Magnesium Glycinate vs Bisglycinate: What’s the Difference?

Magnesium glycinate and magnesium bisglycinate are usually two names for the same form of magnesium. The difference is mainly in how the compound is named, rather than one being a better or more effective form.

If you’re choosing between the two, I would not base the decision on the words “glycinate” or “bisglycinate alone”. Instead, look at how much elemental magnesium the product provides, who manufactures it, where it is made, the quality standards behind it, and whether it is suitable for you.

Quick Summary

• Magnesium glycinate and magnesium bisglycinate generally refer to the same magnesium compound.
• The “bis” indicates that magnesium is associated with two glycine molecules.
• Magnesium glycinate/bisglycinate is often well tolerated, although digestive side effects can still occur.
• There is no good evidence that a product labelled “bisglycinate” is automatically better than one labelled “glycinate”.
• Always check the amount of elemental magnesium on the label. The weight of the magnesium compound is not the same as the amount of magnesium you are getting.
• The NHS states that taking 400mg or less of magnesium from supplements per day is unlikely to cause harm. This is a safety guideline, not a recommended daily dose.
• When choosing a supplement, look for a reputable manufacturer that is transparent about where the product is made and can demonstrate appropriate quality standards, including current GMP certification where applicable.
• Cheaper doesn’t always mean better value for money. The Food Standards Agency (FSA) advises consumers to “beware of counterfeit products, particularly on the internet if the product’s price is much cheaper than from other suppliers.
• If you have an underlying medical condition, take regular medication, or are unsure whether magnesium is suitable for you, speak to your pharmacist or doctor before taking it.

What Is Magnesium Glycinate?

Magnesium glycinate is a form of magnesium combined with glycine, an amino acid.

You may also see it called:

• magnesium bisglycinate
• magnesium diglycinate

This can make supplement labels confusing because different manufacturers use slightly different names for the same form.

The term bisglycinate is more specific because it describes magnesium associated with two glycine molecules. “Glycinate” is commonly used as the shorter name.

So, when you see magnesium glycinate and magnesium bisglycinate on two different products, don’t automatically assume they are different forms of magnesium.

Magnesium Glycinate vs Bisglycinate: Is One Better?

For most people, no.

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If two products contain the same form of magnesium and provide a similar amount of elemental magnesium, there is no good evidence that choosing “bisglycinate” over “glycinate” will give you better results.

The more useful questions are:

• How much elemental magnesium does it provide?
• Is the manufacturer reputable?
• Where is the product actually manufactured?
• Can the manufacturer demonstrate appropriate quality controls?
• Is the label clear and transparent?
• Does the product contain anything you need to avoid?
• Is the dose appropriate for you?

This is more useful than choosing a product based simply on which name sounds more scientific.

What Does Elemental Magnesium Mean?

This is one of the most important things to understand when comparing magnesium supplements.

The number printed next to the magnesium compound is not necessarily the amount of magnesium you are actually taking.

For example, a product might state:

Magnesium glycinate – 500mg

But then underneath it may say:

Providing magnesium – 70mg

In this example, the product contains 500mg of the magnesium glycinate compound but provides 70mg of elemental magnesium.

That 70mg is the figure you need when working out how much magnesium you are taking.

This is why I would not choose a magnesium supplement simply because it has the biggest number on the front of the packet.

What should you look for?

Check the supplement or nutrition information for wording such as:

“Magnesium – 100mg”

or

“Providing magnesium – 100mg”

That is the amount of elemental magnesium.

It is also worth checking whether the stated amount is per capsule, tablet or gummy, or whether it applies to the whole daily serving. For example, it may say providing 180mg magnesium per 2 gummies.

Is Magnesium Glycinate Well Absorbed?

Different forms of magnesium can vary in how well they are absorbed.

A systematic review of magnesium supplements found that organic forms of magnesium generally appeared to be better absorbed than inorganic forms, although absorption also depends on the dose, formulation and individual factors.

Magnesium glycinate/bisglycinate is one of the organic forms commonly used in supplements.

However, I would be cautious about claims that one magnesium form is automatically “the most absorbable” or “the best magnesium”.

The evidence does not support such a simple conclusion.

If you are comparing glycinate with bisglycinate, the distinction is even less important because these names generally refer to the same form.

Is Magnesium Glycinate Easier on the Stomach?

One reason people choose magnesium glycinate is that it is often considered a relatively well-tolerated form.

However, “gentler on the stomach” does not mean that it cannot cause side effects.

Magnesium supplements can cause:

• diarrhoea
• loose stools
• nausea
• stomach discomfort

The amount you take matters. The NHS specifically states that taking high doses of magnesium, particularly more than 400mg, can cause diarrhoea.

How Much Magnesium Do You Need?

Your daily magnesium requirement is not the same thing as the amount you should take as a supplement.

The NHS states that adults aged 19 to 64 need approximately:

• 300mg per day for men
• 270mg per day for women

This refers to magnesium from your overall diet, rather than a recommended supplement dose.

Magnesium is naturally found in foods including:

• spinach and other green vegetables
• nuts
• wholemeal bread
• whole grains
• beans and other pulses

For most people, a varied and balanced diet should provide the magnesium they need.

What about magnesium supplements?

The NHS states that 400mg or less of magnesium from supplements per day is unlikely to cause harm. Again, this should not be interpreted as a target dose.

You do not need to take 400mg simply because it is below the NHS safety figure.

The appropriate amount depends on your diet, why you are taking magnesium, the product you are using and your individual circumstances.

How Do You Choose a Good Magnesium Supplement?

This is where I think consumers should pay more attention than they often do.

1. Check the elemental magnesium

Don’t be distracted by a large number such as “1,000mg magnesium glycinate”.

Look for the actual amount of elemental magnesium provided per serving.

That is the number that allows you to compare products properly.

2. Look at who actually makes the product

I would favour manufacturers that are transparent about where their supplements are manufactured.

If a brand simply says “made to the highest standards” but gives you no useful information about where the product is manufactured, it is difficult for a consumer to judge the product properly.

Look for clear information about:

• the manufacturing location
• the manufacturer or responsible business
• relevant quality standards
• batch information
• ingredients and amounts

UK Government guidance advises consumers to buy supplements from reputable businesses and to be particularly careful when buying online or through marketplaces where it may be difficult to establish who is selling the product and where it came from.

Cheaper doesn’t always mean better value for money. The Food Standards Agency (FSA) advises consumers to “beware of counterfeit products, particularly on the internet if the product’s price is much cheaper than from other suppliers. However, don’t assume that the most expensive products is the best.

3. Look for GMP certification

I would also look for a manufacturer that can demonstrate current Good Manufacturing Practice (GMP) certification, particularly when you are comparing products from different manufacturers.

GMP is about having controlled manufacturing processes, appropriate quality checks and systems designed to ensure products are made consistently.

There is an important distinction here: food supplements are not regulated in exactly the same way as medicines, and GMP is not a blanket legal requirement for all food supplements in the UK. Some supplement manufacturers voluntarily follow higher manufacturing standards, however, and evidence of appropriate certification can provide additional reassurance about how the product is made.

I would therefore be more comfortable with a supplement from a manufacturer that is open about its manufacturing site and can provide evidence of its quality certification rather than simply making vague claims about quality.

4. Check the label carefully

A good supplement label should make it clear:

• what form of magnesium is being used
• how much elemental magnesium it provides
• how much you should take
• what other ingredients are included
• who is responsible for placing the product on the market

UK food supplement rules require key information such as ingredients, recommended daily dosage and the amount of the relevant vitamin or mineral to be provided on the label.

Can Magnesium Help With General Wellbeing?

This is a question I get quite often.

Magnesium is an essential mineral and is involved in many normal functions in the body. If someone has an inadequate intake, correcting that nutritional gap makes sense.

But that does not mean that everyone who takes a magnesium supplement will notice a clear improvement in how they feel.

What do I normally recommend?

If someone wants to try magnesium for general wellbeing and there are no contraindications, relevant medicine interactions or red-flag symptoms, I would generally approach it as a time-limited trial rather than something they automatically need to take indefinitely.

In my own clinical practice, where appropriate, I would usually suggest giving it a few months and seeing how you get on.

I would not expect someone to necessarily notice a dramatic difference within a few days.

If magnesium is helping because someone had a low intake or was not getting enough from their diet, any noticeable change may take some time. Equally, some people may not notice any difference at all.

The important point is not to keep increasing the dose simply because you have not noticed an effect.

If there is no meaningful benefit after a reasonable trial, there may be little reason to continue taking it purely for general wellbeing.

This is different from treating a confirmed magnesium deficiency, where supplementation may be clinically indicated and the dose should be guided by the underlying cause. In otherwise healthy people eating a varied and balanced diet, magnesium deficiency is uncommon. However, certain medical conditions, medicines and problems affecting absorption can increase the risk of deficiency.

What If You Have a Medical Condition?

This is where I would be more cautious about self-supplementation.

If you have an underlying medical condition, particularly reduced kidney function, speak to your pharmacist or doctor before taking magnesium.

Your kidneys are involved in removing excess magnesium from the body. When kidney function is significantly reduced, magnesium can accumulate more easily.

You should also check with a healthcare professional if you:

• take regular prescription medicines
• take several supplements containing magnesium
• have kidney disease
• have another significant medical condition
• are pregnant or breastfeeding
• are unsure whether magnesium is suitable for you

The NHS Specialist Pharmacy Service highlights the need to consider a person’s medical conditions, medicines and the quality of the supplement when assessing whether a food supplement is appropriate.

Can Magnesium Interact With Medicines?

Yes.

Magnesium can reduce the absorption of some medicines when they are taken together.

This includes certain:

• antibiotics
• medicines for osteoporosis
• thyroid medicines

The exact separation time depends on the medicine.

For this reason, if you take regular medication, I would recommend checking with your pharmacist rather than relying on a general rule about when to take magnesium.

A pharmacist can check your specific medicines and tell you whether you need to separate them.

Magnesium Glycinate for Sleep: Does It Work?

What Does the Research Say About Magnesium Glycinate and Sleep?

There is some early evidence that magnesium bisglycinate may help with sleep, but the research is still limited.

A 2025 randomised, double-blind, placebo-controlled trial studied 155 adults with poor sleep. Participants took either 250mg of elemental magnesium from magnesium bisglycinate or a placebo each day for four weeks. The magnesium group had a statistically significant improvement in insomnia symptoms compared with placebo, but the difference was small.

The study is encouraging, but it has limitations. 155 participants is a relatively small sample, and the treatment period was only four weeks, so we cannot tell from this study whether the benefit would continue over a longer period. The researchers also recommended larger and longer studies with more objective measures of sleep.

So, I would describe the findings as interesting but preliminary. They suggest magnesium bisglycinate may help some people with poor sleep, but there is not enough evidence to say that it is an established treatment for insomnia.

Pharmacist’s Verdict

If you’re deciding between magnesium glycinate and magnesium bisglycinate, I wouldn’t get too caught up in the terminology.

In most cases, they are simply two names for the same form of magnesium.

The more important question is how much elemental magnesium you are actually getting and whether you can trust the product and manufacturer.

I would look for a manufacturer that is transparent about where the supplement is made, provides clear information about its ingredients and can demonstrate appropriate quality standards, including current GMP certification where applicable.

If you are taking magnesium for general wellbeing and have no reason why you should avoid it, a sensible approach can be to try an appropriate dose for a limited period and see whether you notice a worthwhile benefit. I would not expect an immediate effect, and I would not keep increasing the dose if you do not notice anything.

If you have an underlying condition, take regular medication, or are simply unsure whether magnesium is suitable for you, check with your pharmacist or doctor first.

Frequently Asked Questions

Is magnesium glycinate the same as magnesium bisglycinate?

They are generally two names used for the same form of magnesium. “Bisglycinate” is the more specific name because it indicates two glycine molecules are associated with the magnesium.

Is magnesium bisglycinate better than magnesium glycinate?

There is no good evidence that one is better simply because of the name used on the label. If the products contain the same form and amount of elemental magnesium, other factors such as quality, ingredients and price are more important.

What is elemental magnesium?

Elemental magnesium is the actual amount of magnesium supplied by the compound. For example, 500mg of magnesium glycinate does not necessarily provide 500mg of magnesium. Always check the amount listed as “magnesium” or “providing magnesium” on the label.

Is magnesium glycinate easy on the stomach?

It is often well tolerated, but it can still cause diarrhoea, loose stools or stomach discomfort. Higher amounts are more likely to cause digestive side effects.

Can magnesium glycinate cause diarrhoea?

Yes. High doses of supplemental magnesium can cause diarrhoea. The NHS states that taking more than 400mg can cause diarrhoea, while 400mg or less per day from supplements is unlikely to cause harm.

Can magnesium glycinate help with sleep?

There is some emerging evidence that magnesium bisglycinate may modestly improve sleep symptoms in some people. However, the evidence is still limited and it should not be considered a proven treatment for insomnia.

How long does magnesium glycinate take to work?

There is no fixed time because it depends on why you are taking it and whether you were getting enough magnesium beforehand. If you are trying it for general wellbeing, I would not expect an immediate noticeable effect. Where appropriate, a trial over several weeks to a few months can help you decide whether you personally notice a worthwhile benefit.

Can I take magnesium glycinate with my medicines?

Sometimes, but it depends on the medicine. Magnesium can interfere with the absorption of certain medicines. If you take regular medication, check with a pharmacist before starting it.

Can I take magnesium if I have kidney disease?

You should speak to your doctor or pharmacist first. Reduced kidney function can make it harder for the body to remove excess magnesium, so the risks can be different from those in a healthy adult.

What should I look for when buying magnesium glycinate?

Look beyond the large number on the front of the packet. Check the elemental magnesium amount, ingredients, manufacturer, manufacturing location and quality standards. I would favour a manufacturer that is transparent about where its products are made and can demonstrate current GMP certification where applicable.

References

Food Standards Agency – Food supplements guidance
UK guidance on the safe use and purchase of food supplements, including advice on buying from reputable businesses and being cautious of counterfeit products. Food Standards Agency – Food

NHS – Vitamins and minerals: Magnesium
Information on daily magnesium requirements, dietary sources and the safety of magnesium supplements. NHS – Vitamins and minerals: Magnesium

NHS Specialist Pharmacy Service – Using food supplements
Professional guidance on the use, quality and safety considerations of food supplements. NHS SPS – Using food supplements

NHS Specialist Pharmacy Service – Understanding food supplements
Explains how food supplements differ from medicines and the differences in regulation, safety and quality assurance. NHS SPS – Understanding food supplements

Pardo MR, et al. Bioavailability of magnesium food supplements: A systematic review. Nutrition. 2021;89:111294.
Systematic review examining the absorption and bioavailability of different magnesium formulations. PubMed – Bioavailability of magnesium food supplements: A systematic review

Schuster J, et al. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep. 2025;17:2027–2040.
Randomised, double-blind, placebo-controlled trial investigating 250mg of elemental magnesium from magnesium bisglycinate in adults reporting poor sleep. PubMed – Magnesium Bisglycinate and Sleep Study

Clinically reviewed by Sohaib Ahmed (MPharm)
GPhC-Registered Clinical Pharmacist & Independent Prescriber

This article is for general educational purposes and is not a substitute for individual medical advice. If you have an underlying medical condition, take prescription medication, are pregnant or breastfeeding, or are unsure whether magnesium is suitable for you, speak to your GP or pharmacist.