Magnesium glycinate and magnesium citrate are both well-absorbed forms of magnesium, but they behave differently once you take them. Glycinate is magnesium bound to the amino acid glycine and is generally gentler on the stomach. Citrate is magnesium bound to citric acid and is more likely to loosen the bowels, which is why it turns up in some products for occasional constipation. If you are weighing up a daily magnesium glycinate supplement against a citrate, this guide compares the two side by side so you can choose based on what you actually need.
The quick answer
- Choose magnesium glycinate if you have a sensitive stomach, want a gentle option for a daily routine, or prefer to take your magnesium in the evening.
- Choose magnesium citrate if you are happy with a mild laxative effect, want a lower cost per dose, or need a form that some people use for occasional constipation.
- Either way, the NHS says 400mg or less a day of magnesium from supplements is unlikely to cause harm, so check the elemental magnesium on the label rather than the compound weight.
What is magnesium glycinate?
Magnesium glycinate is a chelated form of magnesium, meaning the mineral is bound to an amino acid, in this case glycine. In supplements it is most often sold as magnesium bisglycinate, where each magnesium ion is attached to two glycine molecules. The two names are used interchangeably on labels, so look for either one alongside the amount of elemental magnesium per serving. For reference, our pure magnesium glycinate 600mg capsules list 72mg of elemental magnesium per capsule. For what it does in the body, see our guide to what magnesium glycinate does.
Because it is bound to an amino acid, some magnesium glycinate appears to be absorbed intact through a peptide transport route in the small intestine. In a small crossover trial in people who had part of their small intestine removed, the magnesium diglycinate study by Schuette and colleagues found that overall absorption was similar to magnesium oxide, but the glycinate form was better tolerated and absorbed better in the patients who absorbed oxide poorly.
What is magnesium citrate?
Magnesium citrate is magnesium combined with citric acid, the same acid found in citrus fruit. It dissolves readily in water, which is one reason it is a popular choice in powders and capsules. The NIH Office of Dietary Supplements notes that forms which dissolve well in liquid tend to be absorbed more completely, and that citrate, aspartate, lactate and chloride forms are generally more bioavailable than magnesium oxide and magnesium sulfate.
The trade-off is that any magnesium that is not absorbed stays in the gut and draws water in with it. That osmotic effect is why citrate can loosen stools, particularly at higher doses.
Magnesium glycinate vs bisglycinate: is there a difference?
In most supplements, no. Magnesium bisglycinate is the chemical name for magnesium bound to two glycine molecules, and "magnesium glycinate", "diglycinate" and "glycinate chelate" on a label usually mean the same compound. So when you compare bisglycinate with citrate, everything in this guide applies.
The difference worth checking is whether a product is buffered. Some glycinate products mix in magnesium oxide to raise the amount of magnesium per capsule. The label then lists magnesium oxide or says "buffered", and an elemental magnesium figure well above the 12% to 14% you would expect from glycinate alone is a sign. Part of the dose is then oxide, which the NIH lists among the less bioavailable forms. Our magnesium glycinate capsules contain magnesium glycinate only, at 12% elemental magnesium (72mg per 600mg capsule).
Magnesium glycinate vs citrate: full comparison table
Use this table to compare the two forms on the points that matter when you are choosing. The right-hand column translates each difference into what it means for you. On a phone, scroll the table sideways to see every column.
| Feature | Magnesium glycinate | Magnesium citrate | What it means for you |
|---|---|---|---|
| What it is | Magnesium bound to the amino acid glycine (a chelate) | Magnesium bound to citric acid (a salt) | Both are organic forms, so neither is the low-absorption oxide type. |
| Also labelled as | Magnesium bisglycinate, diglycinate, chelated magnesium (check it is not buffered with oxide) | Trimagnesium dicitrate | Match the label name to what you are comparing. |
| Elemental magnesium by weight (approx.) | Around 12% to 14% (ours: 12%) | Around 11% to 16% (varies with the citrate salt and its water content) | Read the elemental magnesium per serving, not the compound weight in mg. |
| Absorption | Well absorbed. Part may be taken up intact as a small peptide. | Well absorbed. More bioavailable than oxide in several studies. | No clear winner. Head-to-head human data on the two is limited. |
| Stomach tolerance | Generally gentle | More likely to cause loose stools, especially at higher doses | If you have had digestive upset with magnesium before, start with glycinate. |
| Laxative effect | Uncommon at sensible doses | Osmotic effect. Used in some over-the-counter products for occasional constipation. | Citrate can be a benefit or a drawback depending on your goal. |
| Provides glycine? | Yes. Glycine is the carrier amino acid. | No. The carrier is citric acid. | The glycine in a normal serving is small, so do not assume glycine study results carry over. |
| Research on sleep | A 2025 randomised trial used magnesium bisglycinate and reported modest changes in an insomnia score. | We have not found a comparable sleep trial of citrate to cite. | Evidence is early either way. See the sleep section below. |
| Muscle function and tiredness | Magnesium contributes to normal muscle function and to the reduction of tiredness and fatigue. | Same authorised nutrient claims apply to magnesium in this form. | These claims relate to the magnesium itself, so both forms qualify. |
| Time of day people often choose | Evening, as part of a wind-down routine | Earlier in the day, so bowel effects do not interrupt the night | Timing is personal. Adjust based on how your body responds. |
| Typical cost per dose | Usually higher | Usually lower | Compare price per mg of elemental magnesium, not price per bottle. |
| Common uses | Everyday top-up, sensitive digestion, evening routines | Everyday top-up, occasional regularity, budget-conscious buyers | Pick the form that matches your main reason for taking magnesium. |
| Safe supplement limit (UK) | Same for both: the NHS says 400mg or less a day of magnesium from supplements is unlikely to cause harm. | Count all magnesium supplements together, not each form separately. | |
Absorption: is glycinate or citrate better absorbed?
Both are considered well-absorbed forms, and the honest answer is that no large trial has pitted glycinate against citrate head to head in healthy adults. What we do have is a set of studies comparing each form with other magnesium types, and they are worth reading carefully.
What the evidence shows for citrate
In a 60-day randomised, double-blind study, the Walker and colleagues trial compared magnesium oxide, an amino acid chelate and magnesium citrate at 300mg a day in people with low magnesium status. Only citrate raised blood magnesium significantly. That is a point in citrate's favour, although the chelate used was an amino acid chelate rather than specifically glycinate.
What the evidence shows for glycinate
The evidence for glycinate leans on tolerability and on the peptide-uptake idea described earlier. The Schuette trial suggested glycinate was better tolerated than oxide, but it studied a specialised group of patients and did not compare glycinate with citrate.
Why "organic vs inorganic" is not a reliable rule
A study of four commercial magnesium preparations found oxide was poorly absorbed, but that chloride, lactate and aspartate performed similarly, and concluded that some inorganic salts can match organic ones. In other words, the form matters, but the label "chelated" or "organic" is not a guarantee on its own. Dose, dissolving ability and the individual all play a part.
If your main reason for taking magnesium is a calmer evening routine, you may also like our sleep supplements range, where magnesium glycinate sits alongside other options.
Digestive tolerance: which is gentler on the stomach?
This is where the two forms differ most in everyday use. Magnesium glycinate is generally described as gentle on digestion, while magnesium citrate is more likely to cause loose stools, particularly if you take a larger amount in one go.
It comes down to how much magnesium stays in the gut. The NHS notes that taking more than 400mg of magnesium for a short time can cause diarrhoea, and the European Food Safety Authority sets a lower supplemental upper level of 250mg a day, based on studies in which mild diarrhoea appeared in a small percentage of adults at around 360 to 365mg a day (see the EFSA opinion). Individual tolerance varies a lot, and citrate tends to reach that threshold sooner.
Practical ways to reduce the chance of digestive upset with any magnesium form: start with a smaller amount, split the daily amount across meals, and take it with food.
Sleep and relaxation: what does the research say?
Glycinate is often the form people reach for in the evening, so it is fair to ask whether the research backs that up. Here is what the studies show, and what they do not.
- A 2012 randomised trial in 46 older adults gave 500mg of magnesium daily for eight weeks and reported improvements in several self-reported sleep measures (Abbasi et al.). The form was not glycinate versus citrate specific.
- A 2021 systematic review of magnesium and insomnia in older adults rated the certainty of the evidence as low to very low, with the true effect sitting somewhere between a benefit and no effect.
- A 2025 randomised, placebo-controlled trial in 155 adults with self-reported poor sleep gave 250mg of elemental magnesium as bisglycinate for four weeks. It found a modest improvement in insomnia severity, but average scores still sat in the sub-threshold insomnia range, so the authors noted that a supplement alone is unlikely to resolve poor sleep for many people (Nature and Science of Sleep).
There is also separate research on glycine itself. A small study of ten healthy men whose sleep was restricted reported less daytime sleepiness and fatigue after glycine before bed (Bannai et al.). Studies like this use about 3g of glycine. The 2025 magnesium trial supplied roughly 1.5g of glycine alongside the magnesium, so the amount in a typical serving is smaller than in the glycine studies, and we should not assume the same results.
Where does that leave you? Magnesium is one part of a sleep routine that also includes light, caffeine timing, regular hours and wind-down habits. Glycinate is a reasonable choice if you want a gentle form for the evening, but the research is still early, and citrate has not been tested in the same way.
Muscles, tiredness and everyday needs
For the jobs magnesium is authorised to support, the form matters less than the amount you actually absorb. Magnesium contributes to normal muscle function, to the reduction of tiredness and fatigue, to normal psychological function and to the normal functioning of the nervous system. Those statements apply to magnesium as a nutrient, so they hold for glycinate and citrate alike.
The NHS gives the amount most adults need as 300mg a day for men and 270mg a day for women aged 19 to 64, and says you should be able to get what you need from a varied diet that includes spinach, nuts and wholemeal bread. A supplement is a top-up, not a replacement for food. If you are active and want to explore how magnesium fits into your routine, our active lifestyle support range is a good place to start.
Which should you choose? A decision table
Find the row that matches your situation. If more than one applies, prioritise the one that matters most to you.
| If you... | Consider | Why |
|---|---|---|
| Have a sensitive stomach or get loose stools easily | Glycinate | Generally gentler, so less likely to upset digestion. |
| Want a magnesium for your evening routine | Glycinate | Gentle on digestion, so less chance of a disrupted night, and it is the form used in the recent sleep trial. |
| Want a long-term daily top-up | Glycinate (or citrate if well tolerated) | Both raise magnesium intake. Tolerance and budget usually decide. |
| Are looking for help with occasional constipation | Citrate, after asking a pharmacist | Its osmotic effect is the reason it is used this way. Persistent constipation needs a GP. |
| Are shopping on a tight budget | Citrate | Usually costs less per dose. Compare price per mg of elemental magnesium. |
| Want magnesium for normal muscle function or to reduce tiredness | Either form | The authorised claims relate to magnesium itself, so pick the one you tolerate. |
| Have kidney problems, take regular medicines, or are pregnant or breastfeeding | Speak to your GP or pharmacist first | Magnesium is cleared by the kidneys and can affect how some medicines are absorbed. |
Can you take magnesium glycinate and citrate together?
Many people do combine them, for example glycinate in the evening and citrate earlier in the day. It is generally not a problem, but the limit applies to your total. If you take both, add up the elemental magnesium from each and keep the combined supplemental amount within the 400mg a day the NHS gives as unlikely to cause harm, or lower if your stomach is sensitive. Keeping to one form is simpler and makes it easier to see how you respond.
How much to take and when
Check elemental magnesium, not the compound weight
This is the most common label mistake. A capsule might say "magnesium glycinate 1,000mg" but supply only around 120 to 140mg of elemental magnesium, because the glycine makes up much of the weight. A real example: our 600mg magnesium glycinate capsule provides 72mg of elemental magnesium, so a serving of one to two capsules supplies 72 to 144mg. Always find the "elemental magnesium" or "magnesium (as bisglycinate)" figure, and compare products on that number.
How much magnesium glycinate should I take a day?
Follow the serving on your label. Our 600mg magnesium glycinate capsules provide 72mg of elemental magnesium each, and the recommended serving of one to two capsules gives 72 to 144mg, which is 19% to 38% of the NRV. That leaves room within NHS guidance for magnesium from food and from any other supplement you take.
Is 500mg of magnesium too much?
It depends on what the 500mg refers to. If it is 500mg of magnesium glycinate (the compound), it supplies only about 60 to 70mg of elemental magnesium, which is well within guidance. If it is 500mg of elemental magnesium from supplements, it is above the 400mg a day the NHS says is unlikely to cause harm, and double EFSA's 250mg supplemental upper level, so it is more than most adults should take without advice from a GP or pharmacist.
Use this table to convert the figure on a label into elemental magnesium.
| Label says | Glycinate: elemental magnesium (12% to 14%) | Citrate: elemental magnesium (about 11% to 16%) |
|---|---|---|
| 500mg | 60 to 70mg | 55 to 80mg |
| 600mg (one of our capsules) | 72mg in ours | 66 to 96mg |
| 1,000mg | 120 to 140mg | 110 to 160mg |
| 1,200mg (two of our capsules) | 144mg in ours | 132 to 192mg |
| 500mg elemental magnesium | Above the NHS 400mg a day supplement guidance for either form. Speak to a GP or pharmacist first. | |
Amounts to know (UK and EU)
- NHS reference amount: 300mg a day for men and 270mg a day for women aged 19 to 64, from food and drink.
- NHS supplement guidance: 400mg or less a day from supplements is unlikely to cause harm.
- EFSA supplemental upper level: 250mg a day, set to limit the risk of mild diarrhoea.
Follow the serving on your product label, and do not assume more is better. If you are sensitive, staying closer to the lower figure is sensible.
Timing
There is no single correct time. Glycinate is commonly taken in the evening, and citrate is often taken earlier in the day because of its bowel effects. Taking magnesium with food can help if you notice stomach upset. If you also take certain antibiotics, thyroid medicine or bone medicines, ask your pharmacist whether to space them apart from magnesium. Our guide to when to take magnesium glycinate covers morning vs evening, food and medicine timing in detail.
Who should speak to a GP or pharmacist first
Check with a healthcare professional before starting any magnesium supplement if you:
- have kidney disease or reduced kidney function
- take regular prescription medicines, including some antibiotics, thyroid medicines and bone medicines
- are pregnant, trying to conceive or breastfeeding
- have ongoing digestive symptoms, or constipation or diarrhoea that does not settle
- are considering magnesium for a specific health concern rather than general intake
The bottom line: glycinate or citrate?
Both forms are well absorbed, and both count towards the magnesium your body uses for normal muscle function and for reducing tiredness. The real differences are practical. Glycinate is the gentler option and a natural fit for an evening routine or a sensitive stomach. Citrate costs less and has a mild laxative effect, which suits some people and not others.
If you are unsure, start with the gentler option at a modest amount, see how you feel over a couple of weeks, and adjust. Whichever you choose, read the elemental magnesium figure and keep your total supplemental intake within NHS guidance.
Vanessa holds a Level 3 Diploma in Nutrition and co-founded NutritionGo, where she leads editorial content. She researches and writes our guides, covering ingredient composition, traditional use and nutrition information, and fact-checks them against UK advertising rules and the GB Nutrition and Health Claims register. Every factual statement is verified against sources such as the NHS, the GB Nutrition and Health Claims register or peer-reviewed research on PubMed before publication. Vanessa is not a registered dietitian or healthcare professional, so this guide is for general information and is not a substitute for personal medical advice.
References
View all 10 references and sources
- NHS. Vitamins and minerals: others (magnesium). Reference amounts and advice that 400mg or less a day from supplements is unlikely to cause harm.
- NIH Office of Dietary Supplements. Magnesium: Health Professional Fact Sheet.
- EFSA Journal, 2025. Safety of magnesium orotate dihydrate as a novel food. Summarises the 250mg a day tolerable upper intake level for supplemental magnesium.
- Walker AF et al. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res, 2003;16(3):183-91.
- Schuette SA, Lashner BA, Janghorbani M. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. JPEN, 1994;18(5).
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnes Res, 2001;14(4):257-62.
- Abbasi B et al. The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial. J Res Med Sci, 2012;17(12):1161-9.
- Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complement Med Ther, 2021.
- Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Nat Sci Sleep, 2025.
- Bannai M et al. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Front Neurol, 2012;3:61.