First it was gluten.

Then lectins.

Then seed oils.

Recently, oxalates have entered the spotlight, with some articles suggesting they cause everything from mineral deficiencies to gut damage and chronic fatigue.

Should we be concerned? Spoiler alert… probably not.

What Are Oxalates?

Oxalates (or oxalic acid) are naturally occurring compounds found in many plant foods. Plants produce them as a defence mechanism against pests and environmental stress.

Foods that contain higher amounts of oxalates include:

• Spinach

• Beetroot leaves

• Swiss chard

• Rhubarb

• Almonds

• Cocoa

• Sweet potatoes

• Buckwheat

Because oxalates can bind to minerals such as calcium, iron and magnesium, they’re often labelled as “antinutrients.” This sounds alarming, but the reality is more nuanced.

Do oxalates block mineral absorption?

Technically, yes — oxalates can bind to minerals and reduce their absorption. But the key point is that this happens within the specific food they’re attached to, not across your entire diet.

Take spinach as an example; spinach contains calcium, but much of that calcium isn’t absorbed because it’s bound to oxalate. However, this doesn’t mean eating spinach will cause a calcium deficiency. Most people get calcium from many other foods throughout the day.

In real-world diets, mineral absorption depends on overall dietary patterns, not individual compounds. If oxalates significantly impaired mineral status, we would expect populations eating lots of vegetables to show widespread deficiencies. This isn’t what we see.

Where oxalates do matter: Kidney stones.

The strongest scientific link between oxalates and health is kidney stones. About 70–80% of kidney stones contain calcium oxalate crystals. For people who are prone to kidney stones, reducing dietary oxalate intake may be recommended alongside other strategies such as:

• Drinking more fluids

• Reducing excessive sodium intake

• Ensuring adequate calcium intake

However, for people with no history of kidney stones, oxalates are generally not considered a major health concern. Clinical guidelines do not recommend widespread oxalate restriction for the general population.

What about claims linking oxalates to fatigue, gut damage or joint pain?

Some [wellness] articles suggest oxalates contribute to issues such as:

• “Leaky gut”

• Joint pain

• Fatigue

• Skin problems

There is no evidence that normal dietary intakes of oxalates cause any of these issues. Much of the evidence comes from case reports, small studies or anecdotal accounts which fail to highlight additional confounding variables. Evidence like this can be useful for generating hypotheses, but they certainly don’t establish causation.

At the population level, there is no clear evidence that dietary oxalates cause systemic inflammatory or metabolic problems in healthy individuals.

Taking the “green smoothies” to an extreme.

There is one scenario where oxalates can become an issue: very large (and I mean, extreme), repetitive intakes of high-oxalate foods. For example, consuming large spinach smoothies every day can significantly increase oxalate intake. There are rare case reports of kidney problems linked to extreme dietary patterns like this. But these situations usually involve:

• Very high daily consumption

• Highly restrictive diets

• Underlying health vulnerabilities

These cases are not representative of typical eating habits.

The Bigger Picture

From a public health perspective, the bigger nutritional challenges most people face are:

• Low fruit and vegetable intake

• Low fibre consumption

• High intake of ultra-processed foods

Discouraging plant foods because they contain oxalates risks creating more problems than it solves. Many oxalate-containing foods — such as leafy greens, beans, nuts and whole grains — are consistently linked with improved health outcomes.

“The poison is in the dose.”

Many beneficial plant compounds exist because plants evolved chemical defences. These include:

• Polyphenols

• Glucosinolates

• Lectins

• Oxalates

At normal dietary levels, these compounds are not harmful and may even stimulate beneficial biological adaptations. This concept is sometimes called hormesis — where small amounts of stress trigger protective responses in the body.

Should you avoid oxalates?

For most people, the answer is no. Instead of focussing on restriction, take a balance approach, and simply:

• Eat a varied diet to ensure multiple sources of different vitamins and minerals

• Rotate different fruits and vegetables

• Avoid extreme dietary patterns

Oxalate restriction may be appropriate for individuals who are prone to calcium oxalate kidney stones, but for everyone else, it’s rarely necessary.

In summary…

Oxalates are a natural component of many plant foods. While they can contribute to kidney stones in susceptible individuals, they are unlikely to pose a health risk for most people eating a balanced diet.

Nutrition headlines often magnify small biochemical effects into widespread dietary fears.

In reality, diet quality, variety and overall lifestyle habits matter far more than the presence of a single compound in food.