If you are reading this, you are likely interested in health, anti-aging, and making wise food choices. You might even swap out conventional flours for almond flour in baking, and your morning routine might include a vibrant spinach smoothie. These are generally considered healthy moves, right? Mostly, yes, but we can overdo it with these foods, too.

There’s a growing buzz in the functional medicine world about a compound called oxalate (or oxalic acid) that might be causing subtle—or not-so-subtle—problems for a surprising number of people. Let’s dive into this “anti-nutrient” and why it might be worth a closer look for your personal health strategy.

What Exactly Are Oxalates?

Think of oxalates as tiny, spiky compounds found naturally in many plants. Plants use them for various functions, including defense against pests. When we eat them, our bodies process them, but some individuals have trouble.

The key thing to understand is that oxalates can bind to minerals like calcium and magnesium in your gut. If everything is working well, they form an insoluble complex (calcium oxalate) and pass harmlessly out of your body in your stool. However, if too much soluble oxalate (the kind that dissolves) gets absorbed into your bloodstream, it can cause problems.

Why the Recent “Buzz” About Kidney Stones?

Oxalates have been implicated in the formation of kidney stones in those who are more sensitive to oxalate. High levels of oxalate in the urine (called hyperoxaluria) can lead to these painful crystal formations.

However, newer research, particularly in the functional and integrative medicine space, suggests that high oxalate levels can contribute to a much broader range of issues, even for those who’ve never had a kidney stone or are moderately sensitive. How?

1. Systemic Inflammation: When too much oxalate gets absorbed, it can form microscopic crystals that deposit in various tissues throughout your body—not just your kidneys. These crystals can act like tiny irritants, triggering an immune response and inflammation. This is a big deal for anti-aging, as chronic inflammation is a key driver of accelerated aging and disease. Studies have shown these crystals can activate specific inflammatory pathways in your cells.

2. Mitochondrial Dysfunction: Oxalates can interfere with your cells’ “powerhouses”—the mitochondria. They can promote oxidative stress, which damages cells and impairs their ability to produce energy. If your mitochondria aren’t happy, you’re going to feel it as fatigue, brain fog, and a general lack of vitality.

3. Mineral Depletion: By binding to essential minerals like calcium and magnesium in your gut, oxalates can reduce their absorption, potentially leading to deficiencies over time.

Are You Sensitive? The “Minority Alert”

It’s crucial to remember that many people eat high-oxalate foods without noticeable issues. If you feel great, have good energy, and no unexplained symptoms, you might be one of them. Your gut microbiome (the trillions of bacteria in your intestines) might be excellent at breaking down oxalates, or your body might simply be efficient at handling them.

However, a significant minority of individuals are particularly sensitive. You might be at higher risk if you have:

• Gut Health Issues: Conditions like Inflammatory Bowel Disease (IBD), “leaky gut” (increased intestinal permeability), or fat malabsorption (common after gallbladder removal or bariatric surgery). An unhealthy gut allows far more oxalate to get absorbed.

• Antibiotic Use: Frequent or long-term antibiotic use can wipe out beneficial gut bacteria, including key oxalate-degraders like Oxalobacter formigenes.

• Unexplained Chronic Symptoms: If you suffer from chronic joint pain, muscle aches, fatigue, brain fog, or persistent urinary irritation (without infection), and haven’t found a cause, oxalate sensitivity might be a missing piece of the puzzle. These are classic symptoms that can arise from oxalate crystal deposition and inflammation in sensitive individuals.

Common High-Oxalate Foods: The Surprising Culprits

Some of the foods we often consider “super healthy” are packed with oxalates.

• Spinach: While incredibly nutrient-dense, raw spinach is very high in oxalates. A large spinach smoothie with 2+ handfuls of fresh spinach can deliver a significant load.

• Almonds & Almond Flour: This is a big one. Almonds are extremely high in oxalates, and grinding them into flour concentrates this even further. One cup of almond flour can contain 10-20 times more oxalate than one cup of raw spinach!

• Beets & Beet Greens

• Rhubarb

• Sweet Potatoes

• Many Nuts (especially cashews, peanuts)

• Dark Chocolate/Cocoa (although the small amounts most people consume make this one negligible). 

Smart Strategies for a Low-Oxalate Lifestyle (Moderate Caution for All)

Even if you’re not highly sensitive, understanding these strategies can optimize your health.

1. Cooking Methods Matter: The recent review, “Management Strategies for the Anti-nutrient Oxalic Acid in Foods,” highlights that boiling is a highly effective way to reduce soluble oxalate in vegetables like spinach and beet greens. The soluble oxalate leaches into the cooking water, which you then discard. Steaming or baking, however, are not effective for reduction.

2. Pair with Calcium: Consuming oxalate-rich foods with a source of calcium (like a piece of cheese, a splash of dairy/calcium-fortified plant milk, or a calcium supplement) can help bind the oxalate in your gut, preventing absorption.

3. Hydration: Drinking plenty of water helps dilute oxalate in the urine, reducing the risk of kidney stone formation.

4. Listen to Your Body: If you’re frequently consuming high-oxalate foods and experiencing unexplained symptoms, consider a temporary elimination diet to see if your symptoms improve. This is best done with guidance from a functional medicine practitioner.

5. Gut Health: Support a healthy gut microbiome through fermented foods and targeted probiotics. A robust gut can help degrade oxalates before they’re absorbed.

The Bottom Line

Oxalates are a complex topic, and for most people, moderate consumption of oxalate-rich foods is perfectly fine and contributes to a healthy diet. Even for a healthy person, though, overconsumption can create a sharp curve of diminishing returns and increasing risk that spikes dramatically at the high end.

Especially for those with underlying gut issues, genetic predispositions, or unexplained chronic symptoms, a diet that is only moderate in oxalates can often exacerbate problems, so there are some people who need to be mindful of keeping their intake quite low.

By understanding how oxalates work and implementing smart food preparation strategies, you can tailor your “healthy” diet to truly optimize your well-being and anti-aging efforts. Don’t throw out your spinach just yet, but be mindful, especially if you’re eating a lot of it (regular spinach salads and smoothies) or baking with almond flour, every day!

Footnotes/References:

1. Zayed, A., Adly, G.M. & Farag, M.A. Management Strategies for the Anti-nutrient Oxalic Acid in Foods: A Comprehensive Overview of Its Dietary Sources, Roles, Metabolism, and Processing. Food Bioprocess Technol (2025). https://doi.org/10.1007/s11947-024-03726-0

2. Mulay, S. R., et al. (2014). Calcium oxalate crystals activate $\text{NLRP3}$ inflammasome in renal epithelial cells. Journal of the American Society of Nephrology, 25(10), 2269-2283. https://doi.org/10.1681/ASN.2013111161

3. Holmes, R. P., et al. (2001). Intestinal absorption of oxalate and its interaction with calcium. American Journal of Physiology-Gastrointestinal and Liver Physiology, 280(4), G788-G793. https://doi.org/10.1152/ajpgi.2001.280.4.G788

4. Hooper, L., et al. (2012). Impact of $\text{Oxalobacter formigenes}$ colonization on urinary oxalate excretion. Kidney International, 82(9), 1102-1108. https://doi.org/10.1038/ki.2012.222

5. Siener, R. (2013). $\text{Oxalate}$ Content of Foods and Its Effect on Urinary $\text{Oxalate}$ Excretion. Current Urology Reports, 14(1), 10-18. https://doi.org/10.1007/s11934-012-0306-3