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Spinach & Kidney Stones: Does Spinach Cause Kidney Stones?

a bowl-ful spinach is on the table, spinach can cause kidney stones

Is it really possible that spinach – which contains many key nutrients and offers a plethora of health benefits – can also cause kidney stones?

Well, the short answer to this question: unfortunately, yes. Eating spinach (especially raw spinach) on a regular basis may cause you to develop kidney stones.

Who says that?  Scientific studies, medical doctors and also board-certified nutrition specialists say so… 

To explore how and why eating spinach contributes to kidney stone formation, please keep on reading. We will also find out who is at risk of developing kidney stones due to spinach consumption.

Spinach and Kidney Stones

Who would have thought that spinach, which is associated with various health benefits, can also give you kidney stones that are typically very painful?

Well, sometimes even healthy foods can cause some unexpected and somewhat shocking side effects. Though in general, these side effects occur when eaten in excess of that foods.

For example, who would have thought that broccoli may disrupt sleep, walnuts can cause heartburn or bananas can trigger headaches?

Spinach is one of these foods. Although spinach is rather healthy, it may nevertheless contribute to kidney stones.

Does this mean you should stop eating spinach or become worried about developing kidney stones whenever you eat spinach?

In fact, there are two important points to underline.

The first one is that spinach increases the risk of developing kidney stones, particularly when eaten raw and too much on a regular basis.

The second one is that eating spinach is risky especially for those who are genetically predisposed to kidney stone formation and for those who are already suffering from it.

So, if you don’t have a genetic susceptibility to kidney stones or do not suffer from painful kidney stones, then eating spinach especially cooked spinach shouldn’t make you concerned too much.

But, do not think that spinach is the only healthy food that is associated with kidney stones! There are others that would make you surprised for contributing to kidney stones such as parsley, beetroot tops, almonds, raspberries and so on.

Below, we will discover how and why eating spinach increases the risk of having kidney stones.

However, before that, it must be sensible to talk about kidney stones briefly. By doing so, we can better comprehend the association between spinach and kidney stones.


What is a Kidney Stone?

If you have ever experienced a kidney stone, you don’t need anyone to tell you what it is and how painful it can be. In general, the pain is unbearable.

According to Mayo Clinic’s definition; kidney stones are hard deposits made of minerals and salts that form inside your kidneys (1).

If the stone or hard deposit gets big enough to block the flow of urine, it leads to pain (2),(3).

As for what causes kidney stones; there are many potential causes. In general though, not drinking enough water, consuming too much salt, having a sedentary lifestyle, diet, obesity, certain supplements, medications and some medical conditions can be shown as the main causes of kidney stones (1),(3),(4),(5).

Calcium oxalate stones, uric acid stones, struvite stones and cystine stones are the four main types of kidney stones. Among them, calcium oxalate stone is by far the most common type of kidney stone (5),(6),(7).

Calcium oxalate kidney stones are associated with foods that are high in oxalate (8),(9). (If you are asking what oxalate is below you will find a detailed explanation of it)

It is important to note that spinach is one of the richest foods in oxalate (10),(11). In addition to spinach; soy products, almonds, potatoes, beets, dates, black tea and chocolate are also high in this naturally occurring molecule, namely oxalate.


Why is Spinach Associated With Kidney Stones?

Essentially, the answer to this question has been given just above: oxalate! Yes, eating spinach can increase your risk of developing kidney stones because it is very high in oxalate.

However, it is important to remember that eating spinach does increase the risk of only one type of kidney stone; that is indeed calcium oxalate kidney stone.

In other words, you wouldn’t develop uric acid stones, struvite stones or cystine stones due to spinach consumption.

It bears repeating; unless you are genetically prone to developing kidney stones or eat raw spinach too much on a regular basis, spinach is unlikely to give you kidney stones!

So, now we know that since spinach is rather high in oxalate, therefore, can bring about kidney stones in people who are prone to it.

What is oxalate? Is it a harmful substance? Why does it increase the risk of developing kidney stones?

Well, these all are relevant questions. So, let’s answer them one by one.


1- What is Oxalate

In the simplest term; oxalate is an organic compound/molecule that is found in a great number of plants (12),(13),(14). 

That is to say, not only spinach but also many other plants contain this naturally occurring compound. So, it is not too easy to avoid this compound entirely from your diet.

Apart from food sources though, your body itself can produce oxalate (13),(15).

Oxalate binds to some of the minerals such as calcium, magnesium and potassium in the body, hence forming some compounds (5),(13).


2- Why Does Oxalate Cause Kidney Stones?

Oxalate doesn’t necessarily cause kidney stones. In fact, in most cases, this molecule is expelled from the body in the stool or urine.

However, if there is too much oxalate in your kidneys and too little liquid, then oxalate can bind, for instance, with waste calcium, thus forming calcium oxalate kidney stones (16),(17).

That translates into the fact that if your oxalate consumption is too high and your liquid intake too little, then the excess oxalate can bind with calcium in your kidneys and cause oxalate calcium stones.

So, if you are prone to kidney stones or carry the risk of developing kidney stones due, for instance, to your medical condition, then you may need to limit the consumption of the foods that are high in oxalate, such as spinach…


3-  Is spinach Contain Too much Oxalate?

Thus far we have repeatedly said since spinach is very high in oxalate, eating spinach can increase the risk of developing oxalate calcium stone.

What is the recommended intake of oxalic acid? How do we understand spinach has too much oxalate in it?

In fact, there is no absolute number for how much oxalate a person should consume a day. It can vary from person to person.

According to WebMD; most people consume 200 to 300 mg of oxalic acid each day (10).

Yet, those who carry the risk of developing calcium oxalate kidney stones are usually advised to limit their oxalate consumption to 50 to 60 grams each day (10),(18),(19).

Given the fact that a half-cup of cooked spinach contains 750 milligrams of oxalate, we can say: yes, spinach has too much oxalate in it (10).

So, if you are prone to kidney stones or suffering kidney stones, eating spinach may not be ideal for you.


Should You Stop Eating Spinach for Causing Kidney Stones?

Talking with your health care provider or with your dietitian as to whether you should or shouldn’t stop eating spinach to prevent kidney stones is what you should do!!

Our recommendations are: 

  • If you have ever developed calcium oxalate kidney stones before, then limiting your spinach consumption is a wise decision to prevent it from happening again.

  •  If you have a medical condition that makes you susceptible to kidney stones, you may need to limit spinach and other foods that are high in oxalate.

  • If you are genetically disposed to kidney stones, then it is sensible for you not to consume too much oxalate.

  • Researchers discovered that boiling spinach can decrease the oxalate levels of spinach. So, consider boiling spinach to minimise the kidney stone risk caused by high oxalate in spinach (20),(21),(22).

  • If you have the risk of developing kidney stones, make sure you consume plenty of water each day. Water can prevent oxalate from binding to calcium, thus decreasing your risk of any type of kidney stones significantly (23),(24).

Note: Scientists are working hard to develop low-oxalate mutant spinach (25).

Do always talk to your health care provider before eliminating a healthy food from your diet due to a particular side effect of that food.


Bottom Line

Since spinach is renowned for its health benefits, it must be surprising for many people to hear that spinach can potentially cause kidney stones.

Well, as repeatedly mentioned above, if you are a healthy person who doesn’t have any risk of developing kidney stones, then eating spinach is very unlikely to give you calcium oxalate stones.

Moreover, if you drink plenty of water during the day, you can consume healthy spinach with peace in mind.

As for those who have the risk of developing kidney stones; In this case, yes spinach can increase your risk of developing kidney stones due to its extremely high oxalate level.

So what can you do?

If you want to continue consuming foods that are high in oxalate despite your high risk of kidney stones, please do talk to your nutritionist or health care provider. They will know what is best for you…



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