How To Take A Magnesium Supplement That Won't Mess With Your Gut 

mbg Contributor By Jessica Timmons
mbg Contributor
Jessica Timmons is a freelance writer whose work has appeared in Healthline, Pregnancy & Newborn, Modern Parents Messy Kids, and more.
Medical review by Marvin Singh, M.D.
Integrative Gastroenterologist
Dr. Marvin Singh is an Integrative Gastroenterologist in San Diego, California. He is trained and board certified in Internal Medicine and Gastroenterology/Hepatology.
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Name just about any important function in the body—the regulation of blood sugar, blood pressure, and nerve and muscle function, stress management, energy production, even the actual creation of protein, bone, and DNA—and magnesium plays a role.* Magnesium supplements also seem to help soothe menstrual cramps and sore muscles, treat migraines, promote calmness, and help you enjoy some quality zzz's.* But there's a catch. There are different forms of magnesium, and while they are generally safe to use, some of them can cause a rather unpleasant side effect: diarrhea.

Forms of magnesium.

While magnesium is naturally present in a number of foods, including dark leafy greens, whole grains, nuts and seeds, milk, yogurt, and legumes, it's estimated that 48% of the U.S. population doesn't consume enough of them to sufficiently draw recommended amounts of this critical nutrient. That's a problem since low levels of magnesium over the long term can put you at greater risk of a number of health conditions, including heart disease, high blood pressure, type 2 diabetes, and osteoporosis. That's where supplements come in.

The most common forms of magnesium supplements include citrate, oxide, glycinate, chloride, lactate, and malate. Different forms have different intended uses and side effects—and yeah, diarrhea is one of them.


Why does magnesium cause diarrhea?

The issue really boils down to too much unabsorbed magnesium, which attracts water from surrounding tissues in the intestine or colon and overstimulates the bowel. "In higher doses, magnesium can interfere with the smooth muscles of the intestines, causing stimulation of the gut or some relaxation/disruption of the normal peristalsis," explains double board-certified surgeon and author Kent Sasse, M.D. "The result is diarrhea and sometimes cramping pain."

The key to avoiding diarrhea is twofold. You need to ensure you're taking the right kind of magnesium for your needs and nailing the dosage so your body can absorb it completely. "In general, the higher the dose, the more likely a person is to experience diarrhea," says Sasse.

If you're taking oral supplements of magnesium forms like citrate, malate, glycinate, and oxide, it's important to follow recommended daily doses. According to the National institutes of Health, the tolerated upper intake level for supplemental magnesium is:

  • 65 mg for children ages 1 to 3
  • 110 mg for children ages 4 to 8
  • 350 mg for those ages 9 and above

Do all forms of magnesium trigger diarrhea?

Dosing aside, certain versions of magnesium supplements are also more likely to cause diarrhea than others. "Some forms of magnesium supplements, such as carbonate, chloride, gluconate, oxide, and citrate form salts that draw water into the gut, leading to diarrhea—an osmotic effect of the magnesium salt," explains Sasse.

Magnesium citrate is one of the most common forms, and research suggests it has the highest bioavailability (absorbability). But it has a natural laxative effect and is often used to treat constipation. The same is true of magnesium oxide—the main ingredient in milk of magnesia, an over-the-counter medication for constipation relief.


The deep and restorative sleep you've always dreamt about, featuring magnesium glycinate.*

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It's a good idea to try different forms of the supplement to find what works for you. "Some people may find different kinds of the supplement to be gentler," notes Sasse, "and it's worth experimenting since everyone is different."

If you're considering a magnesium supplement and you'd like to avoid the possibility of diarrhea, a chelated version like magnesium glycinate is the place to start.* It's a form of magnesium that's bound to an organic compound—in this case, glycine, an amino acid—making it easily absorbed in the body.* Magnesium glycinate has also been shown to promote calm, relaxation, and deeper sleep in early trials, making it a good pick for anyone who has trouble falling or staying asleep.*


The takeaway.

Boosting your body's intake of magnesium can pay off with better sleep, fewer migraines, and less stress, among other benefits. And while it's true that diarrhea can be an unpleasant side effect, you can minimize the chances with proper dosing and by opting for a form of magnesium that's gentler on the body, like magnesium glycinate.*


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