Walk into any Chemist or health food shop right now and you’ll find an entire shelf dedicated to magnesium. Tablets, capsules, powders, oils, sprays, creams, gummies. The marketing promises better sleep, less anxiety, fewer muscle cramps, improved energy, stronger bones and – depending on which brand you’re reading – what amounts to a complete reversal of the general indignities of getting older.
So let’s cut through it. Does magnesium actually do any of this? And should you be taking it?
The honest answer is: it depends. But the fuller answer is considerably more interesting.
Magnesium is not a supplement trend. It is an essential mineral that your body genuinely cannot function without, and it is involved in more than 300 enzymatic reactions – everything from producing energy at the cellular level to regulating muscle and nerve function, maintaining healthy blood pressure, supporting bone density and helping control blood sugar levels.
It also plays a direct role in the production of serotonin, which goes some way toward explaining why magnesium deficiency is frequently associated with low mood, irritability and disrupted sleep.
The problem is that many of us – particularly as we get older – are not getting enough of it. Magnesium is found in leafy green vegetables, nuts, seeds, legumes, wholegrains and dark chocolate, but modern diets often fall short. Soil depletion over decades of industrial farming has also reduced the magnesium content of many foods that used to be reliable sources. Add to that the fact that certain medications – including proton pump inhibitors for reflux, some blood pressure medications and diuretics – actively deplete magnesium levels, and you start to understand why deficiency is more common than most people realise.
Low magnesium doesn’t usually announce itself dramatically. It tends to creep in quietly, which is part of why it goes unrecognised for so long. Common signs include persistent muscle cramps or twitches – particularly in the legs – difficulty sleeping, fatigue that doesn’t improve with rest, headaches, constipation, low mood and a heightened sensitivity to stress. Heart palpitations can also be a symptom, though these always warrant investigation to rule out other causes.
If several of those sound familiar, it’s worth a conversation with your GP. A blood test can check your levels, though it’s worth knowing that standard serum magnesium tests don’t always capture the full picture – most of the body’s magnesium is stored inside cells, not in the blood.
The research is genuinely encouraging in several areas. There is good evidence that magnesium supplementation helps reduce the frequency and severity of leg cramps, improves sleep quality – particularly in older adults – and may help lower blood pressure modestly in people who are deficient. There is also solid evidence supporting its role in reducing migraine frequency and in supporting bone health alongside calcium and vitamin D.
The claims around anxiety and mood are more nuanced but not without basis – several studies have shown improvement in mild to moderate anxiety symptoms with supplementation, particularly in people who were already deficient.
What magnesium is not is a cure for everything. If your fatigue is caused by thyroid disease, your sleep problems by sleep apnoea, or your low mood by clinical depression, magnesium supplements will not fix any of that. It is a mineral, not a medication, and managing expectations is part of using it sensibly.
This is where it gets more complicated, and where I’d encourage some healthy scepticism about the marketing.
Not all magnesium supplements are equal, and the form matters considerably. Magnesium oxide – the cheapest and most widely available form – is poorly absorbed and mostly ends up having a laxative effect rather than meaningfully raising your body’s magnesium levels. If you’ve tried magnesium before and found it didn’t seem to do much, this may well be why.
Better-absorbed forms include magnesium glycinate, which is gentler on the stomach and well suited to people taking it for sleep or anxiety; magnesium citrate, which has good absorption and is a reasonable all-purpose choice; and magnesium malate, which some people find helpful for energy and muscle function.
As for magnesium oil – which is not actually an oil but a highly concentrated solution of magnesium chloride in water, applied to the skin – the evidence is considerably thinner than the price tag suggests. The theory is that magnesium absorbs transdermally, bypassing the digestive system. Some people swear by it, particularly for localised muscle cramps and tension. The research on how much actually crosses the skin barrier is limited and inconsistent. It is unlikely to do you any harm, but if you’re looking for reliable supplementation, an oral form with good absorption remains the better-evidenced choice.
The recommended dietary intake for adults over 50 is around 320mg per day for women and 420mg for men. Supplements typically come in doses of 200–400mg, and starting at the lower end is sensible. Taking magnesium in the evening is popular – and has some logic behind it given its role in sleep and muscle relaxation – and taking it with food reduces the chance of stomach upset.
If you are on any regular medications, particularly those for heart conditions, kidney disease or diabetes, check with your GP before starting supplementation. Magnesium is generally very safe, but it can interact with certain medications and is processed by the kidneys, which matters if kidney function is reduced.
Magnesium is not a miracle. But it is a genuinely important nutrient that a meaningful proportion of older Australians are not getting enough of, and for which good supplementation – the right form, at a sensible dose – can make a real and noticeable difference to sleep, muscle function, energy and general wellbeing.
That is not nothing. In fact, for some people, it turns out to be quite a lot.
Just buy the glycinate, not the oxide. And perhaps skip the oil.