Magnesium is an essential mineral involved in more than 300 enzyme systems throughout the body. It plays a role in muscle and nerve function, energy production, bone health, blood glucose regulation and many other important processes.
With so many magnesium supplements available, it can be confusing to know which type to choose. You may have seen magnesium glycinate, citrate, oxide, chloride, malate and magnesium L-threonate, with different products often marketed for different purposes.
But does the type of magnesium really matter? And do you actually need a magnesium supplement?
The answer depends on the individual.
How much magnesium do you need each day?
Magnesium requirements vary according to age, sex and life stage.
The Australian and New Zealand Nutrient Reference Values provide Recommended Dietary Intakes (RDIs) for magnesium. An RDI is the average daily intake sufficient to meet the requirements of almost all healthy people in a particular age and sex group.
Recommended Dietary Intake of magnesium
| Age/life stage | Male | Female |
|---|---|---|
| 1–3 years | 80 mg/day | 80 mg/day |
| 4–8 years | 130 mg/day | 130 mg/day |
| 9–13 years | 240 mg/day | 240 mg/day |
| 14–18 years | 410 mg/day | 360 mg/day |
| 19–30 years | 400 mg/day | 310 mg/day |
| 31–50 years | 420 mg/day | 320 mg/day |
| 51–70 years | 420 mg/day | 320 mg/day |
| Over 70 years | 420 mg/day | 320 mg/day |
During pregnancy, the RDI is 350 mg/day for women aged 19–30 and 360 mg/day for women aged 31–50. For breastfeeding women, the RDI is the same as the non-pregnant RDI for the relevant age group.
These figures refer to your total dietary magnesium intake. They are not recommendations for how much magnesium you should take as a supplement.
Food first: where can you get magnesium?
For most people, food should be the first place to look when trying to meet magnesium requirements.
Magnesium is naturally found in a wide range of foods, particularly:
- Nuts and seeds
- Legumes
- Wholegrains
- Leafy green vegetables
- Avocado
- Seafood
- Meat
- Milk and other dairy foods
Healthdirect notes that most people get the magnesium they need from food.
Some examples of magnesium-containing foods include:
| Food | Serving | Approx. magnesium |
| Pumpkin seeds (pepitas) | 30 g | 159 mg |
| Chia seeds | 30 g | 114 mg |
| Almonds | 30 g | 80 mg |
| Cashews | 30 g | 75 mg |
| Cooked brown rice | ½ cup | 72 mg |
| Cooked spinach | ½ cup | 57 mg |
| Peanuts | 30 g | 48 mg |
| Cooked salmon | 100 g | 30 mg |
| Milk | 1 cup | 28 mg |
| Wholegrain bread | 1 slice | 25 mg |
| Cooked chicken breast | 80 g | 24 mg |
| Avocado | 75 g | 20 mg |
| Cooked beef mince | 65 g | 18 mg |
These values are examples from the Australian Food Composition Database and can vary depending on the food and preparation method.
What could a food-first day of eating look like?
Meeting your magnesium requirements doesn’t mean you need to eat huge quantities of one particular “superfood”.
Instead, magnesium can be obtained from a variety of foods throughout the day.
For example:
Breakfast
Porridge made with:
- ½ cup oats
- 1 cup milk
- 1 tablespoon chia seeds
- Banana
The oats, chia seeds and milk all contribute magnesium.
Morning snack
30 g almonds.
Nuts and seeds are particularly concentrated sources of magnesium and can be an easy addition to a snack.
Lunch
Wholegrain toast with avocado and eggs, served with spinach and tomato.
The wholegrain bread, avocado and spinach contribute magnesium, alongside many other nutrients.
Afternoon snack
Fruit with yoghurt.
Although these aren’t as concentrated in magnesium as nuts and seeds, they contribute to an overall varied diet.
Dinner
Salmon with:
- ½ cup cooked brown rice
- ½ cup cooked spinach
- Other vegetables
The brown rice, spinach and salmon all contribute magnesium.
This illustrates an important point: magnesium intake doesn’t have to come from one particular food or a supplement. It can be built across the overall diet.
A varied eating pattern that regularly includes wholegrains, legumes, nuts, seeds and vegetables can make a meaningful contribution towards meeting magnesium requirements.
So, what about magnesium supplements?
Magnesium supplements can have a role when dietary intake is inadequate or there is a specific clinical reason for supplementation.
However, taking magnesium simply because it is considered “good for you” does not necessarily mean you will experience additional health benefits.
Magnesium deficiency is uncommon in otherwise healthy adults, although certain health conditions, medications and situations such as prolonged diarrhoea can increase the risk.
If supplementation is appropriate, the type of magnesium, dose, elemental magnesium content, other ingredients and your individual health circumstances should all be considered.
Let’s look at some of the commonly available forms.
Magnesium glycinate
Magnesium glycinate is magnesium bound to the amino acid glycine.
It is generally considered to be well tolerated and is commonly chosen by people who experience gastrointestinal side effects with other forms of magnesium.
You may see magnesium glycinate promoted for relaxation, sleep or stress.
Magnesium is certainly important for normal nervous-system and muscle function, but taking magnesium glycinate doesn’t automatically mean it will improve sleep or reduce stress if your magnesium intake is already adequate.
Magnesium citrate
Magnesium citrate is a commonly used form of magnesium and is reasonably well absorbed.
One of its important characteristics is that it can have a laxative effect.
This may be useful for someone experiencing constipation but may be undesirable for someone who already experiences loose stools or diarrhoea.
If you take magnesium citrate and experience ongoing diarrhoea, it is worth discussing the dose and type of magnesium with your healthcare professional.
Magnesium oxide
Magnesium oxide contains a relatively high proportion of elemental magnesium but is generally less well absorbed than some other forms.
It can also have a laxative effect.
Therefore, seeing a higher number of milligrams on the front of a magnesium supplement does not automatically mean it is the better product.
The form of magnesium, amount of elemental magnesium and reason for supplementation all need to be considered.
Magnesium chloride
Magnesium chloride is another form used in oral magnesium supplements.
It is also found in some topical magnesium products.
Topical magnesium products are often promoted as a way of increasing magnesium through absorption across the skin. However, evidence for meaningful magnesium absorption through the skin is limited compared with oral supplementation.
If you are taking magnesium to address inadequate magnesium intake, oral supplementation is the more established approach.
Magnesium malate
Magnesium malate combines magnesium with malic acid.
It is sometimes promoted for energy, fatigue and muscle health.
Magnesium itself is involved in normal energy metabolism, but this does not mean that taking magnesium malate will necessarily increase energy levels in someone who already has adequate magnesium intake.
As with many supplements, marketing claims need to be considered separately from the evidence for the nutrient itself.
Magnesium L-threonate
Magnesium L-threonate is a newer form of magnesium that has attracted considerable attention because of its potential effects on the brain.
The brain is protected by the blood–brain barrier, a highly selective barrier that helps regulate which substances can move from the bloodstream into the brain.
Magnesium L-threonate is magnesium bound to L-threonic acid, a metabolite of vitamin C. Preclinical research has investigated whether this particular form can increase magnesium concentrations in the brain more effectively than some other forms of magnesium.
This is one reason magnesium L-threonate is often marketed as a “brain magnesium”.
Researchers have therefore investigated whether it may have effects on:
- Memory
- Learning
- Attention
- Cognitive function
- Sleep
- Brain health
Magnesium itself is important for normal nervous-system function and is involved in processes associated with communication between nerve cells.
However, there is an important distinction between a nutrient having a role in brain function and a particular supplement being proven to improve cognition.
What does the research show?
Research into magnesium L-threonate is still developing.
A 2024 systematic review and meta-analysis examining magnesium and cognitive health found that the limited number of randomised controlled trials available at that time were insufficient to draw firm conclusions about the effects of magnesium supplementation on cognition.
More recently, a 2026 randomised, double-blind, placebo-controlled trial investigated magnesium L-threonate in 100 adults aged 18–45 who reported dissatisfaction with their sleep. Participants taking 2 g of a magnesium L-threonate product daily for six weeks showed some improvements in measures of overall cognition and certain aspects of sleep-related outcomes compared with placebo. However, there were no significant differences for several other sleep measures, and the study was relatively small and short-term.
This is interesting research, but one study does not establish magnesium L-threonate as a treatment for cognitive impairment or as a necessary supplement for brain health.
Does crossing the blood–brain barrier mean it is better?
Not necessarily.
The potential ability of magnesium L-threonate to increase magnesium concentrations in the brain is scientifically interesting. However, this does not mean that everyone needs a form of magnesium specifically designed to increase brain magnesium.
If someone already has an adequate magnesium intake, there is no established recommendation that they should routinely take magnesium L-threonate for cognitive enhancement.
More research is needed to determine who may benefit, at what dose and for what specific purpose.
What about the amount of magnesium?
There is another important consideration when looking at magnesium L-threonate products.
The amount of magnesium L-threonate compound listed on a product is not necessarily the same as the amount of actual magnesium it provides.
This is why you need to look at the elemental magnesium amount on the label.
We will come back to this distinction below.
For now, the key point is that magnesium L-threonate should be viewed as an emerging area of research rather than a proven cognitive-enhancing supplement.
What does “elemental magnesium” mean?
When looking at a magnesium supplement, you may notice that the label lists both the form of magnesium and an amount of elemental magnesium.
This can sound complicated, but the concept is quite simple.
Different forms of magnesium, such as magnesium glycinate, magnesium citrate and magnesium oxide, are compounds that contain magnesium combined with another substance.
For example, magnesium glycinate contains magnesium combined with glycine.
The total weight of the magnesium glycinate compound includes both the magnesium and the glycine.
Elemental magnesium refers to the actual amount of magnesium provided by the compound.
For example, if a supplement states:
Magnesium glycinate 1,000 mg — providing elemental magnesium 100 mg
you are receiving 100 mg of magnesium, not 1,000 mg of magnesium.
This distinction is particularly important if you take more than one magnesium supplement.
When working out how much supplemental magnesium you are taking, add together the elemental magnesium amounts from your products rather than adding the total weight of the magnesium compounds.
This is also the number that is relevant when considering the Australian upper level of intake for supplemental magnesium.
Can you have too much magnesium?
Yes.
However, there is an important distinction between magnesium obtained from food and magnesium obtained from supplements or pharmacological sources.
The Australian and New Zealand Nutrient Reference Values set an upper level of 350 mg per day of magnesium from supplements and pharmacological agents for adults.
This upper limit does not apply to magnesium naturally occurring in food.
This means you do not need to add up all the magnesium naturally occurring in nuts, seeds, wholegrains and vegetables and try to keep your total dietary intake below 350 mg.
In fact, the RDI for adult men is 400–420 mg per day, demonstrating why the 350 mg figure cannot be a limit on total magnesium intake.
The 350 mg upper limit specifically relates to magnesium from supplements and pharmacological agents.
For children, the upper limits for supplemental magnesium are lower:
- 1–3 years: 65 mg/day
- 4–8 years: 110 mg/day
- 9–18 years: 350 mg/day
- Adults: 350 mg/day
There is no established supplemental upper limit for infants aged 0–12 months; the Australian NRVs state that magnesium intake should come from breast milk, formula and food.
The upper limits are based primarily on the risk of gastrointestinal side effects, particularly diarrhoea.
What happens if you take too much magnesium?
Excessive magnesium from supplements can cause:
- Diarrhoea
- Nausea
- Stomach cramps
Very high magnesium levels can be more serious and can affect the body’s normal functions.
This is one reason why taking several magnesium products at the same time isn’t necessarily better.
For example, someone could unknowingly take magnesium from a multivitamin, a separate magnesium supplement and a magnesium-containing laxative or antacid.
Always check the labels of the products you are taking to see whether they contain magnesium.
What about kidney disease?
This is particularly important.
People with kidney disease or reduced kidney function should not start taking magnesium supplements without discussing them with their doctor or pharmacist.
The kidneys play an important role in maintaining magnesium balance and removing excess magnesium from the body. When kidney function is impaired, there can be a greater risk of magnesium accumulating in the body.
This means that a supplement that may be appropriate for one person may not be appropriate for someone with impaired kidney function.
If you have kidney disease, speak with your healthcare professional before taking magnesium supplements, particularly higher-dose products.
Magnesium and medications
Magnesium can also affect the absorption of some medications.
For example, magnesium supplements can affect the absorption of some antibiotics and bisphosphonates used to treat osteoporosis.
Some medications can also affect magnesium levels in the body.
If you take prescription or over-the-counter medications regularly, speak with your doctor or pharmacist before starting a magnesium supplement. They can advise whether your medication and magnesium supplement need to be separated by a particular amount of time.
What about magnesium supplements containing vitamin B6?
Another consideration when choosing a magnesium supplement is checking what else has been added to the product.
Some magnesium supplements contain vitamin B6.
This means you shouldn’t only look at the magnesium content if you are taking multiple supplements. Check the full ingredient list to make sure you aren’t unintentionally consuming excessive amounts of another nutrient as well.
Signs of overdosing vitamin B6 to be aware of are symptoms such as tingling, burning or numbness, which can be associated with peripheral neuropathy.
Do you actually need a magnesium supplement?
Not necessarily.
For many healthy people, a varied and balanced diet can provide the magnesium they need.
A supplement may be appropriate when there is inadequate dietary intake, a demonstrated deficiency or another clinical reason identified by a healthcare professional.
Magnesium deficiency is uncommon in healthy adults, although certain health conditions and circumstances can increase the risk. These include some gastrointestinal conditions, type 2 diabetes, increased urinary magnesium losses and alcohol dependence.
If you are experiencing symptoms such as fatigue, muscle cramps or weakness, it is important not to automatically assume that magnesium deficiency is the cause.
These symptoms can have many possible causes, and a healthcare professional can determine whether further investigation is appropriate.
The bottom line: food first, supplements when needed
Magnesium is an essential nutrient and plays an important role in keeping your body functioning normally.
But more magnesium isn’t necessarily better.
Before reaching for a supplement, consider whether your diet is providing regular sources of magnesium such as nuts, seeds, legumes, wholegrains and leafy green vegetables.
If your dietary intake is inadequate or there is a specific reason why supplementation may be beneficial, a supplement can have a place.
And if you do take one, the type, dose, elemental magnesium content, other ingredients, medications and your individual health circumstances all matter.
Food first doesn’t mean supplements are bad. It means supplements should have a purpose.
If you have kidney disease, take medications, have ongoing diarrhoea or other gastrointestinal symptoms, are pregnant, are considering magnesium for a child, or are taking several magnesium-containing products, seek individual advice before supplementing.
Need help working out whether you actually need a supplement?
Feed Your Future Dietetics, provides individualised, evidence-based nutrition support to help you understand your nutritional requirements and make informed decisions about food and supplements.
Rather than recommending supplements simply because they are popular, Feed Your Future Dietetics can help you look at your overall dietary intake, identify potential nutritional gaps and determine whether dietary changes or supplementation may be appropriate for your individual circumstances.
If you’re unsure whether you are getting enough magnesium from your diet, are considering a magnesium supplement, or aren’t sure which type is right for you, get in touch with Feed Your Future Dietetics for individualised nutrition support.
Telehealth consultations are available Australia-wide.
References
- National Health and Medical Research Council (NHMRC), Australian Government Department of Health and Ageing, and New Zealand Ministry of Health. Nutrient Reference Values for Australia and New Zealand: Magnesium. Eat for Health – Magnesium
- Healthdirect Australia. Foods high in magnesium. Healthdirect – Foods high in magnesium
- Healthdirect Australia. Magnesium deficiency – symptoms, causes, treatment & prevention. Healthdirect – Magnesium deficiency
- Chen F, Wang J, Cheng Y, et al. Magnesium and Cognitive Health in Adults: A Systematic Review and Meta-Analysis. Advances in Nutrition. 2024;15(8):100272. PubMed – Magnesium and Cognitive Health in Adults
- Lopresti AL, Smith SJ. The effects of magnesium L-threonate (Magtein®) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Frontiers in Nutrition. 2026. PubMed – Magnesium L-threonate trial
