Magnesium Glycinate vs Citrate: What the Research Says

If you’ve decided to supplement with magnesium (and given that roughly half of Americans don’t meet the RDA through diet, it’s a reasonable decision), your next question is probably: which form?

The two most popular options are magnesium glycinate and magnesium citrate. Both are well-absorbed, widely available, and affordable. But they’re not interchangeable — each has distinct properties that make it better suited for different goals.

Here’s what the research actually says about how they compare.

The Basics: What’s the Difference?

#

Magnesium glycinate (also called magnesium bisglycinate) is magnesium bound to the amino acid glycine. This chelated bond protects the magnesium from interacting with other compounds in the gut, which improves absorption and reduces GI side effects.

Magnesium citrate is magnesium bound to citric acid. It’s one of the most commonly used supplemental forms, partly because it’s inexpensive to produce and partly because citric acid itself enhances absorption.

Both forms deliver “elemental magnesium” — the actual Mg2+ ion your body uses. The difference is in the carrier molecule (glycine vs. citric acid), which affects how the supplement behaves in your body.

Absorption and Bioavailability

#

Both glycinate and citrate are well absorbed — dramatically better than the cheap magnesium oxide found in many pharmacy supplements.

A study published in the Journal of the American College of Nutrition found that magnesium citrate had significantly higher bioavailability than magnesium oxide. Other research comparing various organic magnesium salts (including glycinate and citrate) shows they perform similarly, with absorption rates roughly 3-4 times higher than oxide.

Direct head-to-head comparisons between glycinate and citrate are limited, but the available data suggests comparable absorption in the 25-30% range for both. The chelated structure of glycinate may provide a slight edge in certain conditions (like lower stomach acid), but the practical difference is modest.

Takeaway: Both are well absorbed. Don’t choose between them based on bioavailability alone — the difference isn’t significant enough to matter.

GI Tolerance: The Biggest Practical Difference

#

This is where glycinate has a clear advantage.

Magnesium citrate has an osmotic laxative effect. It draws water into the intestines, which softens stool and stimulates bowel movements. In fact, high-dose magnesium citrate is used as a bowel prep solution before colonoscopies. At standard supplemental doses (200-400mg), most people tolerate it fine, but those with sensitive stomachs, IBS, or a tendency toward loose stools may notice an effect.

Magnesium glycinate, by contrast, is one of the gentlest forms on the stomach. The chelated bond means less free magnesium interacting with the gut lining. Most people experience zero GI effects from glycinate, even at higher doses.

Takeaway: If you have a sensitive stomach or don’t want any risk of GI effects, glycinate is the safer choice. If you tend toward constipation, citrate’s mild laxative effect might actually be a benefit.

Use Cases: When to Choose Each

#

Choose Glycinate For:

#

• Sleep support — Glycine, the amino acid bound to the magnesium, has its own research-backed calming effects. A study in the Journal of Physiological Anthropology found that 3g of glycine before bed improved sleep quality and reduced daytime fatigue. You won’t get 3g of glycine from a standard magnesium glycinate dose, but you do get some.
• Anxiety and stress — The combination of magnesium (which modulates the HPA stress axis) and glycine (which has inhibitory neurotransmitter effects) makes glycinate a logical choice for anxious individuals.
• General daily supplementation — If you just want to correct a magnesium shortfall without thinking about side effects, glycinate is the most hassle-free option.
• Sensitive stomach — Anyone prone to GI issues should default to glycinate.

Choose Citrate For:

#

• Constipation — If you struggle with regularity, citrate’s osmotic effect is a genuine benefit. Many people use magnesium citrate specifically for this purpose.
• Powder format preference — Magnesium citrate dissolves well in water, which is why products like Natural Vitality CALM use it. If you prefer drinking your magnesium rather than swallowing pills, citrate is the practical choice.
• Budget — Citrate is generally cheaper than glycinate per serving.
• Higher doses — If you need a higher amount of elemental magnesium per serving, citrate formulations often deliver more per dose.

What About Other Forms?

#

For completeness, here’s where other common forms fit in:

• Magnesium L-threonate — The only form with research showing it crosses the blood-brain barrier. Best for cognitive support. More expensive and lower in elemental magnesium. Read more in our best magnesium supplements guide.
• Magnesium oxide — Poor bioavailability (roughly 4% absorption). The main reason it’s still sold is that it’s extremely cheap. Best avoided for supplementation; it’s primarily a laxative.
• Magnesium taurate — Some evidence for cardiovascular benefits. Less studied than glycinate or citrate. A reasonable option if heart health is your focus.
• Magnesium malate — Often recommended for energy production and muscle soreness. Reasonable bioavailability but limited comparative research.

Dosing Considerations

#

Regardless of the form you choose, the key number is elemental magnesium — the actual amount of Mg2+ you’re getting per serving.

• RDA: 310-420mg daily for adults (varies by age and sex)
• Typical dietary intake: 250-350mg from food
• Supplemental gap to fill: 100-300mg typically
• Tolerable upper limit from supplements: 350mg (per the IOM)

Be aware that a “500mg magnesium glycinate” capsule does not contain 500mg of elemental magnesium. The 500mg refers to the total compound weight (magnesium + glycine). The elemental magnesium might be only 100-120mg. Always check the Supplement Facts panel for the elemental amount.

Our Recommendations

#

For most people looking for a daily magnesium supplement, we recommend magnesium glycinate as the default. It’s well absorbed, gentle on the stomach, supports sleep and relaxation, and works for anyone.

If you specifically struggle with constipation, prefer a powder format, or are on a tight budget, magnesium citrate is a solid choice.

For specific product picks, see our full best magnesium supplements roundup. Our top glycinate pick is Doctor's Best Magnesium Glycinate and our top citrate/powder pick is Natural Vitality CALM.

Frequently Asked Questions

#

Which is better absorbed, glycinate or citrate?

Both have similar bioavailability (roughly 25-30%), far superior to magnesium oxide. The practical absorption difference between the two is small.

Can I take both glycinate and citrate together?

Yes. Some people take glycinate in the evening for sleep and citrate during the day. Just track your total elemental magnesium.

Which is best for sleep?

Magnesium glycinate, thanks to the calming effects of the glycine component.

Does citrate cause diarrhea?

At higher doses, it can. Citrate has an osmotic laxative effect. At standard supplemental doses, most people tolerate it fine.

Is glycinate good for anxiety?

Promising but not conclusive. Magnesium modulates the stress response, and glycine has calming effects, but more high-quality research is needed.