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Is Your Spinach Smoothie Making You Sick?

Need-to-know information about "oxalate overload"


By Sally K. Norton, MPH

Author of Toxic Superfoods


Appreciating the pitfalls of plant toxins is a new paradigm in nutrition. It is possible—easy even—to over-consume plant foods and become sick because of the natural toxins they contain.


But we in the profession did not learn this in school. Despite my nutrition degree from Cornell University, a master’s degree in public health, and managing a large integrative medicine education project at the University of North Carolina Medical School at Chapel Hill, I did not know that a variety of plant foods could cause a diverse variety of health problems.


If you’re a conscientious eater with a diet featuring “wholesome” foods like spinach smoothies, chard, almonds, beans, sweet potatoes, turmeric, and quinoa, you need to hear my story.


Despite decades of enthusiastic devotion to healthy eating, exercise, meditation, and “clean” living, I was not the picture of vitality and sturdiness. I had gut problems, joint pain, inflammation, a lumpy thyroid, and other symptoms that were stumping my doctors. I was beyond exhausted—unable to read with comprehension, unable to work. A high-tech sleep study showed that I was waking up 29 times every hour. Medications did nothing to improve the situation. I was stuck, and no one could help.


One of my occasional symptoms, genital pain, inspired a google search that brought up an unfamiliar and seemingly non-scientific notion that oxalates in foods can cause pain and problems with connective tissues. Oxalates, a natural chemical, are known to cause kidney stones and urinary tract problems. Initially, that didn’t seem a fit for me; I’d never had a kidney stone or bladder symptoms.


What are oxalates and why are they bad? 


Oxalates are a family of compounds that come from a tiny natural ionic acid and a reactive chelator called oxalic acid—a bleach and rust-removing cleaning chemical in use for over 250 years. Oxalic acid readily hooks up with minerals, such as potassium, calcium, magnesium, and iron. These oxalate salts easily form crystals. Oxalates are ubiquitous in nature—plants and soil fungi create oxalic acid.


Oxalates ingested from plant foods grab and hold nutritionally valuable minerals in the digestive tract, making it difficult for the body to absorb minerals. Some ingested oxalic acid passes into the bloodstream, where it can also bind minerals. The two-pronged mineral depletion can cause serious problems for long-term health.


In the body, oxalates have a range of additional toxic actions, which directly harm cells, block enzymes, and create oxidative stress. They stick to the fats and proteins that make up cell membranes, especially if cells are inflamed, old, wounded, or dying. Over time, the constant use of foods with oxalate—potatoes, peanuts, almonds, chocolate, beans, and spinach—so ubiquitous in our modern diets—leads to accumulation and toxicity.


Even relatively moderate levels of oxalate in a habitual diet can fuel the customary aches and pains of life: digestive distress, inflamed joints, repeated infections, chronic skin issues, brain fog or mood problems, as well as health declines associated with “normal” aging. I’m not special in this ability to be sickened by oxalates. My mistake was in following all the “best” advice about eating right.



Good News


The surprising health benefits of low-oxalate eating may include the dramatic improvements I saw: far less pain and improved sleep, energy, concentration, and mood—even reversal of osteopenia. I had to consistently shun my beloved sweet potatoes and trusted chard to get there, and my recovery is still unfolding after 9 years.


I am not alone in the ability to recover from the mess that is oxalate poisoning. Many people have found some relief from—or even reversed—a surprisingly diverse variety of conditions simply by swapping their high-oxalate foods for low-oxalate alternatives. In the long term, avoiding oxalates can potentially prevent injury, arthritis, and dementia. 


Opportunities Abound


Humanity has lost touch with nature. We’re not seeing the reality that healthy eating often fails to make us truly well. We’re preoccupied with fears and our forgone solutions—solutions that are failing us.


Now that oxalates’ toxic secrets are exposed, we’re gifted with the opportunity to grow our awareness of the natural world. New attention on oxalate toxicity is an opportunity for a breakthrough in nutrition that makes a real difference for human health. Most importantly, learning about oxalate toxicity is an opportunity for personal healing.


If we allow ourselves to let this idea sink into our consciousness, accept the truth that the majority of plants contain problematic compounds, and follow nature’s lead, some good will come of it.


What does a low-oxalate diet look like?


“Low-oxalate” does not mean “no-oxalate,” so you don’t have to be perfect. The key is to know what you’re eating and how much, and to choose your daily staples from nourishing foods with less potential to create chronic problems. It’s simple. Try turnips and cauliflower in place of potatoes, pumpkin seeds or cheese in place of almonds and peanuts, or to use romaine lettuce or arugula instead of spinach or mixed baby greens in your salads and smoothies.


Animal foods have always been an important staple for humans and are generally free of oxalate and other plant toxins. Including ample animal foods in your diet is not only the species-appropriate thing to do, it’s smart, oxalate-free nourishment.


Because the diet change can trigger the release of oxalate from tissues, it’s important to go slow with reducing your oxalate intake and it’s paramount to get support from professionals if you have serious health concerns.  


With just a bit of information, you’ll find it simple and inexpensive to swap out high-oxalate foods for low-oxalate foods. Try it for a few months and see what it does for you. Time to relief is different for everyone, but you might be surprised how much better you feel. 

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Sally K. Norton, MPH holds a nutrition degree from Cornell University and a master’s degree in Public Health. Her path to becoming a leading expert on dietary oxalate includes a prior career working at major medical schools in medical education and public health research.  Her book Toxic Superfoods: How Oxalate Overload is Making You Sick-and How to Get Better releases January 2023 and it is available for pre-order HERE.  For more information, visit or follow Sally on Instagram (@sknorton) (@toxicsuperfoods_oxalate_book) and Facebook (@BeFreeToThrive).

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