of oxalate from foods. Individuals with either common or rare conditions associated with excess oxalate concentrations in the body may benefit from eliminating dietary sources of oxalate.
Researchers suggest that you do not need to completely eradicate every source of oxalate foods from your diet as much as you should limit the consumption to less than 50 mg daily. Keep in mind that ¼ cup of raw spinach contains this dietary dose. (1)
I have found that reducing oxalate levels by 20% compared to the former diet is the best place to start and often with the addition of key supplements such as potassium citrate, vitamin B6, magnesium and activated charcoal, this slight reduction in oxalates in the diet is all that is needed.
I teach my clients to minimize their consumption of spinach, beets, grains, nuts, sweet potatoes and chocolate for 3 months until we retest and see that their oxalate levels are in the normal range. From there, they can have a serving of these 1x per week, while we continue with the supplement protocol and retest again in 3 months to see if we were able to keep oxalate levels under control.
Symptoms of Oxalate Intolerance:
- Inflammation in joints causing muscle stiffness and pain
- Kidney stones
- Urinary tract irritation, pain or urgency to urinate
- Vulvar pain (chronic irritation and pain of the female genitalia)
- Abdominal problems such as constipation or diarrhea
- Vitamin or mineral deficiency such as magnesium or vitamin B
- Lethargy or problems sleeping
- Histamine reactions such as hives
Associated with Oxalate Intolerance:
- Vulvar pain syndrome
- Cystic fibrosis
- Chronic obstructive pulmonary disease (COPD) or asthma
- Chronic kidney stones (medically termed nephrolithiasis)
- Thyroid disease or problems such as lupus, cirrhosis, or Wilson’s Syndrome
- Connective tissue disease
- Autoimmune issues
- Irritable bowel syndrome
Improve Oxalate Related Health Concerns
Man’s diet today has become so far removed from nature that oxalate intolerance is just another health concern to add to the list of medical problems. Here are a few tips to start you on your health journey:
1. Avoid Nuts & Grains: Avoid nut flours and opt for coconut flour for optimal oxalate free and grain free nutrition.
2. Avoid Anti-Biotics if Possible: Use antibiotics only in an emergency situation and never for general health.
3. Rotate Your Produce: Rotate the produce that you eat. Iceberg lettuce varieties contain little to no oxalate and can add bulk to your salad in combination with spinach and kale.
4. Cook But Don’t Overcook Your Veggies: Blanching, boiling, and sautéing vegetables will reduce oxalate content but if you cook them too long it only reduces the valuable nutrient supply available. Studies have shown that a maximum reduction of only 15% oxalate concentration occurs through cooking (1).
5. Improve Gut Health: Supplement your diet with probiotic foods and supplements to replenish beneficial bacteria that break down oxalate. Examples of fermented foods are yogurt, kefir, cultured vegetables, kombucha, and sauerkraut. A high quality 100 billion CFU probiotic supplement with lactobacillus acidophilus and bifidobacterium lactis should be used as well.
7. Optimize Vitamin D Levels: Optimize your vitamin D levels by getting regular sun exposure or supplementing daily.
8. Don’t Take High Dose Vitamin C: Avoid taking more than 2,000 mg of vitamin C daily (6). Remember, vitamin C can be used to make oxalate.
9. Increase Your Citrate Consumption: Citrate or citric acid will bind to oxalates and help the body to remove them. You find citrates in citrus fruits such as lemons and limes. I also recommend taking a potassium citrate capsule with each meal to help the body bind the oxalates in that meal.
10. Use Activated Charcoal: Activated charcoal is a binding agent that will help to reduce oxalate levels in the gut and reduce yeast and bad bacteria that disrupt normal oxalate metabolism. I recommend potassium citrate with meals and activated charcoal outside of meals.
12. Hydrate: Be sure to drink plenty of water to dilute the oxalate concentration in the kidneys
Supplements For High Oxalate Levels:
The main supplements I use for elevated oxalate levels include potassium citrate, vitamin B6 and activated charcoal support to help the body to deactivate, bind and eliminate oxalates effectively. The form of B6 that works best with this is the activated form called pyridoxal-5-phosphate (P5P).
These supplements are relatively low cost and make a big difference. It would also be a good idea to include vitamin D, B vitamins, magnesium and omega 3 fatty acids while going through this oxalate protocol. The strategy I use, along with a low oxalate diet includes the following.
Potassium Citrate: Take Thorne Potassium Citrate, Take 1 capsule with each meal
Vitamin B6: Take 1 capsule of Thorne P5P, 2 times daily (with or without meals)
Activated Charcoal: Use Bulletproof coconut charcoal, Take 2-4 capsules away from meals (about 90 mins after meals) – 2 times daily.
Do this for 90 days and then retest using the OAT Test to see what the oxalate levels look like. If the test results look good (which they do 90% of the time), than you can begin adding back the healthy oxalate foods we reduced. This would include sweet potatoes, nuts, raw cacao, beets and spinach and continue on this protocol.
If you notice symptoms returning, try reducing oxalates a small amount and see if that reduces the symptoms. You can also retest with the OAT test. As the microbiome improves, the body will be able to manage the oxalate levels and you will be able to enjoy some of the high oxalate foods from time to time.
Sources For This Article Include:
- The world’s healthiest foods: Can you tell me what oxalates are and in which foods they can be found? Link Here
- Low Oxalate Diet: What Is Oxalate? Link Here
- The VP Foundation: The Truth About Oxalate Link Here
- Kianifar HR, et al. Predisposing Factors for Nephrolithiasis and Nephrocalcinosis in Cystic Fibrosis. Iranian Journal of Pediatrics. 2011 Mar;21(1):65-71. PMCID: 3446121
- Hoppe B, et al. Absorptive Hyperoxaluria Leads to an Increased Risk for Urolithiasis or Nephrocalcinosis in Cystic Fibrosis. American Journal of Kidney Diseases. 2005 Jul; 46(3):440 – 445.
- UPMC: Low Oxalate Diet Link Here
- Harvard T. H. Chan School of Public Health Nutrition Department’s File Download Site Link Here
- UW Health: Oxalate Link Here
- Konstantynowicz J, et al. A potential pathogenic role of oxalate in autism. Eur J Paediatr Neurol. 2012 Sep:16(5):485-91. PMID: 21911305
- Effects of Hydroxyproline and Vitamin B-6 on Oxalate Synthesis in Rats Link Here
- Loewus FA, Saito K, Suto RK, Maring E. Conversion of D-arabinose to D-erythroascorbic acid and oxalic acid in Sclerotinia sclerotiorum. Biochem Biophys Res Commun. 1995 Jul 6;212(1):196-203. PMID: 7612007
- Muntz FH. Oxalate-producing pulmonary aspergillosis in an alpaca. Vet Pathol. 1999 Nov;36(6):631-2. PMID: 10568451
- Gambaro G, Bordoni A, Hrelia S, Bordin L, Biagi P, Semplicini A, Clari G, Manzato E, Baggio B. Dietary manipulation of delta-6-desaturase modifies phospholipid arachidonic acid levels and the urinary excretion of calcium and oxalate in the rat: insight in calcium lithogenesis. J Lab Clin Med. 2000 Jan;135(1):89-95. PMID: 10638699
- Kumar R, Mukherjee M, Bhandari M, Kumar A, Sidhu H, Mittal RD. Role of Oxalobacter formigenes in calcium oxalate stone disease: a study from North India. Eur Urol. 2002 Mar;41(3):318-22. PMID: 12180235
- Sangaletti O, Petrillo M, Bianchi Porro G. Urinary oxalate recovery after oral oxalic load: an alternative method to the quantitative determination of stool fat for the diagnosis of lipid malabsorption. J Int Med Res. 1989 Nov-Dec;17(6):526-31. PMID: 2628129
- Azcarate-Peril MA, Bruno-Bárcena JM, Hassan HM, Klaenhammer TR. Transcriptional and functional analysis of oxalyl-coenzyme A (CoA) decarboxylase and formyl-CoA transferase genes from Lactobacillus acidophilus. Appl Environ Microbiol. 2006 Mar;72(3):1891-9. PMID: 16517636
- Chetyrkin SV, Kim D, Belmont JM, Scheinman JI, Hudson BG, Voziyan PA. Pyridoxamine lowers kidney crystals in experimental hyperoxaluria: a potential therapy for primary hyperoxaluria. Kidney Int. 2005 Jan;67(1):53-60. PMID: 15610227
- Effects of Sugars and Vitamin B-6 Deficiency on Oxalate Synthesis in Rats Link Here
- Rushton HG, Spector M. Effects of magnesium deficiency on intratubular calcium oxalate formation and crystalluria in hyperoxaluric rats. J Urol. 1982 Mar;127(3):598-604. PMID: 7062446
- Sidhu H, Gupta R, Thind SK, Nath R. Oxalate metabolism in thiamine-deficient rats. Ann Nutr Metab. 1987;31(6):354-61. PMID: 3426152