Do you really need magnesium supplements?

Magnesium has been getting a lot of press lately for everything from sleep support and muscle recovery to mental health.

But most people shouldn't need a supplement to get enough, and the evidence for some claims is somewhat limited, so it's worth knowing what's what before you splash out on supplements.

Here we explain why it's important, the signs of a magnesium deficiency to be aware of, and what to know about magnesium supplements if you are planning to take them. 

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Why do you need magnesium and how much do you need?

Magnesium plays a key role in maintaining processes that regulate our bodies, including the release of energy from food, normal muscle and nerve function, and the maintenance of strong bones. 

NHS guidance on magnesium states the following requirements for adults:

• Men (19-64 years old) need 300mg per day 
• Women (19-64) need 170mg per day

Magnesium deficiency symptoms

Magnesium deficiency isn't that common but low levels have been associated with a number of chronic diseases, including heart disease, high blood pressure, stroke and type 2 diabetes, as well as migraine headaches and Alzheimer's.

Some of the symptoms of magnesium deficiency include: nausea or vomiting, loss of appetite, fatigue or weakness, muscle weakness, twitches and cramps and in later stages abnormal heart rhythms or coronary spasms.

Those most at risk of deficiency include people with restricted or unbalanced diets or malabsorption condition such as coeliac disease, Crohn's or ulcerative colitis. 

Older people may also experience lower magnesium levels (hypomagnesaemia) because of an increased difficulty absorbing it from the diet, coupled with reduced appetite.

Some underlying health conditions can lead to low magnesium levels, including poorly-controlled type 2 diabetes, kidney and parathyroid gland disorders, acute pancreatitis and chronic alcoholism.

There are also some medicines that can reduce levels, such as proton pump inhibitors (PPIs), diuretics, and some heart medicine.

Symptoms are often mild to begin with and easy to overlook or mistaken for something else. If you're experiencing symptoms, you should discuss these with your GP to rule out other potential causes. 

Which foods are high in magnesium?

Food that are high natural sources of magnesium include:

• Green, leafy vegetables
• Wholegrain bread, brown rice and some breakfast cereals
• Pumpkin, sesame and sunflower seeds
• Nuts including almonds, cashews, peanuts and Brazil nuts
• Quinoa and soya beans
• Avocado
• Banana

Sprinkling mixed seeds, such as pumpkin and sunflower seeds, on salads or meals, is an easy way to boost your intake, along with upping your leafy green veg or snacking on nuts.

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Magnesium supplements: what are they good for and do they work?

Magnesium as a supplement has approved health claims for:

• contributing to reduction of tiredness and fatigue
• maintaining energy levels
• electrolyte balance and protein synthesis
• normal functioning of the nervous system, muscle and bone function, psychological function and teeth. 

This means there is sufficient evidence of a benefit to support these claims.

However, the evidence for its role as a sleep aid is less concrete, despite what some social media recommendations may lead you to believe. Sleep expert Professor Guy Leschziner told us that there is currently limited evidence to suggest it can help. 

The relative cheapness of basic magnesium supplements means it could be worth a try if you're struggling with sleep. However, before turning to supplements, check out the proven ways to improve your sleep that our expert recommends in our full guide to sleeping better.

When it comes to anxiety, while some studies have shown some improvement in self-reported anxiety, better evidence is needed to show conclusive impacts.

In all cases, a food-first approach is best and, if you do decide to take supplements, be aware that some can interact with other supplements or medication. If you are taking anything, or have an existing health condition and are unsure about its suitability for you, talk to a pharmacist, GP or registered dietitian first. 

It's also worth doing this if you have new symptoms you aren't sure about, before turning to the supplement aisle.

Check out the proven ways to improve your sleep that our expert recommends in our full guide to sleeping better

Types of magnesium supplement

Magnesium supplements are widely available in many different formulations, which can be a bit confusing. Essentially, magnesium needs to be combined with other sources in order to be absorbed by our bodies, and these all have slightly different characteristics.

The main combination forms include:

• Magnesium oxide – commonly used for oral supplements.
• Magnesium glycinate – magnesium and glycine, an amino acid which helps support the central nervous system. 
• Magnesium citrate – magnesium and citric acid. Some studies claim it is more easily absorbed than other types.
• Magnesium malate - combined with malic acid. 
• Magnesium sulphate – also known as Epsom salts. Most often designed for absorption through the skin, eg via a bath, but oral versions are available.
• Magnesium chloride – used in baths, gels and lotions, but can also be taken orally. Small-scale studies suggest it is also more easily absorbed.

Can you take too much magnesium?

Taking too much magnesium (over 400mg) may lead to adverse side effects, including diarrhoea. 

The NHS says there isn't enough evidence to say what the effects might be of taking high magnesium doses for a long time, and advises against it.

If you are taking a magnesium supplement, stick to 400mg or less a day, although you should be able to get all the magnesium you need from a varied and balanced diet.

The supplements you do and don't need - we look at the evidence behind popular supplements, including vitamin B12 and iron, to give you the lowdown

How to buy magnesium supplements

If you do need to take supplements, most pharmacies, health stores and supermarkets have a range of options to choose from. 

Magnesium tablets and gummies usually contain magnesium citrate or oxide. Gummies may be easier if you don't like swallowing pills, but they're typically pricier and may contain added sugar.

Soluble magnesium supplements – effervescent tablets that you dissolve in water – usually contain magnesium citrate or glycinate. They may also contain additional sugars, salt or flavourings. They're typically around £5-£15 per pack.

Magnesium sprays, gels and lotions can be applied directly to the skin. These usually contain magnesium chloride, and will cost anywhere from £10-£20 per bottle. Magnesium flakes and bath soaks can be bought in smaller bags or large tubs, and will typically set you back between £10 and £30.

Always buy from a trusted retailer. Some of the most popular options are listed below:

• Boots - has everything from own-brand tablets to branded multivitamins containing magnesium from Centrum and Osteocare. You can also expect to find soluble magnesium, lotions and oral sprays.
• Holland & Barrett - stocks magnesium oils, multivitamins, capsules, gels and effervescent tablets.
• Superdrug - has an online range of around 20 magnesium-related products, including Centrum, Wellwoman and Pregnacare. It sells gummies, capsules, oils and multivitamins.

You'll also find a selection at supermarkets, including own-brand versions that tend to be competitively priced.

Check the dose

Most magnesium supplements we found are one-a-day versions sold in bottles of 30, but there were also some that require you to take two-a-day for the equivalent daily 100% NRV (Nutrient Reference Value) dose of 375mg of magnesium so read the label before you buy.

This is important for dosage but also for the cost because you can't assume that a bottle of 60 will last you for two months - for example, the daily dose for Boots Magnesium 60 tablets is two tablets, as is Vitabiotics Ultra Magnesium.

What's the cheapest magnesium supplement?

The cheapest magnesium supplement we found when we checked major retailers was at Poundland (£1 for 30, 3.3p per daily dose). Supermarkets and high street pharmacies have cheap own-brand versions too.

For example, Asda (£1.88 for 30, 6.3p per tablet/daily dose), Sainsbury's (£4.40 for 60, 7p per tablet/daily dose) and Tesco (£3.65 for 50, 7p per daily dose) aren't far behind at 7p per tablet (same as Boots' own-brand option). 

This may be even cheaper if you take advantage of multi-buy offers such as three for two deals.

* Prices correct at time of checking on 29 April 2025.

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