Why magnesium is so essential for your health

Magnesium supplements are having a moment. Videos uploaded with #magnesium have been viewed 1.3 billion times on TikTok. Claims about its benefits extend far beyond helping people to stay calm and range from boosting heart health to immunity, fitness and even a better experience of the menopause. So what is magnesium’s real role in our health? How many of these claims are backed by science and is it the miracle mineral social media would have us believe?

What are the main benefits of magnesium?

“The body contains proteins called enzymes, and their function is to change or make substances we need,” explains consultant cardiologist Dr Neil Srinivasan. “Magnesium plays a role in over 300 enzymatic reactions within the body, including those responsible for regulating blood pressure and controlling levels of glucose in the blood.”

In addition to keeping your heart healthy, it also helps your muscles function well, your brain to communicate with your body, your immune system to work properly and energy production to fire on all cylinders.

In fact, it is the fourth most abundant mineral in the human body – but there’s a catch. “Magnesium deficiency can easily slip under the radar because we’re really bad at testing it,” says doctor of functional medicine and co-founder of personalised supplement company Humanpeople, Dr Geoff Mullan. It is, he explains, an intracellular ion, meaning that 99 per cent is stored within our cells, not our blood, making it tricky to get an accurate reading of your levels via a blood test. 

Public Health England reports that up to 25 per cent of us are deficient in magnesium. If you are obese, diabetic, a woman (particularly a post-menopausal one), or even if you simply eat a lot of processed food, a deficiency is more likely. 

Heart health

Magnesium does more than help to regulate blood pressure and blood glucose levels, explains Srinivasan. “It also has an instrumental role in maintaining your cellular membranes, your mitochondria [special components within each cell that keep them fuelled and functioning] and the antioxidative pathways that help scavenge free radicals that would otherwise damage your cells and cause multiple diseases. It’s critical to the cardiovascular system.”

Not having enough magnesium has been implicated in a number of cardiovascular disorders, from hypertension to cardiomyopathy and atherosclerosis. But cardiologists most commonly reach for magnesium supplements to treat and prevent heart rhythm abnormalities. 

“Magnesium has a well-known protective benefit for these,” says Srinivasan. “We commonly use intravenous magnesium in hospitals to settle cardiac rhythm abnormalities.” 

That reassuringly regular “thump, thump, thump” in your chest is, Srinivasan explains, the result of cells within your heart contracting as waves of electricity pass through them. Should those cells become irritated, they can start firing up erratically, causing skips, bumps and racing that most people experience as palpitations. Magnesium is known to stabilise this process. 

Supplements can help your heart in other ways too, he explains. “They’ve been shown to improve risk factors for heart disease, stabilising your levels of triglyceride as well as ‘bad’ cholesterol and ‘good’ cholesterol.” 

People with higher levels of magnesium in their diets also have a lower risk of developing type 2 diabetes. “While this is still being studied, it’s thought to be due to magnesium’s ability to help the body break down sugars, reducing the risk of insulin resistance,” Srinivasan says.

Anxiety and depression

Magnesium blocks the activation of a key receptor in the nervous system called the NMDA receptor. “This is key to its specific calming effect,” says Mullan.

Functional MRIs show that when magnesium crosses the blood-brain barrier, it prevents over-excitation in the amygdala – the brain’s emotional centre – diminishing those ruminating thoughts that are a common symptom of anxiety. A supplement called magnesium bisglycinate is particularly good at this, because its formula binds magnesium to an organic compound called glycine, and the latter has also been shown to have this stabilising effect on the central nervous system. The result, as Mullan describes it, can be a sense of “clear, calm, focus”.

That said, while a 2020 systemic review backed magnesium’s benefits for mild symptoms of anxiety and depression, it did not flag any significant associations between magnesium levels and more severe panic or generalised anxiety disorder. 

Sleep

“Magnesium is involved in various processes that could impact sleep,” says Dr Guy Meadows, co-founder and clinical lead of Sleep School. “It plays a role in regulating neurotransmitters and hormones related to sleep, such as melatonin. Additionally, magnesium has a calming effect on the nervous system, potentially reducing stress and promoting relaxation, which are conducive to better sleep.”

A note of caution, however. The research on magnesium’s impact on sleep is “not entirely conclusive”, he says, noting that individual responses can vary. While some studies do suggest a link between magnesium supplementation and improved sleep, more rigorous, large-scale clinical trials are needed to establish conclusive evidence. 

Might it be that magnesium’s influence on sleep stems from its power to reduce anxiety? “I think that’s a powerful factor in it,” says Mullan, who takes magnesium glycinate every evening. “If I’ve been ‘on it’ all day, I just know I’m going to have a much better quality sleep as a result [of taking it].” 

He has witnessed the effect on others too. “Earlier this year, we worked with a CrossFit athlete, helping to optimise his performance. Because athletes train and work hard, they often have higher cortisol or stress levels and so struggle to get to sleep.” This particular athlete, like many others, also wore a device to monitor key aspects of his health. Over the course of two weeks, it tracked dramatic improvements in his sleep. “The only thing that he had changed was adding magnesium glycinate into his routine,” says Mullan. 

Earlier this year, a systematic review concluded that observational studies did suggest an association between magnesium levels and sleep quality. Randomised control tests, on the other hand, were less conclusive. So the jury is still out. But if your insomnia is rooted in mild anxiety, magnesium is worth a shot. 

Muscles and cramping

On social media, however, magnesium’s benefits are lauded for another reason: its supposed effects on fitness and sporting performance. The science of this is largely down to the fact that magnesium counters the effects of calcium. Inside your muscles, calcium binds to proteins, changing their shape and making them contract. Magnesium reverses this work, relaxing your muscles, so if your levels are low you may get cramps, spasms or restless leg syndrome at night.

“Anecdotally, a lot of people say it reduces their cramping and there have been studies on athletes showing it helps with muscle strength, power and endurance,” says Mullan. That said: “There have been a few contradictory studies on muscles and cramping,” says Mullan. Some indicate benefits, others none at all.  

Menopause

There is evidence that magnesium has a positive effect on some symptoms of the menopause too, says Mullan. Progesterone has a taming influence over cortisol, a stress hormone. As progesterone levels drop during the menopause, cortisol increases. Magnesium, says Mullan, seems to help to counteract that. Some also claim that magnesium can help with hot flushes but, says Mullan, “I’ve not seen compelling evidence on that.”

Immune system

As well as giving us that “fight or flight” feeling, cortisol also suppresses the immune system, so magnesium has an indirect, positive impact simply by suppressing cortisol release, says Mullan. But there’s more. 

Our immune systems are bolstered by an antioxidant called glutathione, and magnesium is vital in managing its production, he explains. It also plays an important role in the growth of immune cells like lymphocytes, and in making the proteins that fight infection in the body, explains Mullan. 

B and T cells help the immune system to identify and fight threats. Their activation relies, in part, on an enzyme called phospholipase C, which in turn needs magnesium in order to function. A 2023 review in the Journal of Health Population and Nutrition concluded that magnesium is “essential for optimal immune function and regulating inflammation” and that, under appropriate medical supervision, “enhancing [magnesium] intake could potentially serve as a cost-effective and economically viable strategy for immune regulation and preventing cancer”.

What are the different types of magnesium supplements?

“Some magnesium supplements have a very low bioavailability,” warns Mullan, meaning your body will struggle to absorb and use the magnesium within them. “In particular, magnesium oxide. It’s a laxative, so great if you are blocked up, but it won’t move the dial on your body’s magnesium levels. It’s not a magnesium replenishment supplement.”

Then there’s magnesium citrate, in which magnesium is bound to citric acid. “It has reasonable bioavailability but it also causes pretty significant bowel movements,” says Mullan. “That can actually be helpful if you are reaching for magnesium during the menopause, when constipation rates rise.”

The three big hitters, however, are magnesium bisglycinate, magnesium malate and magnesium threonate. “Threonate and bisglycinate are the two that cross the blood-brain barrier, so are the best to try if you are aiming for a calming effect,” says Mullan. His broad recommendation is to try magnesium bisglycinate if you want help relaxing and winding down, or threonate if you are in search of focus and boosted cognition. 

“On the other hand, malic acid appears to have a positive effect on energy levels, so magnesium malate is the one to take before training sessions if physical performance is your priority.”

Either way, look for the word “chelated” on the bottle. “Chelated is when you have a mineral ion bound to an organic compound. The chelated supplements tend to be the ones that the body can actually absorb. If you have magnesium plus citric acid, that is a chelation. Magnesium plus glycine, that’s a chelation. Magnesium plus oxide is not,” Mullan says.

How to take magnesium

The NHS recommends that adult men aim to eat 300mg of magnesium a day (you can find this in just over 130g of dark chocolate), and women 270mg (contained in about 100g of almonds). Should you wish to pop a pill instead, supplements are typically taken every day, and you can buy them relatively cheaply over the counter.

Other lifestyle and dietary choices can have an impact on their efficacy, though. “Alcohol will increase your excretion of magnesium,” explains Mullan. “And magnesium works synergistically with vitamins B6 and B9, plus calcium, zinc, copper… they all need to be there in decent levels for the effect to be optimal.”

Low on Vitamin D? Taking a magnesium supplement alongside your daily dose of Vitamin D makes sense because magnesium helps your body to absorb and use this vitamin, and is good for keeping bones, teeth and muscles in tip-top shape. 

Foods with magnesium

Modern farming techniques have changed the mineral content of the soil, dramatically lowering magnesium levels in the foods we eat today, suggests Mullan. According to one study, the magnesium in vegetables dropped by 24 per cent between 1940 and 1991, while the ultra-processing of foods depletes levels still further. 

That said, you can still get the magnesium you need from dietary sources, says Srinivasan. “Seeds like pumpkin and chia are especially rich sources, as are nuts like almonds, cashews and peanuts (even in butter form). Spinach is excellent, and shredded wheat cereal is a surprisingly good source.”

And it’s unlikely you’ll consume an excessive amount of magnesium. “Unless you’ve got a kidney disease, the body’s very good at getting rid of excess magnesium if you were to have too much,” says Mullan. 

“It’s not addictive. You don’t become reliant on it so you really don’t have to worry about giving it a shot,” Mullan says.