If you’ve been spending any time in the wellness world recently, you may have heard the word oxalates mentioned, often alongside concern, confusion, or strong opinions.
Spinach. Almonds. Chia seeds. Sweet potatoes.
All foods we consider “healthy”.
All foods that contain oxalates.
All foods we often also combine in green smoothies, ‘chia puddings’ etc.
So what are oxalates? Should you be worried? And how do they fit into a balanced, hormone-supportive diet?
Let’s unpack this scientifically, and practically.
What Are Oxalates?
Oxalates (oxalic acid) are naturally occurring compounds found in many plant foods. They are also produced in small amounts by the body as part of normal metabolism.
Chemically, oxalates bind readily to minerals such as calcium, iron and magnesium. When oxalate binds with calcium, it forms calcium oxalate — the most common type of kidney stone.
However, context matters.
For most healthy individuals, oxalates are processed and eliminated without issue. They become relevant when intake is consistently high, mineral balance is compromised, or certain digestive or metabolic vulnerabilities are present.
Where Are Oxalates Found?
Oxalates are particularly concentrated in certain plant foods, including:
- Spinach
- Swiss chard
- Beetroot
- Almonds and almond products
- Cashews
- Sesame and tahini
- Chia seeds
- Cocoa and dark chocolate
Other foods contain moderate or low levels.
(You can view a full breakdown of high, moderate and low oxalate foods in my printable table here → Oxalate Foods List
The key takeaway?
Oxalates are found in many nutritious foods — which is why elimination is rarely the answer.
When Do Oxalates Matter?
For most people, they don’t.
However, oxalate awareness becomes relevant in certain scenarios:
1. Kidney Stones
Around 70–80% of kidney stones are calcium oxalate stones (Khan et al., 2016). In individuals prone to stone formation, reducing dietary oxalate and ensuring adequate calcium intake may help lower recurrence risk.
Importantly, studies show that low dietary calcium can increase stone risk because calcium in the gut binds oxalate and prevents absorption (Curhan et al., 1997). In other words, cutting calcium is not protective. Adding calcium rich foods to your meal, such as broccoli, sardines, and dairy (if you tolerate it) is key.
Gut Disorders, Malabsorption & Why Oxalates Sometimes Matter
In my clinic, I work with many women dealing with underlying gut imbalances: bloating, IBS-type symptoms, post-antibiotic disruption, food sensitivities, or chronic digestive stress.
When gut function is compromised, oxalate handling can change.
Normally, calcium in the gut binds to oxalate from food and helps eliminate it in stool. But in cases of inflammation or fat malabsorption (very common ‘issues’), calcium may bind to fat instead, leaving more oxalate available for absorption: a process sometimes referred to as enteric hyperoxaluria (Nasr et al., 2008).
In simple terms: a stressed or inflamed gut may absorb more oxalate than a resilient one.
This doesn’t mean women with gut symptoms need to avoid healthy vegetables. But when I see clients with digestive imbalance who are also eating large amounts of spinach, almond products and chia daily, gentle rotation rather than restriction can often be helpful.
One client went as far as rotating ‘carnivore’ days when she would eat mostly meat/fish and other animal protein, with little vegetables, when she felt her gut was struggling to digest starches and fibre.
3. “Stacking” High-Oxalate Foods
In practice, I often see issues arise not from one food, but from stacking/accumulation:
- Spinach daily
- Almond milk
- Almond butter
- Chia seeds
- Cocoa
All in one day, repeated daily.
Each food individually? Nutritious.
Together, repeatedly? A significant oxalate load.
This is where balance and rotation become powerful tools.
Common Symptoms Sometimes Associated with High Oxalate Intake
It’s important not to over-attribute symptoms to oxalates. However, in sensitive individuals, high intake may be associated with:
- Recurrent calcium oxalate kidney stones
- Bladder irritation or urinary urgency
- Digestive discomfort in those with compromised gut integrity
- Vulval irritation in susceptible individuals
These symptoms are not always purely caused by oxalates, however, but cutting out high oxalate foods for even a couple of weeks should give a good indication of sensitivity.
Oxalates and Nutrient Absorption
Oxalates bind minerals, particularly calcium and iron, potentially reducing their absorption.
However, this effect is usually modest within a varied diet.
Practical strategies include:
- Eating calcium-containing foods alongside higher-oxalate foods (broccoli, sardines, dairy when tolerated, parsley, fresh herbs, green leafy vegetables such as kale or cabbage etc)
- Avoiding excessive reliance on one or two high-oxalate food
- Rotating greens rather than consuming the same one daily
- Maintaining good hydration
In addition, boiling certain high-oxalate vegetables (like spinach) can reduce oxalate content significantly, as oxalates are water-soluble (Noonan & Savage, 1999).
Should You Avoid Oxalates?
For most people: there’s no need to avoid them completely, because oxalate-containing foods often provide:
- Fibre
- Phytonutrients
- Antioxidants
- Folate
- Magnesium
- Vitamin C
- Polyphenols
Removing them entirely can reduce dietary diversity and nutritional quality.
Instead, and even in individuals with a history of kidney stones, a moderate reduction (often aiming for under ~100 mg/day) may be recommended, but complete elimination is rarely required.
As with most areas of nutrition, nuance and balance matter.
A Practical Framework: Rotation Over Restriction
Instead of fear-based elimination, consider these principles:
1. Rotate Greens
Spinach one day, rocket the next, kale another.
2. Moderate “Superfood” Portions
Chia pudding every day? Consider alternating with hemp or flax seeds.
3. Pair with Calcium
Including adequate dietary calcium reduces oxalate absorption.
4. Stay Hydrated
Dilute urine reduces stone formation risk.
5. Avoid Daily Stacking
Be mindful of almond milk + almond butter + spinach + cocoa all in one day.
Variety reduces cumulative load of oxalates.
Oxalates in the Bigger Picture of Cleansing
The body has built-in detoxification pathways: liver, kidneys, gut, lymphatic system.
Supporting those pathways involves:
- Hydration
- Adequate protein
- Mineral balance
- Regular bowel movements
- Stress regulation
Not extreme elimination.
Oxalate awareness fits within this broader lens of intelligent nourishment.
Of course, if you struggle in either of these areas, this is where your focus needs to be.
Final Thoughts: Balance Wins
Oxalates are not villains. In fact, they are naturally occurring plant compounds that become relevant primarily when:
- Intake is excessive
- Gut health is compromised
- Mineral balance is insufficient
- Or kidney stone history exists
For most women focusing on hormone balance, gut resilience, and metabolic health, the goal is not removal, it is rotation and variety.
Finally, if you’d like a practical breakdown of foods by oxalate level, you can access my printable guide here:
→ Oxalates Food Listhttps://newleafnutrition.co.uk/oxalates-list-of-foods/
References
Curhan, G. C., Willett, W. C., Rimm, E. B., & Stampfer, M. J. (1997). A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. New England Journal of Medicine, 328(12), 833–838.
https://www.nejm.org/doi/full/10.1056/NEJM199303253281203
Khan, S. R., Pearle, M. S., Robertson, W. G., et al. (2016). Kidney stones. Nature Reviews Disease Primers, 2, 16008.
https://www.nature.com/articles/nrdp20168
Nasr, S. H., D’Agati, V. D., & Said, S. M. (2008). Oxalate nephropathy: a review. Clinical Journal of the American Society of Nephrology, 3(6), 1676–1683.
https://cjasn.asnjournals.org/content/3/6/1676
Noonan, S. C., & Savage, G. P. (1999). Oxalate content of foods and its effect on humans. Asia Pacific Journal of Clinical Nutrition, 8(1), 64–74.
https://apjcn.nhri.org.tw/server/APJCN/8/1/64.pdf
Photo by Alisha Mishra: https://www.pexels.com/photo/selective-focus-photography-of-vegetable-shake-on-brown-wood-board-1346342/