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!
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:
- 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
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.
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 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 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.
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!
If you take a very large dose of magnesium for a long time, you could develop magnesium toxicity.
Signs of magnesium toxicity include: (1)
- 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.
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.
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!