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Which Type Of Magnesium Is The Most Absorbed By The Body?

Maintaining adequate levels of magnesium is important for overall health.

Magnesium plays a role in just about every important function in the body—energy production1, DNA protection, bone and heart health2, nerve signaling, muscle relaxation3 and control, stress management, mood, and more.

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Whether you are looking to boost your magnesium intake or you want to reap some of the many benefits (promoting restful sleep and PMS cramp relief, to name a few), you may be considering a magnesium supplement.

Since magnesium's absorption and benefits vary widely depending on its form, you need to make sure you're picking the one that's best for your needs.

Forms of magnesium

While there are many magnesium-rich foods, like nuts, beans, seeds, dark leafy greens, and whole grains, it can be difficult to get the appropriate levels through food alone.

In fact, almost 50% of the U.S. population doesn't get enough magnesium4 through their diet alone, so it is often taken through supplementation, either orally, transdermally (through the skin), and even through an IV.

Magnesium supplements are available in many forms, some of the most common being oxide, sulfate, glycinate, citrate, chloride, aspartate, and lactate.

Each form has different bioavailability, intended uses, and side effects, so let's walk through them.

Bioavailability of different magnesium forms

The most bioavailable (aka absorbable) forms of magnesium are bound to other compounds.

As renowned integrative physician Robert Rountree, M.D., explains, "Magnesium absorbs water. So when you take straight-up magnesium, like magnesium oxide, it forms these clusters of water, and that basically hurries things along in the gut."

That means these forms of magnesium promote a laxative effect but aren't really being absorbed into the bloodstream.  

Instead, look for a chelated form. "Chelate means 'claw,' and it simply means the magnesium is bound to an organic compound that basically helps ferry it across the lining of the gut," Rountree explains.

He recommends magnesium glycinate, which is bound to the amino acid glycine and is available in capsule or tablet form. 

Research has found that magnesium glycinate is one of the most absorbable forms, along with citrate, chloride, lactate, and aspartate5.

It is also important to note that zinc and calcium can reduce magnesium's absorption6, so be mindful of what you take it with.

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Magnesium glycinate versus magnesium citrate

Magnesium glycinate and citrate are two of the most common and absorbable forms; however, they aren't necessarily equal. Which one you choose depends on what you are looking to target. 

Magnesium citrate has a laxative effect, so it is typically used to help gut issues and constipation.

Magnesium glycinate, also known as bisglycinate or diglycinate, promotes relaxation7 and is typically recommended for sleep.

As Jolene Brighten, N.D., a naturopathic doctor put it, "Magnesium glycinate is highly absorbable, doesn't cause diarrhea like the citrate form can, and has a calming effect."

Can you take too much magnesium?

The tolerable upper intake levels for magnesium8 supplementation is 350 mg for adults, which is determined by the amount at which supplements cause mild diarrhea or gastric cramps in any individual.

Some individuals can tolerate much higher doses, though.  

Hypermagnesemia9, or magnesium overdose, is rare, but it is important to note that some health conditions can increase risk, especially those with impaired kidney function. 

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The takeaway

Which type of magnesium supplement you take will depend on your desired goal.

If you are concerned about magnesium deficiency or looking to reap the sleep and relaxation benefits of magnesium, you'll want the glycinate form.

Magnesium glycinate is one of the most absorbable forms of magnesium and has fewer GI side effects than other forms.

If you are taking magnesium to address constipation and gut issues, the citrate form will be a better fit.

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.
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Natalie Butler, RDN, LD
Natalie Butler, RDN, LD
Registered Dietitian Nutritionist

Natalie is a registered dietitian nutritionist with a passion to help others live their best life through food, fitness, safer beauty and a healthy lifestyle. She has expertise with a variety of diets and diseases and believes that there is no one-size-fits-all approach for health. Natalie consults for various organizations, like Apple, Inc., healthline.com, Head Health, Inc., and others, providing medical review, recipe and video creation, program development and delivery, seminars, and other services. She has also advocated for personalized functional nutrition and nutrigenomics-based lifestyle changes through her private practice Nutrition By Natalie since 2007. Natalie graduated from Stephen F. Austin State University with a Bachelor of Science in Food, Nutrition and Dietetics, and went on to pursue her graduate dietetic internship to become an RDN through Marywood University in Pennsylvania.

Natalie loves spending time with her husband and three children in the kitchen, garden and in nature. She is a foodie at heart and loves most cuisines, but especially spicy Indian and Thai.