What Is Magnesium Glycinate?

Magnesium glycinate is magnesium bound to glycine, an amino acid. That pairing makes a supplement that's well absorbed and unusually gentle on the stomach, which is why it's become the go-to form for sleep, relaxation and everyday top-ups.

You'll also see it sold as magnesium bisglycinate. For practical purposes, they're the same thing. "Bis" just means each magnesium is attached to two glycine molecules, which is how glycinate supplements are made.

A note from me, Tom: I take magnesium on and off for roughly two-thirds of the year. The main difference I notice is waking up feeling more rested. That's one person's experience; the research is below.

What magnesium does in your body

Magnesium is a mineral your body needs for hundreds of chemical reactions. It supports muscle and nerve function, helps regulate blood sugar and blood pressure, and is needed to make protein, bone and DNA (NIH Office of Dietary Supplements).

Adults need about 310 to 320 mg a day for women and 400 to 420 mg for men, from food and supplements combined. Good food sources are leafy greens, nuts, seeds, beans and whole grains. According to the NIH, the diets of many people in the US provide less than these amounts.

What makes glycinate different

Every magnesium supplement is magnesium bonded to something else. What it's bonded to changes how much magnesium you get per capsule, how well it absorbs and what it does to your gut.

In glycinate, the magnesium is chelated, meaning it's held by the glycine in a ring-like structure. That has three practical effects:

1. It absorbs well. Glycinate belongs to the group of organic forms that absorb better than inorganic forms like magnesium oxide. It doesn't clearly beat citrate, the other popular well-absorbed form, but it's comfortably in the top tier.
2. It's gentle on the stomach. Most magnesium forms loosen your stools at higher doses, because unabsorbed magnesium pulls water into the bowel. Glycinate rarely does this, which is its biggest real advantage.
3. It's mostly glycine by weight. Only about 14% of magnesium glycinate is actual magnesium. That's why the elemental dose on the label matters so much (more on that below).

What it's used for

The glycine might add a small extra. Glycine has its own sleep research, using 3 g before bed. A typical 250 mg dose of magnesium as bisglycinate carries about 1.5 g of glycine, so roughly half that amount.

How much to take

Most people take 200 to 350 mg of elemental magnesium a day. Health authorities set the upper limit for magnesium from supplements at 350 mg a day for adults. Magnesium from food doesn't count toward that limit (NIH ODS).

Reading the label

This is where most people go wrong. Because glycine is heavy, a bottle that says "Magnesium Glycinate 1,000 mg" on the front may contain only about 140 mg of actual magnesium.

Ignore the front of the bottle. On the Supplement Facts panel, find the line that reads "Magnesium (as magnesium bisglycinate) ___ mg". That number is the elemental magnesium, and it's the one to dose by.

Also check for the word "buffered". Some products mix in cheaper magnesium oxide to fit more magnesium into each capsule, which makes them more likely to cause loose stools. Look for "fully reacted" or "100% chelated" if you want pure glycinate.

Glycinate vs other forms

Our full comparison of magnesium forms goes into each in detail.

Is it safe?

For healthy adults at up to 350 mg a day, yes. The most common side effect is loose stools, and glycinate causes it less often than other forms. In the largest sleep trial, 93% of participants reported no side effects at all.

A few cautions, from the NIH:

• Kidney disease: your kidneys clear extra magnesium. If they can't, it can build up. Don't take supplements without your doctor's approval.
• Some medications: magnesium can reduce absorption of certain antibiotics (tetracyclines and quinolones) and osteoporosis drugs (bisphosphonates). Take them at least two hours apart.
• Diuretics and acid-reflux drugs can change your magnesium levels. Ask your pharmacist.

If you're choosing a product, our magnesium glycinate for sleep guide has three picks with the elemental dose spelled out.

Questions people ask

Is magnesium glycinate the same as bisglycinate?

Yes, for practical purposes. Bisglycinate means each magnesium is bound to two glycine molecules, which is how glycinate supplements are made.

Is magnesium glycinate better than citrate?

For sleep and sensitive stomachs, usually yes. For absorption, they're about the same. Citrate is cheaper and has a mild laxative effect, which helps if you're constipated.

Can I take magnesium glycinate every day?

Yes, for most healthy adults, at up to 350 mg a day from supplements. If you have kidney disease or take regular medication, check with your doctor or pharmacist first.

When should I take magnesium glycinate?

Any time suits a general top-up. For sleep, take it 30 to 60 minutes before bed, which is what the main sleep trial did.

TD

Written by Tom D

Tom has trained in the gym for years and has taken 5 g of creatine every day for about a decade, with magnesium on and off for most of the year. Reading the research behind supplements started as a hobby; this site is where he writes it up. He isn't a doctor or dietitian, so every claim links to the study behind it.

Sources

1. NIH Office of Dietary Supplements, Magnesium fact sheet
2. Systematic review: bioavailability of magnesium food supplements (2021)
3. Schuster et al. 2025, Magnesium bisglycinate in adults reporting poor sleep
4. Yamadera et al. 2007, Glycine and sleep quality

We link to the original study wherever we can. Read how we grade evidence and choose products.