Magnesium Bisglycinate vs Magnesium Citrate: Which One Do You Need?
Magnesium bisglycinate and magnesium citrate are the two forms people compare most often. Both are absorbed well. The difference that matters in practice is not absorption. It is what each form does in the gut, and how much actual magnesium ends up in each capsule.
What each one is
Magnesium bisglycinate is magnesium bound to two molecules of the amino acid glycine. It is the same compound as magnesium glycinate, under a different name. We covered that naming confusion here.
Magnesium citrate is magnesium bound to citric acid.
Absorption is closer than the marketing suggests
According to the US National Institutes of Health, small studies have found that citrate is among the forms of magnesium with higher bioavailability than magnesium oxide and magnesium sulfate. The NIH fact sheet does not rate glycinate at all.
Bisglycinate is widely sold as the best absorbed form. We have not found strong head-to-head evidence that either form is absorbed meaningfully better than the other. Both sit in the well-absorbed group. Neither is the poorly absorbed option. That role belongs to oxide.
The real difference is the gut
Magnesium citrate draws water into the intestine. At normal supplement doses this is usually mild. At higher doses it loosens stools, and at much higher doses magnesium citrate is sold as an over-the-counter laxative.
Bisglycinate does not have that reputation. It is generally the gentler of the two on the digestive system.
That gives a simple way to choose:
If you want some help with regularity, citrate can do two jobs at once.
If your gut is sensitive, or you want a daily magnesium without that effect, bisglycinate is the safer pick.
How much magnesium is actually in the capsule
Neither form is mostly magnesium. Magnesium bisglycinate is roughly 14 percent magnesium by weight. Magnesium citrate is roughly 11 to 16 percent, depending on the exact citrate salt and how much water it holds.
That is why the large number on the front of a pack can mislead. A capsule with 105 mg of magnesium needs roughly 750 mg of magnesium bisglycinate to deliver it.
The figure to compare is elemental magnesium per serving. If a label does not state it, two products cannot be compared fairly.
How much you need, and the ceiling
The NIH recommended daily amount for adults is 310 to 420 mg of magnesium, depending on age and sex. That includes magnesium from food.
There is also an upper level of 350 mg a day for magnesium from supplements and medicines. Magnesium from food does not count toward it. Above that level, diarrhea becomes more likely, whichever form you take.
Magnesium bisglycinate products that passed the CuratedFit Standard
Source Naturals Magnesium Bis-Glycinate provides 200 mg of magnesium per two-tablet serving, from a single form.
Life Extension Magnesium Glycinate provides 105 mg of magnesium per capsule, also from a single form, with one to three capsules as the stated serving.
Neither product blends bisglycinate with a cheaper form under one undisclosed total. That is the label problem that most often makes magnesium products hard to evaluate.
The takeaway
Choose citrate if you want the gentle laxative effect. Choose bisglycinate if you do not. Then ignore the form names on the front and compare the elemental magnesium on the back.
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