Title: Magnesium & Kidney Stones - The 411 over an image of magnesium rich foods like nuts, whole grains, broccoli and avocado

Magnesium & Kidney Stones: The 411

Magnesium & kidney stones is a hot topic. Should people with kidney stones take magnesium? Will magnesium help everyone with kidney stones? Read on to learn everything you need to know about magnesium & kidney stones!

Magnesium 101

What is magnesium in the first place? Magnesium is a mineral found all over our bodies, but mostly in our bones and organs. (1)

Magnesium is important for many different body functions. It is used to make proteins, help muscles and nerves function normally, and control blood sugar and blood pressure. Magnesium is also important for bone health and to make energy from food. (1)

How Much Magnesium Do We Need?

The amount of magnesium you need is different based on your age and sex. (1)

  • Adult males: 410-420mg of magnesium each day
  • Adult females: 310-320mg of magnesium per day
  • People who are pregnant: 350-360mg of magnesium per day
  • People who are breastfeeding: 310-320mg of magnesium per day

Only about 50% of people in the United States are eating enough magnesium. (2) However, most people are getting enough magnesium from both food and magnesium in vitamins combined.

Foods High in Magnesium

We get most of the magnesium we need through healthy foods! Here are some foods high in magnesium:

  • Nuts
  • Seeds
  • Whole grains like whole grain bread, brown rice, whole grain pasta, quinoa or barley
  • Green leafy vegetables like spinach, Swiss chard, kale or collard greens
  • Beans, lentils and peas
  • Fortified cereals
Images of high magnesium foods that may be good for calcium oxalate kidney stones: green leafy vegetables, whole grains, beans, lentils, nuts and fortified cereals

Is Magnesium Good For Kidney Stones?

Probably! But, only for people with calcium oxalate kidney stones. And, supplements aren’t necessarily the best way to get magnesium for stone formers. Let’s cover what we DO know.

We know that people who have kidney stones tend to have lower magnesium in their blood, compared to people who do not have kidney stones. (3) (4)

At a molecular level, magnesium can inhibit calcium oxalate kidney stones. Magnesium binds with oxalate, making oxalate less likely to bind with calcium and form a kidney stone!

Magnesium can bind with oxalate both in the intestine and in urine; both are a good thing! When magnesium binds with oxalate in the intestine, oxalate absorption is reduced, ultimately reducing oxalate in urine. If magnesium binds with oxalate in urine, oxalate is stopped from binding with calcium and making a kidney stone.

It is important to know that magnesium will not dissolve kidney stones that have already formed. But, it could help stop more oxalate kidney stones from forming and stop them from getting bigger.

There is no reason to suspect that magnesium will cause kidney stones.

Since magnesium does all of these wonderful things, people with kidney stones should take magnesium, right? As usual, nutrition isn’t that straightforward. Let’s see what the research shows us.

Magnesium Supplements for Kidney Stones

Despite all the good things magnesium can do for kidney stones at a molecular level, research to see if magnesium supplements prevent kidney stones has not been promising. (5)

Most studies in humans have found that magnesium supplements do not prevent kidney stones. (6) (7) However, these trials could have had disappointing results because everyone was given magnesium, not just people with low magnesium. Or, perhaps the dose of magnesium wasn’t high enough. There are some promising studies done in animals. (8)

Ultimately, we need more research to know if magnesium supplements are good for kidney stones. We need more data to know who magnesium supplements might help, and how much magnesium is good for kidney stone prevention.

Types of Magnesium Supplements

Magnesium Citrate & Kidney Stones

Magnesium citrate is probably the most common magnesium supplement recommended for kidney stones. It has the potential double benefit of magnesium AND citrate. Magnesium citrate usually comes in a pill form. It is one of the most well absorbed forms of magnesium.

Citrate is a well known, powerful inhibitor of kidney stones. Citrate makes it more difficult for molecules to bind and form kidney stones. Potassium citrate is the most common pharmaceutical form of of citrate for people with kidney stones.

There have been some promising studies that found magnesium citrate can reduce the risk of calcium oxalate kidney stones. However, it is difficult to know if the magnesium or citrate component was beneficial for kidney stone prevention. (9) Unless you have low levels of citrate on a 24-hour urine test, supplemental citrate is probably not going to help prevent kidney stones.

As a dietitian, I always prefer food over supplements or medication. You can get more citrate from simply eating plenty of fruits and vegetables. Also, eating the right amount of protein can help keep urine citrate levels in a healthy range.

Magnesium Chloride

Magnesium chloride is also a form of magnesium that is well absorbed. It is commonly used to treat low magnesium levels as well as digestive symptoms like heartburn, constipation or stomach upset.

Magnesium Oxide

Magnesium oxide is the active ingredient in Milk of Magnesia and usually comes in a powder or pill form. It is most commonly used for gastrointestinal problems like heartburn, constipation or stomach upset.

Magnesium from magnesium oxide supplements is not well absorbed. It is not the best choice to treat low levels of magnesium.

Read more about other types of magnesium supplements.

Side Effects of Magnesium Supplements

Diarrhea is a common side effect of magnesium supplements. This is not surprising, as magnesium is a common recommendation to help constipation!

Other common side effects of magnesium are:

  • Nausea or vomiting
  • Abnormal heart rate
  • Light headedness
  • Bloating, gas or upset stomach

If you do take a magnesium supplement for kidney stones, be very mindful of diarrhea. A lot of fluid is lost with diarrhea or loose stools. The most important thing you can do to prevent kidney stones is drink plenty of fluid to dilute your urine. If you are loosing fluid with diarrhea, this could cause dehydration, more concentrated urine, and a higher risk for kidney stones!

Magnesium Toxicity

If you take a very large dose of magnesium for a long time, you could develop magnesium toxicity.

Signs of magnesium toxicity include: (1)

  • Nausea
  • Vomiting
  • Diarrhea
  • Weakness
  • Shortness of breath

Magnesium from Food for Kidney Stones

Despite the discouraging results from magnesium supplement trials, there is promising research for a high magnesium diet! People who eat more high magnesium foods tend to have fewer kidney stones. (10)

Diets like the DASH or Mediterranean diet have been shown again and again to be good for people with kidney stones. (11) (12) These dietary patterns are high in magnesium. They have lots of high magnesium foods like green leafy vegetables, legumes, nuts, and whole grains.

Oxalate in High Magnesium Foods

You may notice that nearly all high magnesium foods are also high in oxalate. This may be frustrating if you are limiting oxalate. What is a kidney stone maker to do!?

It is important to remember that nutrition for kidney stones is much more than a low oxalate diet. In fact, no research has found a lower risk of kidney stones on a low oxalate diet. Even though a low oxalate diet can lower levels of urine oxalate. (13) (14) Because oxalate and magnesium tend to be in similar foods, a low oxalate diet is inevitably lower in magnesium. This may be one of the reasons why a low oxalate diet is not associated with a reduced risk of kidney stones. In fact, eating more magnesium may help reduce urine oxalate levels. (15)

Most importantly, know that there is no one “kidney stone diet” that works for everyone. Unfortunately, low oxalate diets are handed out like candy, despite the fact that not everyone with kidney stones needs to avoid oxalate. Nutrition must be personalized to your 24-hour urine test, as recommended by the American Urological Association. (16)

Ask your dietitian how to balance oxalate and magnesium in the foods you eat!

Should You Take a Magnesium Supplement for Kidney Stones?

Magnesium supplements for kidney stones are not routinely recommended by the American Urological Association. (16) However, a magnesium supplement might be helpful if you have low magnesium levels and calcium oxalate kidney stones.

If you have low levels of magnesium in your blood, ask your doctor about a magnesium supplement. Or, (even better!) add more magnesium rich foods to your diet.

How Much Magnesium Should You Take?

We don’t know how much magnesium is best for kidney stones. Ask your doctor or dietitian how much magnesium is right for you.

We do know that taking very high doses of magnesium can cause problems, such as diarrhea. More than 350mg of supplemental magnesium per day is not recommended. (1)

Watch Out for Diarrhea!

If you do start taking a magnesium supplement for kidney stones, monitor very carefully for diarrhea.

The last thing you want is to loose a ton of fluid, as this could make kidney stones worse.

Does Magnesium Dissolve Kidney Stones?

No. Magnesium will not dissolve kidney stones. But, if you have low magnesium levels and calcium oxalate kidney stones, a magnesium supplement might help prevent kidney stones.

It is important to remember low magnesium is unlikely to be the only cause of kidney stones. A magnesium supplement alone is probably not enough to prevent kidney stones. There is a lot more you can do! It is important to get a 24-hour urine test to come up with a prevention plan that addresses all possible causes of your kidney stones.

Image of kidneys with kidney stones; common causes of calcium oxalate kidney stones listed around image: too much urine calcium, not enough urine citrate, too much urine oxalate, low urine pH, not enough urine

How to Prevent Kidney Stones

Kidney stone prevention is different for everyone. There is no single kidney stone diet, supplement or medication that will help everyone.

A 24-hour urine test is critical for your doctor to know the cause of your kidney stones, and come up with a personalized prevention plan. If you haven’t had this test before, ask your doctor for one today! I have some talking points to have this conversation with your doctor.

To get more information about personalized kidney stone nutrition, check out Kidney Stone Nutrition School!

Happy Eating!

Melanie

6 thoughts on “Magnesium & Kidney Stones: The 411”

  1. I have had several kidney stones, my last being 2010. I had a bad UTI last month out of nowhere and I’ve never had one in past, I am a male 42 Years old. Well turns out I have two 22mm stones in left kidney and a 2 inch or 53mm stone in right kidney. They cut me and did get some from left kidney and I’m having a different surgeon do my right kidney as he specializes in large stones. I drink a ton of water but do use sugar-free Kool-Aid drops. My surgeon said it looked like a calcium oxalate stone from right kidney but he said left appears to be a 2 inch staghorn stone, assuming they are calcium oxalate stones is it okay to use the Kool aid drops on my water to help drink more?

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Jason! Thank you for sharing so much about your history. Kidney stones aren’t a reason to avoid sugar free products. I will say that nutrition needs to be individualized to your 24-hour urine test results. Knowing that you have calcium oxalate stones is good, but doesn’t really tell us what is causing them. That is where that 24-hour urine test comes in!

      1. Thanks Melanie, I’m waiting on urine analysis package to arrive so I can start the process and find out hopefully🤞 what is causing these. I have started a water pill for blood pressure but I’ve read that can help with stone formation as I’m assuming it helps keep everything flushed. Your website is very informative and appreciated by us unlucky stone formers.

        1. Melanie Betz MS, RD, CSR, CSG

          Fantastic! So glad you are getting that test. Some diuretics can help with stones – primarily by reducing urine calcium actually. I’m so glad you’ve found my information helpful. Please do let me know if you want my help figuring out what that urine test tells you about diet changes that could help stop stones for you!

  2. Melanie, I need your advice. I have had 7 kidney stones since 2004. They are usually to large to pass and need Lithotripsy. I enjoy one cup of coffee in the morning. I don’t want to add sugar. My stones are calcium oxalate. Stevie is loaded with oxalate. What do you know about MonkFruit.??? Does it have oxalate? Is it ok on the kidneys? Can you suggest something else to sweeten my coffee without sugar??? Look forward to hearing from you.

    1. Melanie Betz MS, RD, CSR, CSG

      Hi Madelyn! Steveia actually doesn’t have oxalate in it – it is removed during processing from the plant. I’m sure sure about the oxalate content of Monkfruit. Honestly, most any artificial sweetener is okay for people with kidney stones. I can’t know exactly what is best for you without reviewing yout 24-hour urine test results, other medical history and current eating patterns though! Hope that helps.

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