Oxalates

Could Oxalates Be Affecting Your Health?

You may never have heard of oxalates, but chances are you eat them every day. Found naturally in many healthy foods — from spinach and almonds to sweet potatoes and chocolate — oxalates are a normal part of most diets. For the majority of people, they pass through the body without causing any trouble. But for some, oxalates can quietly contribute to a surprising range of health problems, from kidney stones to chronic pain. This article will help you understand what oxalates are, what symptoms might suggest they are a problem for you, and what you can do about it.

What Are Oxalates?

Oxalic acid is a naturally occurring compound that plants produce as part of their normal chemistry. When you eat these plants, the oxalic acid binds to minerals like calcium and iron in your digestive tract, forming crystals called oxalates. Normally, most of these crystals pass out of your body in stool. A small amount is absorbed into the bloodstream and filtered out by the kidneys into urine.

Problems can arise when the body absorbs too much oxalate, or when the kidneys cannot clear it efficiently. Excess oxalate can then accumulate in urine, tissues, and joints — leading to the health issues described below.

Foods that are particularly high in oxalates include:

Spinach, Swiss chard, and beet greens

Almonds and cashews

Rhubarb

Chocolate and cocoa

Sweet potatoes

Black tea

Soy products

Signs That Oxalates Might Be a Problem for You

Oxalate-related symptoms can be easy to overlook because they mimic many other conditions. Here are some of the most common warning signs to watch for:

Kidney Stones

This is the most well-known oxalate problem. About 80% of all kidney stones are made of calcium oxalate. If you have had a kidney stone — especially more than once — oxalate is a very likely contributor. Symptoms of a kidney stone include severe pain in the back or side, blood in the urine, and a frequent urge to urinate.

Joint Pain and Muscle Aches

Oxalate crystals can deposit in joints and soft tissues, causing pain and stiffness that resembles arthritis or fibromyalgia. If you experience unexplained joint pain, particularly after eating high-oxalate meals, it may be worth exploring the connection.

Chronic Pelvic or Vulvar Pain

Some women with a condition called vulvodynia — chronic pain or burning in the vulvar area with no clear cause — have found relief by reducing oxalate intake. While the research is still developing, a trial low-oxalate diet may be worth discussing with your doctor if you experience this type of pain.

Digestive Symptoms

Bloating, abdominal discomfort, and irregular bowel movements after eating high-oxalate foods can be a sign that your gut is absorbing more oxalate than it should. This is especially common in people with underlying gut conditions like Crohn’s disease, celiac disease, or a history of intestinal surgery.

Fatigue and Brain Fog

While less well-studied, some people report significant fatigue, poor concentration, or mental cloudiness that improves when they reduce oxalate in their diet. Researchers believe this may be related to oxalate’s effects on mitochondria — the energy-producing structures inside our cells.

Who Is Most at Risk?

Anyone can experience oxalate-related issues, but some people are significantly more vulnerable than others. You may be at higher risk if you have any of the following:

• A history of kidney stones, especially calcium oxalate stones
• Inflammatory bowel disease (Crohn’s or ulcerative colitis)
• Celiac disease, even if you are following a gluten-free diet
• A history of gastric bypass surgery
• Frequent antibiotic use, which can disrupt the gut bacteria that break down oxalate
• Low calcium intake or a calcium-restricted diet
• Vitamin B6 or magnesium deficiency
• A diet very heavy in spinach, almonds, or other high-oxalate foods

What You Can Do

If you suspect oxalates may be contributing to your symptoms, the good news is that there are practical steps you can take — many of them simple changes to how you prepare and eat food.

Pair high-oxalate foods with calcium.

This is one of the most effective strategies. Eating a calcium-rich food (like dairy, fortified plant milk, or canned fish with bones) alongside high-oxalate foods causes oxalate to bind to calcium in the gut, preventing it from being absorbed. Counterintuitively, avoiding dairy with high-oxalate meals actually makes things worse.

Boil your high-oxalate vegetables.

Boiling vegetables like spinach and then draining and discarding the water can reduce their oxalate content by 30 to 50 percent. Steaming and roasting are less effective.

Stay well hydrated.

Drinking plenty of water dilutes the concentration of oxalate in urine, reducing the risk of crystal formation in the kidneys. Aim for pale yellow urine throughout the day as a simple guide.

Support your gut health.

A healthy gut lining and a diverse microbiome are your first line of defense against oxalate overload. Certain gut bacteria, particularly Oxalobacter formigenes, naturally break down oxalate before it can be absorbed. Eating fermented foods, a wide variety of fiber, and minimizing unnecessary antibiotic use can help support these beneficial bacteria.

Consider a trial low-oxalate diet.

If you have multiple symptoms that might be oxalate-related, talking to your doctor or a registered dietitian about trying a low-oxalate diet for four to six weeks can be informative. If your symptoms improve noticeably, that is a strong clue that oxalates are involved. This should be done with professional guidance to make sure your diet remains balanced and nutritious.

When to Talk to Your Doctor

Most people with mild oxalate sensitivity can manage their symptoms through dietary adjustments alone. However, you should speak with your healthcare provider if you have had more than one kidney stone, if you have unexplained chronic pain that has not responded to other treatments, or if you have a family history of kidney disease. In rare cases, a genetic condition called primary hyperoxaluria causes the liver to overproduce oxalate regardless of diet — this is a serious medical condition requiring specialized care.

A simple 24-hour urine test can measure how much oxalate you are excreting and help your doctor determine whether elevated oxalate is contributing to your symptoms.

The Bottom Line

Oxalates are not a problem for everyone, and there is no need to fear healthy plant foods. But if you have been struggling with kidney stones, unexplained joint pain, pelvic discomfort, or persistent fatigue — and no one has quite figured out why — oxalates are worth exploring. Simple changes like boiling vegetables, pairing foods with calcium, and drinking more water may make a meaningful difference.

Take care,

David

Oxalate Sensitivity Checklist

Ellen

Ahh, breakfast time! Is it worth it to be stuck in bed just because you get breakfast served to you every morning? It makes me suspicious. She looks pretty happy with her steamed eggs, blood orange slices, and gluten free toast with organic peanut butter.