Are spinach and kale high in oxalates?

Spinach is widely recognized as a high oxalate food, and some other leafy greens can also be significant sources. If you are prone to kidney stones or have kidney disease, a renal dietitian can help you choose lower oxalate options and appropriate portions.

What is oxalate nephropathy?

Oxalate nephropathy is kidney injury linked to oxalate crystal deposition in kidney tissue, sometimes confirmed by biopsy. It is uncommon, but it can be serious, especially when oxalate exposure is very high or absorption is increased due to gut conditions.

Do greens powders have the same issue as green smoothies?

They can, because powders are concentrated forms of plant material and may deliver a larger dose of oxalates per serving than you would expect. Product quality also varies, so third party testing and moderation are practical safeguards.

Can cooking reduce oxalates in greens?

Cooking can reduce soluble oxalates in some vegetables, particularly boiling and discarding the water, though results vary by food and method. If oxalate restriction is relevant to you, ask a clinician or dietitian for a plan tailored to your health history.

Green Smoothies, Oxalates, and Kidney Risk

What most people get wrong about green smoothies

Green smoothies look like the healthiest thing you can do. A blender, a handful of spinach, some kale, maybe Swiss chard, then you drink it and feel like you “won” nutrition for the day.

This video challenges that entire assumption.

The key argument is not that plants are “bad,” or that you should never eat greens. The point is more specific and more practical: when you hyper concentrate certain greens, you also hyper concentrate their anti nutrients, especially oxalates. In some people, that can become a kidney problem, and potentially a joint or whole body problem.

What makes this perspective feel urgent is that it is not framed as theory. The discussion points to medical case reports where heavy green smoothie intake was associated with oxalate nephropathy, meaning oxalate crystal injury to the kidneys, including cases that progressed to dialysis.

Important: If you have kidney disease, recurrent kidney stones, or you are considering a daily green cleanse, it is worth discussing oxalate exposure with your clinician or a renal dietitian before making big diet changes.

Why “healthy” can become risky when it is concentrated

A normal salad is bulky. It takes time to chew. You feel full.

A smoothie bypasses that natural brake.

Blending and juicing make it easy to take in what could be multiple bowls of raw greens in a few minutes. The video’s framing is that this is where problems can start, not because spinach is evil, but because your kidneys still have to process what you swallowed.

The discussion also pushes back on the common “plant based equals harmless” logic. Plants can be nutritious, but they also contain compounds that help the plant defend itself. When those compounds are concentrated, susceptible people may notice consequences.

Oxalates, explained in plain language

Oxalates (oxalic acid and oxalate salts) are natural compounds found in many plants. In the body, oxalate can bind with minerals like calcium, forming calcium oxalate crystals. Those crystals are a common component of kidney stones.

Here is the practical connection the video emphasizes: some of the most popular smoothie greens are also among the highest oxalate foods, including spinach, Swiss chard, and some preparations of kale.

This is not fringe. Kidney stone education from major medical centers routinely discusses limiting high oxalate foods for people prone to stones, including spinach. For example, the National Kidney FoundationTrusted Source explains that calcium oxalate stones are the most common type and dietary oxalate can matter for some people.

Oxalate is not only “from food,” either. The body can also produce oxalate, and gut microbes help degrade some oxalate before it is absorbed. That is one reason the video repeatedly returns to the idea of susceptibility, meaning two people can eat the same smoothie and have very different outcomes.

Did you know? Calcium oxalate is the most common component of kidney stones, according to the National Institute of Diabetes and Digestive and Kidney DiseasesTrusted Source.

What “oxalate nephropathy” means

Most people hear “oxalate” and think “kidney stones.” Oxalate nephropathy is different and more severe.

In oxalate nephropathy, oxalate crystals deposit in kidney tissue, including the tiny tubes (tubules) that help filter and process urine. This can trigger inflammation and kidney injury. The video describes biopsy images showing crystals in the renal tubules, a vivid reminder that the issue is physical and measurable, not just a wellness debate.

Research reviews describe oxalate nephropathy as uncommon but serious, and often linked to high oxalate intake or increased absorption (for example, certain gut conditions). For a medical overview, see this review on enteric hyperoxaluria and oxalate related kidney injury in the Clinical Journal of the American Society of NephrologyTrusted Source.

The “smoothies to dialysis” cases, and what they do and do not mean

The most striking part of the video is its focus on case reports.

A case report cannot prove that smoothies always cause kidney failure. But it can show a plausible pattern, especially when kidney biopsy finds calcium oxalate crystals and the diet history includes extremely high oxalate intake.

Case report: “Green smoothie cleanse causing acute oxalate nephropathy”

One paper highlighted is titled “Green smoothie cleanse causing acute oxalate nephropathy.” It was published in the American Journal of Kidney Diseases and describes a temporal association between an oxalate rich green smoothie cleanse and kidney injury, with biopsy showing calcium oxalate crystals in kidney tubules.

The video notes important context from the case: the person had predisposing factors, including a remote history of gastrointestinal bypass surgery and recent prolonged antibiotic therapy. In other words, the smoothie cleanse may have landed on top of a body already primed to absorb more oxalate than average.

What the research shows: The American Journal of Kidney Diseases case report “Green smoothie cleanse causing acute oxalate nephropathy” describes biopsy confirmed oxalate crystal deposition after a green smoothie cleanse and progression to severe kidney disease in that patient. You can find the citation details via the journal site: American Journal of Kidney DiseasesTrusted Source.

Case report: “From smoothies to dialysis”

The video also references another report described as “From smoothies to dialysis,” emphasizing how shocking it can be to connect “healthy smoothies” with end stage kidney disease.

Another story discussed involves a 54 year old male with type 2 diabetes who regularly consumed high oxalate foods such as spinach and kale smoothies, believing they were beneficial for diabetes. Despite hemodialysis, the person did not recover renal function and remained dialysis dependent.

That detail matters because it shows how health motivated behaviors can backfire when the mechanism is misunderstood. It also underscores why “I eat clean” does not always mean “I am protected,” especially for kidneys.

What these cases do not prove

These reports do not mean everyone should fear spinach.

They also do not mean that a single smoothie will damage your kidneys. The pattern described is repeated, heavy intake, often as a cleanse or daily habit, sometimes with additional risk factors.

Still, the video’s practical conclusion is hard to ignore: if you are drinking large green smoothies every day, it may be worth reassessing the risk to benefit ratio.

Who may be more vulnerable (kidneys, gut, and beyond)

The video frames oxalate overload as a “susceptible people” issue. That is a useful lens, because it moves the conversation away from food fear and toward risk screening.

Some groups may want to be especially cautious.

People with a history of kidney stones. If you form calcium oxalate stones, high oxalate smoothies can be a straightforward way to raise urinary oxalate. Many kidney stone prevention guidelines advise moderating high oxalate foods and focusing on hydration and adequate calcium with meals. The NIDDK kidney stone guidanceTrusted Source discusses diet strategies commonly used in prevention.

People with chronic kidney disease (CKD) or reduced kidney function. When kidney filtration is already impaired, extra crystal burden is not a great experiment to run on yourself. A clinician can help tailor diet to your lab values and stage of disease.

People with gut surgery or fat malabsorption. The video calls out prior gastrointestinal bypass. This connects to a known phenomenon called enteric hyperoxaluria where oxalate absorption can increase. The CJASN review on enteric hyperoxaluriaTrusted Source explains why certain GI conditions can raise risk.

People who recently used prolonged antibiotics. The video mentions antibiotics as a predisposing factor in a case report. One plausible pathway is disruption of gut microbes that degrade oxalate, such as Oxalobacter formigenes, although individual responses vary.

People who do “cleanses,” fasting plus juicing, or high frequency greens powders. The common theme is concentration, repetition, and sometimes low overall calorie intake, which can also mean less calcium intake with meals, plus dehydration.

The video also floats symptoms beyond kidneys, such as joint pain and migraines, as reasons some people explore lower oxalate approaches. Evidence here is less clear than for kidney stones, but the practical suggestion is to consider oxalate load as one variable if you have persistent symptoms and a high raw greens intake.

Pro Tip: If you are prone to kidney stones, ask your clinician whether pairing oxalate containing foods with calcium containing foods at the same meal makes sense for you, because calcium can bind oxalate in the gut for some people. Do not start supplements without medical advice.

Before vs after, how to keep smoothies without overloading oxalates

The video’s tone is not “never eat plants.” It is closer to “stop treating daily raw spinach smoothies as a health law.”

A useful way to apply this is to compare options.

Option A vs Option B (a realistic swap)

Option A: The classic daily green smoothie

Large handfuls of raw spinach or Swiss chard blended daily.

Often paired with other oxalate sources (for example, almonds or almond butter, cacao, some berries).

Easy to over consume because it drinks fast.

Option B: A lower oxalate, kidney friendlier smoothie pattern

Base of banana and dairy or another protein source, then small amounts of greens or rotate to lower oxalate greens.

Use cooked, steamed, soaked, or fermented greens if you want that flavor and micronutrient profile.

Treat greens as an accent, not the bulk of the drink.

This is the “middle path” the video keeps returning to.

Cooking and fermenting, the practical fix emphasized in the video

One of the most actionable points is preparation.

The discussion suggests that raw green leafy vegetables have the highest concentrations in the context of smoothie habits, and recommends methods that may reduce oxalate exposure, such as steaming, soaking, cooking, and fermenting.

A short caution is important here: not all cooking methods reduce oxalates equally, and reductions depend on the food and whether cooking water is discarded. Still, research suggests boiling certain vegetables can reduce soluble oxalate content. For example, a study in the Journal of Agricultural and Food Chemistry found cooking methods changed oxalate levels in vegetables like spinach and Swiss chard, with boiling often reducing soluble oxalate more than steaming: Effect of cooking on oxalate contentTrusted Source.

How to build a “safer by default” smoothie routine

If you want the convenience of smoothies, the video’s message can be translated into a simple routine.

Stop making raw spinach the daily default. Rotate ingredients so you are not repeatedly dosing the same high oxalate greens every morning.

Treat green juices and cleanses as occasional, not everyday. The cases discussed often involve repeated, heavy intake. A novelty smoothie is different from a daily cleanse.

Use preparation methods that may lower oxalates. If you love spinach, consider cooked spinach in meals rather than raw spinach in a blender, and consider fermenting vegetables if you already make fermented foods.

Support kidney basics that get ignored in wellness culture. Hydration and balanced mineral intake matter. The National Kidney FoundationTrusted Source highlights hydration as a foundational stone prevention strategy.

If you have symptoms or risk factors, do not guess. A clinician can evaluate kidney function, urine studies for stones, and whether dietary oxalate restriction is appropriate for you.

»MORE: If you want a practical tracking sheet, create a one week “smoothie log” listing greens used, portion size, powders, and hydration. Bring it to a clinician or dietitian visit to make the conversation specific.

Greens powders and “clean” supplements, the concentration problem

A second theme in the video is that powders can amplify the same issue as smoothies, concentration.

The argument is straightforward: when you dehydrate and powder greens, you can end up with a large amount of plant material in a small scoop. If the original plant is high in oxalates, the powder can be a concentrated source. The video’s stance is generally to avoid greens drinks for this reason.

It also raises another concern: heavy metals (arsenic, cadmium, lead) showing up in some plant based powders, and mentions that pea protein and rice protein can have similar issues. This is not purely speculative, independent testing has found heavy metals in some protein powders and greens powders, although levels vary widely by product and batch.

For background on why contaminants are monitored, the FDA’s guidance on toxic elementsTrusted Source explains how metals can enter the food supply.

What to do if you still want a powder

Not everyone can cook daily, and some people rely on supplements.

If you use powders, the most practical harm reduction steps are about transparency and moderation.

Look for third party testing. Choose products that publish certificates of analysis or use reputable independent testing programs.

Avoid stacking concentrates. A greens powder plus daily spinach smoothie plus almond butter plus cacao can quietly become a high oxalate pattern.

Use moderation rather than daily dependence. The video’s suggestion is essentially “not every single day.” If you notice symptoms, consider pausing and discussing with a professional.

Expert Q&A box

Q: Do green smoothies cause kidney failure for most people?

A: Most people who drink occasional smoothies will not develop kidney failure. The concern highlighted here is repeated, heavy intake of high oxalate greens, especially in people with risk factors like prior gut surgery, kidney stone history, or reduced kidney function.

If you are unsure where you fit, a clinician can check kidney function (blood and urine tests) and help you decide whether limiting high oxalate foods is appropriate.

Jordan Lee, RD (Registered Dietitian), renal nutrition focus

Q: Is it safer to cook greens instead of blending them raw?

A: Cooking can reduce soluble oxalates in some vegetables, especially when boiled and the water is discarded, although the effect depends on the specific food and method. If you are at risk for kidney stones, it is reasonable to ask a dietitian about preparation methods and portion sizes rather than assuming raw is always best.

Amina Patel, MD, Internal Medicine

Key Takeaways

Green smoothies are not automatically harmless, because blending and juicing can concentrate oxalate rich greens like spinach, Swiss chard, and kale.

Case reports link extreme green smoothie patterns to oxalate nephropathy, including biopsy confirmed calcium oxalate crystals and, in rare cases, progression to dialysis.

Susceptibility matters, risk may be higher with kidney stone history, CKD, prior GI bypass, recent prolonged antibiotics, dehydration, or cleanse style intake.

A practical middle ground is available, rotate ingredients, avoid daily raw spinach smoothies, and consider steaming, cooking, soaking, or fermenting greens to lower oxalate exposure.