If you’re at risk for kidney stones or kidney disease, you’ve likely heard that a low oxalate diet could help curb these risks.
But did you know that the influence of oxalates in your diet may go far beyond kidney issues?
These highly reactive molecules may play a major part in the development of chronic disease, like autoimmune reactions and disruptions of the digestive system.
Since many high oxalate foods seem to be part of an otherwise “healthy” diet, their significance may go unnoticed. If you struggle with issues like autoimmune disease, poor digestion, and even persistent neurological trouble, it may be time to see if eliminating these plant foods reduces your symptoms.
Let’s take a look at the definition of oxalates, benefits of reducing your intake, and how to eat a diet low in oxalates.
What are oxalates?
Oxalate (or oxalic acid) is a compound found in a variety of plant-based foods. Under a microscope, oxalates are jagged in structure and look somewhat crystalline.
During metabolism, oxalic acid combines with other minerals like calcium, sodium, magnesium, and potassium to form compounds like calcium oxalate and sodium oxalate in the kidneys. In a healthy person, around 90% of the oxalate consumed will be excreted through a combination of stool and urine.
You consume oxalates in many foods high in nutrients like vitamin C, but your body also creates oxalates as it breaks down vitamin C molecules. (1) Another source of oxalates can come from molds and yeast, such as Aspergillus and Candida.
5 Benefits of a Low Oxalate Diet
1. Decreased Risk of Kidney Stones
Why is oxalate, out of all molecules, a major factor of kidney stones? Calcium oxalate stones are the most common type of kidney stones. Calcium stones account for 80% of cases, followed by 20% calcium phosphate. (2)
Because of the chance of recurrence in stone formers, many doctors will specifically recommend a low oxalate diet to reduce the chance of another kidney stone.
It’s important to note, however, that not all sources show that reducing dietary oxalates is the best solution for kidney stones. (3) A 2014 review of kidney stones as related to calcium intake noted that eating high calcium foods may actually reduce kidney stones more effectively than a low oxalate diet. (4)
Other ways to reduce kidney stone risk include the recommendations to drink plenty of water, cut sodium intake, and eat less protein. (2)
2. Improved Mineral Absorption
Because so much oxalate in your diet binds to important minerals, a high- or moderate-oxalate diet may reduce the amount of those minerals you absorb and use. One small human trial noted that participants’ levels of magnesium, calcium, and zinc all dropped significantly when they consumed high oxalate foods for just one week. (5)
By filling your diet with primarily low-oxalate foods, you may improve mineral absorption within the gut.
3. Reduced Risk of Autism in Children
A major focus of debate surrounding the benefits of a low oxalate diet has to do with autism after a 2012 study conducted in Poland. Scientists found that high oxalate levels may play a part in the development of this disease. (6)
The possible reasons for this are threefold. First, children with autism are known to have “impaired renal excretion,” meaning their kidneys aren’t as efficient as a neurotypical child’s at getting rid of toxins. (7)
Second, gut dysbiosis and autism are very clearly linked in the scientific literature, which suggests oxalate compounds may be able to escape the intestines in the presence of leaky gut. As these compounds cross the blood-brain barrier, oxalates may, in turn, contribute to behavioral and neurological issues in autism. (6)
Lastly, because those with autism suffer from an overall less diverse gut microbiome, their ability to metabolize oxalates is impaired. A specific type of good bacteria in the gut, Oxalobacter formigenes, is needed for this process. If O. formigenes isn’t present in large enough quantities, oxalates can’t be broken down and excreted. (8)
4. Less Symptoms of Vulvodynia
A condition that involves pain of the vulva, vulvodynia has been associated with oxalates for many years. Although it seems oxalates don’t actually trigger vulvodynia, eating a low oxalate diet does seem to alleviate the pain of this condition. (9, 10)
5. Improvement of Autoimmune Symptoms
The gut is a complex and delicate environment. When the good-to-bad bacteria ratio is out of balance in the gut, many issues arise — one of which is symptoms of autoimmune disease. Like many functional practitioners, I believe autoimmune disease isn’t so much an issue of the immune system attacking itself, but a sign of major gut dysbiosis.
Oxalates in the diet reduce the minerals you absorb and take up valuable bodily detoxification resources. This may contribute to dysbiosis, especially for those at an increased risk of hyperoxaluria (high urinary oxalate excretion).
Can you benefit from a low-oxalate diet?
For many individuals, high oxalate foods are little cause for concern. However, some people are at a higher risk of symptoms caused by a large intake of dietary oxalates. These include:
- Those who have recently and/or often used antibiotics (8)
- Children with autism (6)
- People with a family history of kidney disease and/or kidney stones
- Patients who have undergone surgery that impacts the gut (gastric bypass, removal of bowel, etc.)
- Anyone with low mineral absorption
- Patients with a history of autoimmune conditions
How to do a Low Oxalate Diet
On a standard low oxalate diet, you’ll want to keep your intake between 40-50 milligrams of oxalate maximum each day. Consume only a small amount of food high in vitamin C and avoid taking more than 500 milligrams of vitamin C daily.
That’s a great start, but eliminating oxalate fruits is not the whole story.
High Oxalate Foods to Avoid
These foods should be eaten in strict moderation while reducing oxalate intake: (note, there are no meats on this list)
- Fruits
- Orange peel
- Lime peel
- Lemon peel
- Blueberries
- Blackberries
- Raspberries, red and black
- Kiwi
- Rhubarb
- Figs, dried
- Vegetables
- Spinach
- Sweet potatoes
- Beetroot and beet greens
- Peppers, green
- Swiss chard
- Celery
- Kale
- Okra
- Legumes, Nuts, and SeedsGrains and starches
- Nuts
- Peanuts
- Pecans
- Beans, green
- Sunflower seeds
- Grains and starches
- Wheat flour or bread (of any variety, including whole wheat and white bread)
- Amaranth
- Buckwheat
- Grits
- Wheat germ
- English muffins
- Dairy products and fats
- Chocolate milk (white milk is low in oxalates)
- Soy milk, cheese, or yogurt
- Nut butters like peanut butter or almond butter
- Sesame seeds
- Tahini
- Soy nuts
- Beverages
- Coffee
- Black tea
- Dark beers
Many processed foods like potato chips, soy sauce, hot dogs, soy burgers, and tomato soup may also contain a high amount of oxalate.
Low Oxalate Foods to Enjoy
Although liver and sardines are moderately high in oxalate content, other meats and proteins are great on a low oxalate diet.
Other great foods low in oxalates are:
- Fruits
- Melons
- Mangos
- Bananas
- Avocados
- Apples, peeled
- Vegetables
- Cauliflower
- Zucchini squash
- Lettuce, iceberg
- Cucumber
- Cabbage, white
- Legumes, Nuts, and Seeds
- Coconut
- Water chestnuts
- Grains and starches
- Egg noodles
- Cereals made from corn or rice
- White rice
- Wild rice
- Dairy products and fats
- Cheese
- Milk
- Buttermilk
- Butter
- Mayonnaise (preferably homemade)
- Beverages
- Apple cider
- Grapefruit juice
- Green, herbal, and oolong teas
- Lemonade
- Lime juice
- Pineapple juice
- Wine
- Bottled light beer
In Summary
- Whether for kidney stone prevention or to address other possible chronic health conditions, a low oxalate diet may be the solution.
- On a low oxalate diet, you may notice a decreased risk of kidney stones, improved mineral absorption, diminished joint and muscle pain, improvement in fibromyalgia and interstitial cystitis symptoms, and improvement of autoimmune symptoms.
- Other conditions possibly associated with high dietary oxalates include autism and vulvodynia.
- People who benefit most from a low oxalate diet likely suffer from gut dysbiosis, reduced mineral absorption, and poor urinary tract health.
Before starting a low oxalate diet, it’s best to seek medical advice. If you need a functional medicine doctor who is familiar with oxalates and how it relates to health in the Kansas City area, book an appointment with Jellison Integrative MD, or call 913-568-0608.
Sources
- Traxer, O., Huet, B., Poindexter, J., Pak, C. Y., & Pearle, M. S. (2003). Effect of ascorbic acid consumption on urinary stone risk factors. The Journal of urology, 170(2), 397-401. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/12853784
- Worcester, E. M., & Coe, F. L. (2010). Calcium kidney stones. New England Journal of Medicine, 363(10), 954-963. Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3192488/
- CURHAN, G. C. (1999). Epidemiologic evidence for the role of oxalate in idiopathic nephrolithiasis. Journal of endourology, 13(9), 629-631. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/10608513
- Sorensen, M. D. (2014). Calcium intake and urinary stone disease. Translational andrology and urology, 3(3), 235. Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4708574/
- Kelsay, J. L., & Prather, E. S. (1983). Mineral balances of human subjects consuming spinach in a low-fiber diet and in a diet containing fruits and vegetables. The American journal of clinical nutrition, 38(1), 12-19. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/6305185
- Konstantynowicz, J., Porowski, T., Zoch-Zwierz, W., Wasilewska, J., Kadziela-Olech, H., Kulak, W., … & Kaczmarski, M. (2012). A potential pathogenic role of oxalate in autism. European journal of paediatric neurology, 16(5), 485-491. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/21911305
- Waring, R. H., & Klovrza, L. V. (2000). Sulphur metabolism in autism. Journal of nutritional & environmental medicine, 10(1), 25-32. Full text: https://www.researchgate.net/profile/Rosemary_Waring/publication/232032839_Sulphur_Metabolism_in_Autism/links/0fcfd510119d05a594000000/Sulphur-Metabolism-in-Autism.pdf
- Stewart, C. S., Duncan, S. H., & Cave, D. R. (2004). Oxalobacter formigenes and its role in oxalate metabolism in the human gut. FEMS microbiology letters, 230(1), 1-7. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/14734158
- Harlow, B. L., Abenhaim, H. A., Vitonis, A. F., & Harnack, L. (2008). Influence of dietary oxalates on the risk of adult-onset vulvodynia. The Journal of reproductive medicine, 53(3), 171-178. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/18441720
- Baggish, M. S., Sze, E. H., & Johnson, R. (1997). Urinary oxalate excretion and its role in vulvar pain syndrome. American journal of obstetrics and gynecology, 177(3), 507-511. Abstract: https://www.ncbi.nlm.nih.gov/pubmed/9322615
- Oda, M., Saraya, T., Wakayama, M., Shibuya, K., Ogawa, Y., Inui, T., … & Ota, T. (2013). Calcium oxalate crystal deposition in a patient with Aspergilloma due to Aspergillus niger. Journal of thoracic disease, 5(4), E174. Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3755682/
