Oxalate Overload Is Women's Weight Loss Kryptonite: How To Avoid This 'Anti-Nutrient'

For those of us who have heard of oxalates (the so-called “anti-nutrients” in some plants that can block mineral absorption), the conversation was likely in relation to kidney stones, which are caused by a buildup of oxalate crystals. But wellness insiders now say oxalates can affect our health — and even our weight — in countless other ways.

“Consuming too many oxalates can trigger pain and inflammation all over the body,” says Ken Berry, MD, who experienced oxalate sensitivity after adopting a seemingly healthy diet. The sneaky condition is often called “the great pretender” since it can mimic everything from arthritis pain to rashes, irritable bowel syndrome (IBS), and anxiety. In truth, everyone reacts differently to these plant chemicals that may become toxic when consumed in amounts that exceed our individual capacity to process them. That’s why Dr. Berry says, “Most people who are highly sensitive to oxalate intake have no idea it’s causing their symptoms.” Indeed, Cornell University–trained nutrition expert Sally K. Norton, MPH, author of Toxic Superfoods, contends that up many women in the US over age 50 may have oxalate overload.

Understanding the Theories Around Oxalate Accumulation

Once oxalate crystals enter the bloodstream, they can hide anywhere, even in our master metabolism gland: the thyroid. Citing a 1993 study of 182 deceased women (who had their calcium oxalate crystal levels measured within five hours of death), Sally K. Norton, MPH, states, “Older women have an 85 percent likelihood of oxalate crystals in their thyroid gland, disturbing thyroid function and body-weight regulation.” (Note that the 85 percent statistic referred to women aged 70 or older.) Based on this study, the theory is that the cells closest to these oxalates lose their ability to produce weight-regulating thyroid hormone, even in women without diagnosed thyroid disease. “These crystals can destroy the very machinery of life: cell membranes,” says Norton. But there’s good news too: “When oxalates leave the body, it’s possible to heal tissues and reverse chronic conditions.”

Decades of ill health led Norton to scour libraries at med schools and the National Institutes of Health. She found studies showing oxalate crystals can build up anywhere — including our fat-burning liver, thyroid, and adrenal glands. Animal studies show that oxalate ions can damage any cells they come near, shortening cell lifespan, hampering organ function, and placing metabolic stress on the body. Norton says, “Oxalates can make a mess of our metabolism.”

Oxalate Buildup and Poor Gut Health

Oxalates may also steal minerals from the food we eat, triggering nutrient shortfalls and cravings. What's more, women with poor gut health are most vulnerable to overload. That’s a big group, as experts say most of us struggle with some degree of “leaky gut,” a condition linked to an increase in belly fat. Healthy gut cells limit oxalate absorption, but when the gut lining is damaged, by things like pesticides or NSAIDs (nonsteroidal anti-inflammatory drugs such as ibuprofen), toxins leak through the cell barrier and into the bloodstream, leaving damage in their wake.

Nutrition trends like plant-based eating, which contains healthy foods high in oxalates, have made oxalate overload more common in recent years. Norton adds, “When we pulverize our foods, turning them into nut milks or spinach smoothies, we break open hard-to-digest plant structures that might otherwise limit oxalate’s effects.” Her advice? “When conventional wisdom about healthy eating isn’t working for you, look at oxalates.”

How To Reduce Your Oxalate Intake

The good news: Limiting oxalate intake may allow our kidneys, which remove oxalates from the body, to recover from the toxic backlog. To do that, Norton suggests replacing the highest oxalate foods in your diet with near-identical swaps for a month to see how your body responds. “This is the easiest elimination diet in the world,” promises Norton.

With fewer oxalates in the body, cells may function better and gut health may improve — a factor that may speed fat loss. Women also report improvements in brain fog, cravings, and digestion. Dr. Berry, who follows his own zero-oxalate plan, adds, “In the process of lowering your oxalates, you naturally lower your carb intake to promote fat loss.”

And potential slimming benefits may be just the beginning. Within 10 days of swapping out high-oxalate foods, Norton felt relief from arthritis pain, restless sleep, and bloat. She says, “For the first time in my life, I felt good. As improvements continued, I felt like I was getting younger.”

“There’s no downside to a low-oxalate diet,” adds weight-loss expert David Perlmutter, MD. “It can be a health miracle.”

Note: Additional research finds that a low-oxalate diet does not have weight-loss benefits, and is only beneficial for people trying to reduce their risk of kidney stones. Speak with your doctor before switching to a low-oxalate diet.

Norton's Approach to Cutting Out High-Oxalate Foods

Not all healthy foods are healthy for every body, according to Norton. “I was floored to think that food in my healthy diet, like spinach, Swiss chard, and sweet potatoes, had been making me sick,” she says. Now, she’s spreading the word about oxalate overload, especially to older women since cells weakened by age or chronic inflammation run the greatest risk of oxalate accumulation — and pose the most potential for healing. Dr. Berry adds, “By lowering your oxalates, you’re going to get tremendous relief from inflammation quickly.”

On Norton’s four-week plan, you’ll practice oxalate-aware eating by limiting high-oxalate foods and opting for lower-oxalate alternatives. In general, meat, eggs, cheese, and cabbage are low-oxalate, whereas some seeds, tree nuts, and beans are higher in oxalates. But this approach isn’t about perfection. To see slimming results, follow this gentle step-down approach…

Week 1: Reduce oxalate consumption to less than 200 milligrams (mg) per day (about 60 mg per meal). Start by removing the top offenders, like spinach, beets, and dark chocolate.

Weeks 2 to 4: Reduce oxalates to 100 milligrams or fewer per day, with the goal of getting under 60 mg daily (about 20 mg per meal).

Week 5 and beyond: If you’ve reached your goal, experiment with adding back in some foods during maintenance mode. But know that healing can take time depending on your level of sensitivity. If symptoms return or weight rebounds, reduce oxalates by repeating the prior step.

Additional Tips for Success on a Low-Oxalate Regimen

Though a low-oxalate regimen is not proven to help you lose weight, you may find it useful if you suffer from kidney stones. Check out these tips for reducing the amount of oxalates that build up in your kidneys.

Squeeze a lemon. Start each day consuming citric acid in the form of ? cup of undiluted (full-strength) lemon juice. Norton says, “It helps break down oxalate crystals.”

Get calcium this way. This mineral binds to oxalates, mopping up excess and protecting the kidneys from stones. Aim for a daily dose of 800 to 1,400 mg, depending on your dairy food intake. Look for a product without vitamin D to improve oxalate excretion.

Boil your broccoli. To lower the oxalate content in raw broccoli, boil it for 10 minutes and discard the water. Norton explains, “This breaks down the cell structures so some oxalates can leach into the cooking water.”

Enjoy a healing soak. Some temporary detox symptoms, like headache or fatigue, can occur as oxalates are flushed from the body. Soaking in mineral-rich water can help, says Norton. To do, add ? cup of Epsom salts to a basin of warm water and soak feet for 15 minutes every other day or add 2 cups to a bath twice a week.

How To Know If You Have Oxalate Overload

At-home tests are available to test oxalate stores, but Norton says most of us don’t need them. Instead, consider these signs: joint pain, GI distress, rashes, brain fog, slow recovery from injury, or low bone density. But the most common sign is cloudy or gritty urine. “In the absence of a urinary tract infection, urine with a mirky, foggy-white look is likely filled with oxalates.” If you experience these symptoms, try the tips above.

Note: These symptoms may instead be signs of other conditions.

This content is not a substitute for professional medical advice or diagnosis. Always consult your physician before pursuing any treatment plan.

A version of this article originally appeared in our print magazine, First For Women.