Oxalate Overload: 5 Careful Lessons on Healthy Food
Oxalate overload was not a phrase I expected to find at the centre of my “healthy eating” story.
For years, I made a green smoothie most mornings. Spinach. Frozen banana. Almond milk. Chia seeds. Maybe turmeric for the anti-inflammatory benefits. I thought I was doing something obviously good for my body.
Then I went keto, started reading more deeply about food, and came across Sally K. Norton’s work on oxalates in Toxic Superfoods. I had to sit down.
Because almost everything in that smoothie, the spinach, almonds, chia seeds and turmeric, is, according to Norton’s research, among the higher-oxalate foods. Suddenly a list of symptoms and odd body niggles I had been living with for years started to look different.
This is personal note-taking, not medical advice. Oxalates are a health rabbit hole, and I am still learning. But oxalate overload gave me a useful question to ask: what if some “healthy” foods are only healthy for some bodies, in some amounts, at some times?
What Are Oxalates? (And Why You’ve Probably Never Heard of Them)
Oxalates – or oxalic acid – are tiny crystals that certain plants make as a defence mechanism. Think of them as invisible thorns inside the food. When you eat them in small amounts, your kidneys filter them out and you pee them away. No problem.
But if you eat high-oxalate foods repeatedly, over months or years? Your body can’t keep up. The crystals start accumulating in your tissues – not just your kidneys, where they cause kidney stones, but everywhere. Joints. Muscles. The thyroid. The brain. The skin.
Norton spent years as a nutrition researcher at Cornell before her own health collapsed from eating a “perfect” plant-based diet. Joint pain. Fatigue. Brain fog. It took her years to connect the dots back to oxalates.
Toxic Superfoods is what she found.
The Shock List
Here’s what made me put the book down and stare at the wall.
The foods with the highest oxalate loads aren’t junk food. They’re the foods we’re constantly told to eat more of:
- Spinach – the worst offender, by far. One cup of raw spinach contains as much as 656mg of oxalate. The recommended “safe” daily limit is under 60mg.
- Almonds and almond flour – almond flour contains around 400mg per half cup. I’d been baking with this religiously since going keto.
- Swiss chard, beet greens – very high. Not bothered in the slightest about those. Ha, finally one I’m not guilty of eating! Relief.
- Dark chocolate / cacao – high. The hardest truth for me and this will be the hardest to give up on… Not there yet!
- Turmeric – high (yes, really). I’d been drinking a “golden paste” hot drink religiously every night for over a year!
- Chia seeds – high. I went through a phase of drinking chia seeds soaked in water every day!
- Sweet potatoes – high. We thought these were so much healthier than potatoes!
- Peanuts – high. Love them. Can’t look at them in the same way anymore.
The “healthy eating” world has built a cathedral around these foods. Green smoothies with spinach. Dark chocolate as a health food. Almond flour as the keto gold standard. Turmeric lattes for inflammation.
Norton’s research says: not so fast.
Oxalate Overload Symptoms I Started to Notice
This is where it gets uncomfortable.
Because the symptom list Norton gives for oxalate overload is long – and remarkably familiar:
- Chronic joint pain and stiffness
- Fatigue and brain fog
- Anxiety and irritability
- Poor sleep
- Gut problems: bloating, IBS, reflux
- Skin rashes or sensitivity
- Muscle pain and weakness
- Frequent bladder or urinary issues
- Kidney stones (the famous one – but just the tip of the iceberg)
I’m not suggesting that everyone with these symptoms has an oxalate problem. But if you eat the foods above regularly and you’ve had persistent, unexplained symptoms that doctors can’t quite pin down… it’s worth understanding oxalate overload.
How I’ve Changed My Eating
When I went keto in December 2025, I was already trying to avoid inflammatory foods. But reading Norton added a third filter to my approach: keto + low oxalate + low lectin (from Gundry’s The Plant Paradox – yet to read this one, but Ede warns profusely about lectins in her book, Change Your Diet, Change Your Mind).
The practical changes:
Almond flour is out. This was the big one. Almond flour is the queen of keto baking, but it’s also one of the highest-oxalate foods in existence. My swap: coconut flour (only 9mg per serving, versus almond flour’s 400mg). It behaves differently – you need about a quarter the amount and more eggs — but it works.
Spinach is out. I thought I’d miss it. I don’t. Rocket, bok choy, cos lettuce, broccoli – there are plenty of low-oxalate greens that taste better anyway.
Cocoa/chocolate is (not yet) out! This one stings. But there are substitutes: carob powder, mesquite, chicory-based chocolate drinks that genuinely scratch the itch.
Macadamia nuts are in. The only truly safe nut by oxalate standards. Conveniently also delicious.
One big gotcha: go slow. Norton is very clear about this – when you reduce oxalate intake suddenly, your body starts clearing out the stored crystals. This is called “oxalate dumping” and it can temporarily feel awful: rashes, intense pain, headaches, anxiety. The key is to reduce gradually. Think of it as emptying a bathtub through a tiny drain – slow and steady.
What I’m Still Learning
I want to be honest: this is a deep rabbit hole and I’m not at the end of it.
Norton’s research on oxalate overload is not mainstream. Many nutritionists will say healthy people do not need to worry much about oxalates, and for many people that may be true. For people who are sensitive, have kidney-stone history, or recognise the pattern in their own body, the information can still be worth discussing with a practitioner.
I’m three months into low-oxalate keto as I write this. Some things have improved. Others I’m still watching. I’m not here to convert you – I’m here to share what I’m finding. And for me personally, something has switched in my brain. You can’t ignore oxalate overload once you’ve seen the evidence even if people around me might think I’ve become orthorexic. I am and I have – but I’d rather be that than take unnecessary risks. You are what you eat after all! And in our modern world, we have plenty – too much, I think — which makes people feel that they’re missing out when we actually live in an over-consumption world. My humble opinion, not the truth!
What to Take From This
- Know the high-oxalate foods — Spinach, almonds (including almond flour and milk), chard, Swiss chard, beet greens, dark chocolate, turmeric, chia seeds, sweet potatoes, peanuts. These are the main culprits. Oxalate overload builds up silently.
- Swap almond flour for coconut flour — Use ¼ the amount, add extra eggs. Your keto baking will survive.
- Never go cold turkey — Reduce gradually to avoid a painful oxalate dumping reaction.
- Get your avocados properly ripe — A ripe Hass avocado has 7mg of oxalate. A firm unripe one has 50mg. Same fruit, seven times the oxalate load. Always wait for ripe.
- Read the book if this resonates — Norton’s writing is clear, the research is thorough, and the recipes at the back are genuinely useful.
- Watch your total daily load — The “safe” limit is under 60mg a day. Most people eating “healthy” Western diets are at 130–220mg. Some plant-based enthusiasts are at 600mg+.
Why This Belongs in “Body”
My blog is organised around my Tree of Life: Roots, Body, Mind, Heart, Soul, Purpose. Each section represents a part of my life that needs attention.
This belongs in Body because it’s about the fundamental fuel I’m putting into my physical self — and the realisation that some of what I thought was nourishing was actually creating a problem. Oxalate overload symptoms are exactly the kind of thing The Body section is for — tracking what I’m learning about health, nutrition, fitness, and how to support this particular body at this particular stage of life.
I don’t have it all figured out. I’m learning, adjusting, paying attention. But I’m glad I read this book – even if it did ruin my evening square of dark chocolate addiction…
Related Notes on Food, Energy and the Body
If this note made you rethink “healthy” food too, these are the companion Body notes I would read next:
- Keto and genetics: why the same diet can work differently for different bodies
- Georgia Ede on food and mental health
- Glucose Revolution by Jessie Inchauspé: the hacks that changed my energy
- The Hormone Repair Manual by Lara Briden: listening to what my body was saying
Notes from Soph | Learning, not perfection.
Have you ever had unexplained symptoms that turned out to have a surprising dietary cause? I’d love to hear — leave a comment or reach out.
Source note: This is a personal reading reflection on Sally K. Norton’s book and my own food experiments. It is not a diagnosis or a treatment plan.
Book Details:
Toxic Superfoods: How Oxalate Overload Is Making You Sick — and How to Get Better — Sally K. Norton, MPH
Published 2023 | Rodale Books
📚 Amazon.fr https://amzn.to/4cRyD7l
🎧 Audible https://www.audible.co.uk/pd/Toxic-Superfoods-Audiobook/B09FFTTT5W?source_code=ASSGB149080119000H&share_location=pdp
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