Both magnesium glycinate and magnesium citrate are considered well-absorbed forms of magnesium, and neither has been proven to be universally superior for absorption. The biggest differences between them are related to digestive effects and how they are commonly used.
When comparing magnesium supplements, many people focus on one question: "Which form absorbs best?" The answer is more complicated than simply choosing the form with the highest number on the label.
Magnesium supplements do not enter the body as free magnesium metal. Instead, magnesium is provided as part of a compound that must dissolve in the digestive tract before the mineral can be absorbed. The compound attached to magnesium can influence its solubility, the amount of elemental magnesium provided, and its bioavailability[i].
Magnesium citrate has been shown in human studies to have better absorption than magnesium oxide, which is one reason it is often considered a preferred supplemental form[ii]. Magnesium glycinate, also called magnesium bisglycinate, has also demonstrated good absorption compared with some less bioavailable forms[iii].
However, there is not enough evidence to say that magnesium glycinate absorbs better than magnesium citrate, or vice versa. The better question is: "Which form fits my individual needs?"
Magnesium Absorption: Why the Form Matters
The form of magnesium matters because the compound attached to magnesium can influence solubility, elemental magnesium content, and digestive tolerance.
A magnesium supplement is not made entirely of magnesium. For example, magnesium glycinate contains magnesium attached to the amino acid glycine, while magnesium citrate contains magnesium attached to citric acid.
The entire compound is weighed when a supplement is manufactured, but the amount that matters nutritionally is the elemental magnesium content, which refers to the actual amount of magnesium mineral provided[iv].
This is why two bottles can show very different ingredient weights while providing similar amounts of magnesium. A product containing 1,000 mg of a magnesium compound does not necessarily provide 1,000 mg of magnesium.
It’s important to note, the body only uses the elemental magnesium portion.
Which Magnesium Is Gentler on the Stomach?
Magnesium glycinate is generally considered a gentler form of magnesium because it has demonstrated good gastrointestinal tolerability, while magnesium citrate is commonly used for its osmotic laxative effect and ability to draw water into the intestines[v] .
One of the biggest reasons people stop taking magnesium supplements is due to digestive discomfort. Certain forms of magnesium can draw water into the intestines, which may lead to softer stools or diarrhea, especially at higher supplemental doses15.
This effect is not always negative. For someone dealing with occasional constipation, it may be helpful. For someone taking magnesium daily for general nutritional support, sleep, or muscle function, frequent loose stools may be undesirable.
Magnesium glycinate is often chosen by people who want a magnesium supplement without a strong stomach effect. While direct head-to-head trials comparing every magnesium form are limited, clinical experience and available research suggest amino acid-bound forms such as magnesium bisglycinate are generally well tolerated7.
Digestive Tolerance Comparison
|
Feature |
Magnesium Glycinate |
Magnesium Citrate |
|
Daily use |
Common choice |
Common choice |
|
Digestive effect |
Usually mild |
More likely to loosen stools |
|
Constipation support |
Limited |
Commonly used |
|
Sensitive stomach |
Often preferred |
May not be ideal at higher doses |
Which Magnesium is Best for Sleep?
Magnesium glycinate is a popular choice for nighttime use, but current evidence does not prove that it is superior to magnesium citrate specifically for sleep.
Magnesium plays an important role in normal nervous system function, and inadequate magnesium intake has been associated with poorer sleep quality in some studies[vi].
Because magnesium helps regulate normal nerve signaling and muscle function, researchers have investigated whether supplementation may support healthier sleep patterns. One recent randomized controlled trial found that magnesium bisglycinate supplementation produced a modest improvement in insomnia symptoms among adults reporting poor sleep quality17.
However, this does not mean magnesium glycinate is a guaranteed sleep solution, as the study was relatively short, and the improvement was modest. More research is needed to determine whether magnesium glycinate is better than other well-absorbed forms, including magnesium citrate.
So why do many people choose magnesium glycinate before bed?
Usually because:
· It is gentle on digestion.
· It does not typically have a strong laxative effect.
· It is associated with relaxation because magnesium supports normal nervous system function.
It is also important to understand that the glycine attached to magnesium glycinate is present in much smaller amounts than the doses of glycine used in separate sleep studies. Human studies investigating glycine and sleep have typically used approximately 3 grams of free glycine before bedtime, which is substantially higher than the amount of glycine supplied as part of a typical magnesium glycinate supplement[vii]. Therefore, magnesium glycinate should not automatically be assumed to provide the same sleep effects as taking higher-dose glycine alone.
The Best Magnesium for Constipation
Magnesium citrate is one of the most commonly used magnesium forms for occasional constipation because it pulls water into the intestines, which can help soften stool and encourage bowel movements[viii].
Constipation is not usually caused by a lack of magnesium alone. However, certain magnesium compounds have an osmotic effect, meaning they increase water content inside the intestines, which can make stool softer and easier to pass.
Magnesium citrate is widely used for this purpose and is available in both supplement and laxative preparations. This is also why magnesium citrate may not be the first choice for someone who wants magnesium supplementation without digestive changes.
For those individuals, magnesium glycinate may be a better fit.
Constipation Comparison
|
Goal |
Often Preferred Form |
|
Occasional constipation |
Magnesium citrate |
|
Daily magnesium support |
Glycinate or citrate depending on tolerance |
|
Sensitive digestion |
Often glycinate |
|
Avoiding loose stools |
Often glycinate |
Magnesium for Muscle Function and Cramps
Magnesium is essential for normal muscle function, but research does not show that magnesium supplements consistently eliminate muscle cramps in everyone.
Magnesium plays an important role in normal muscle contraction and relaxation by helping regulate calcium and potassium movement within muscle cells. When magnesium levels are inadequate, normal muscle function can be affected[ix].
This has led many people to use magnesium supplements for muscle cramps. However, the research is more complicated. This in no way means magnesium is unimportant for muscles.
Magnesium remains an essential mineral involved in:
· normal muscle contraction
· nerve signaling
· energy metabolism
· electrolyte balance[x].
The key point is that correcting inadequate magnesium intake is different from expecting magnesium supplements to solve every type of muscle cramp.
Magnesium for Exercise Recovery
Magnesium supports normal energy production, muscle function, and electrolyte balance, but research on whether magnesium supplements improve athletic performance or recovery is mixed.
Magnesium is involved in hundreds of biochemical reactions related to energy metabolism and muscle function[xi].
Athletes with low magnesium intake may be more likely to benefit from correcting an inadequate intake. However, among people who already consume enough magnesium, supplementation does not consistently improve exercise performance or recovery.
A systematic review of magnesium supplementation and physical performance found that benefits were most likely in individuals with low magnesium status rather than healthy individuals with adequate intake[xii].
For active individuals, magnesium is best viewed as a foundational nutrient rather than a performance enhancer. A balanced diet, adequate protein intake, resistance training, hydration, and proper recovery remain the primary drivers of muscle adaptation.
PART 3
Can You Take Magnesium Glycinate and Citrate Together?
Magnesium glycinate and magnesium citrate are complimentary mineral forms, so they can be taken together. Remember, the main factor that determines magnesium intake is the amount of elemental magnesium provided, not simply the number of magnesium forms included in a supplement15.
Different magnesium compounds have different chemical structures, which can influence factors such as solubility, absorption characteristics, and digestive tolerance20. For some people, combining forms may make sense based on their individual goals.
For example, someone may choose magnesium glycinate in the evening because it is commonly selected for gentle daily use and nighttime routines. Another person may choose magnesium citrate because they want magnesium support while also benefiting from its bowel-regulating effects.
A formula containing multiple magnesium forms does not automatically guarantee better results than a single-form magnesium supplement. However, choosing different research-studied forms may provide different advantages because the compound attached to magnesium can influence factors such as absorption, transport, and how the body utilizes magnesium.
For example, magnesium L-threonate has been studied for its ability to increase magnesium levels in the brain and has demonstrated potential cognitive benefits in clinical research. It is currently the only magnesium form with published human research specifically investigating its ability to raise magnesium concentrations in the brain[xiii].
Magnesium taurate has also been studied because taurine plays important roles in cardiovascular function, and early research suggests magnesium taurate may have potential benefits related to heart health[xiv].
The most important factors are the amount of elemental magnesium provided, the quality of the ingredients, and whether the person can consistently tolerate and use the supplement. More magnesium is also not always better.
Higher supplemental intakes of magnesium can increase the likelihood of gastrointestinal side effects, including diarrhea, nausea, and abdominal discomfort. The tolerable upper intake level for supplemental magnesium was originally established based largely on the risk of diarrhea observed with higher supplemental doses[xv].
The Problem with Magnesium Oxide
Magnesium oxide is one of the most commonly used forms of supplemental magnesium. Unlike magnesium glycinate, where magnesium is bound to the amino acid glycine, magnesium oxide is magnesium combined with oxygen.
One reason magnesium oxide is popular is because it contains a high percentage of elemental magnesium by weight. This allows manufacturers to provide a relatively large amount of magnesium in a small capsule. However, the amount of magnesium listed on a label is only one part of the story.
The body must first dissolve the magnesium compound before absorption can occur. Research comparing magnesium oxide with other magnesium forms has found that magnesium oxide generally has lower bioavailability than magnesium citrate and several other organic magnesium salts[xvi].
This doesn’t mean magnesium oxide is useless, as it has legitimate uses, including applications where a stronger bowel effect is desired. Its lower absorption profile may partly explain why it is more likely to produce a laxative effect in some individuals[xvii].
For someone looking for a daily magnesium supplement focused on absorption and nutritional replenishment, forms other than magnesium oxide should be considered. The right choice ultimately depends on the end goal.
Why the Magnesium Number on the Label Can Be Misleading
When comparing magnesium supplements, many consumers naturally assume the product with the highest magnesium number must be the best choice. However, the number alone does not tell the whole story.
The magnesium listed on the label represents elemental magnesium, but it does not indicate how well that form is absorbed or how the body may use it.
This is where magnesium oxide becomes an important example. Because magnesium oxide contains a high percentage of elemental magnesium and is inexpensive, it allows manufacturers to achieve a larger magnesium number on the label while keeping raw material costs lower.
Many formulas combine magnesium oxide with smaller amounts of more expensive magnesium forms to increase the total magnesium amount displayed on the label. Consumers should understand an important difference:
A higher magnesium number does not equate to a better magnesium formula.
When evaluating a supplement, look beyond the front label and consider:
- Which magnesium forms are included?
- Are those forms supported by research?
- How much of each form is actually provided?
- Does the formula match your specific needs?
A thoughtfully designed magnesium supplement is not about achieving the largest number possible. It is about choosing forms that provide meaningful magnesium support in a way the body can tolerate and use consistently.
Who Should Choose Magnesium Glycinate?
Magnesium glycinate may be a good choice for people who:
· want daily magnesium support
· prefer a magnesium form that is generally gentle on digestion
· are adding magnesium to an evening routine
· do not want a strong laxative effect
Magnesium glycinate contains magnesium attached to glycine, an amino acid involved in normal nervous system function.
Glycine itself has been studied for its potential role in sleep quality. However, the amount of glycine supplied by magnesium glycinate supplements is usually much lower than the doses used in separate glycine sleep studies[xviii]. This distinction matters.
Magnesium glycinate should not be viewed as a sleep medication. Rather, it is a magnesium form that many people choose because of its combination of magnesium and a generally well-tolerated amino acid.
Who Should Choose Magnesium Citrate?
Magnesium citrate may be a good choice for people who:
· want magnesium supplementation with occasional constipation support
· tolerate its digestive effects well
· are looking for a magnesium form with good absorption characteristics
Magnesium citrate is commonly used because the citrate molecule helps maintain magnesium solubility, which may support absorption compared with some other forms such as magnesium oxide13.
However, the same digestive effect that makes magnesium citrate useful for constipation may not be desirable for everyone. Someone looking for daily magnesium support without digestive effects may prefer another form.
How to Choose a Magnesium Supplement
Choosing a magnesium supplement comes down to understanding your goals and selecting a form that fits your needs. Here’s what to look for:
1. Choose the Form Based on Your Goal
Different magnesium forms may have different characteristics, which is why the best choice depends on what you are looking for.
Sleep and relaxation routines
Magnesium glycinate is commonly chosen by people looking for a gentle magnesium option as part of an evening routine.
Occasional constipation support
Magnesium citrate may be preferred because of its ability to draw water into the intestines and support bowel movements.
General magnesium support
Several magnesium forms may be appropriate depending on personal preference, digestive tolerance, and individual needs.
2. Consider Digestive Tolerance
The best magnesium supplement is the one someone can take consistently.
Some people tolerate magnesium citrate well, while others may prefer magnesium glycinate because it is often considered gentler on digestion.
Individual response matters.
3. Consider Multi-Form Magnesium Formulas
Some magnesium supplements combine several forms. Different magnesium compounds are attached to different molecules, which may influence characteristics such as absorption, transport, and digestive tolerance.
A well-designed formula should focus on selecting appropriate magnesium forms in meaningful amounts rather than simply adding more ingredients.
Common Magnesium Myths
Myth 1: The Most Expensive Magnesium Is Always the Best
Not necessarily. Price alone does not determine the quality or effectiveness of a magnesium supplement. A higher-priced product may contain different ingredients or a more complex formulation, but the important questions are:
· How much elemental magnesium does it provide?
· What form of magnesium is included?
· Does it fit your personal goal?
· Can you tolerate it?
Myth 2: Magnesium Glycinate is Always the Best Form
Magnesium glycinate is a popular form, but it is not automatically the best choice for everyone.
Some people prefer glycinate because it is gentle and well tolerated. Others may choose citrate because of its bowel-supporting effects.
The best magnesium form depends on the individual.
Myth 3: How Much Magnesium Should You Take?
The body regulates magnesium balance through absorption, storage, and excretion. Higher supplemental amounts of magnesium may increase the likelihood of gastrointestinal side effects, including diarrhea and abdominal discomfort, particularly in individuals who are more sensitive to magnesium supplementation[xix].
The tolerable upper intake level for supplemental magnesium has been set at 350 mg per day for adults by the National Academies, based primarily on the risk of gastrointestinal effects from higher supplemental doses rather than concerns about magnesium toxicity in healthy individuals[xx].
Some evidence suggests that splitting larger amounts of magnesium into smaller doses may improve absorption and reduce digestive side effects compared with taking a large amount all at once. For this reason, many magnesium supplements provide approximately 250 mg of elemental magnesium per serving, although individual absorption and tolerance can vary[xxi].
The goal with magnesium supplementation is not to take the highest dose possible, but instead to provide an appropriate amount that fits your needs and that your body can tolerate consistently.
Frequently Asked Questions
Is magnesium glycinate better than magnesium citrate?
Neither form is universally better. Magnesium glycinate is often chosen for gentle daily use and nighttime routines, while magnesium citrate is commonly selected by people who also want occasional constipation support.
Which magnesium is best for sleep?
Magnesium glycinate is commonly preferred for nighttime supplementation because it is generally well tolerated and contains glycine. However, magnesium is not a sleep medication, and individual responses vary.
Which magnesium is best for constipation?
Magnesium citrate is commonly used for occasional constipation because it draws water into the intestines, which can help soften stool and support bowel movements.
Can I take magnesium glycinate and citrate together?
Yes. Different magnesium forms can be combined. The most important considerations are the total elemental magnesium amount, individual tolerance, and personal goals.
How much magnesium should I take daily?
Magnesium needs vary depending on age, sex, diet, and individual factors. Adult dietary recommendations generally range from approximately 310–420 mg per day from food and supplements combined.
Does magnesium glycinate cause diarrhea?
Magnesium glycinate is generally considered one of the gentler magnesium forms, although any magnesium supplement can cause digestive effects in some people, especially at higher doses.
Does magnesium citrate help with sleep?
Magnesium citrate is mainly used for magnesium supplementation and digestive support. While magnesium plays a role in normal nervous system function, citrate is not specifically considered a sleep-focused magnesium form.
Is magnesium oxide a good form of magnesium?
Magnesium oxide provides magnesium and has legitimate uses, including bowel-related applications. However, other forms are more preferred by people looking for a daily magnesium supplement with different absorption characteristics.
The Bottom Line
There is no universally “best” magnesium.
The best choice depends on:
· personal goals
· digestive tolerance
· lifestyle
· individual needs
Magnesium glycinate is commonly chosen for:
· gentle daily magnesium support
· nighttime routines
· people who prefer a lower digestive impact
Magnesium citrate is commonly chosen for:
· well-absorbed magnesium support
· people who also want occasional constipation support
· those who tolerate its digestive effects
The best magnesium supplement is the one that provides an appropriate amount of elemental magnesium, uses a form that fits your goals, and is something you can consistently take.
If you missed the first part on magnesium, click this link click here.
About the Author: Brad King, MS, MFS, is an award-winning nutritional researcher, Canadian Sports Nutrition Hall of Fame inductee, and the author of 13 books, including the international bestsellers Fat Wars, Beer Belly Blues, and Dirty Diets. His work focuses on translating complex scientific research into practical, easy-to-understand health information.
Medical Disclaimer: This article is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before starting any new supplement, especially if you have a medical condition or take prescription medications.
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