Magnesium
Magnesium in capsules, tablets, powders and sprays, from bisglycinate to citrate and malate. We explain which form suits sleep, training or a sensitive stomach, and how to read the elemental magnesium on the label.Read more →
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Magnesium forms, labels and daily amounts explained
What magnesium does
Magnesium is a mineral your body cannot make itself, so it has to come from food or a supplement. Wholegrain bread, nuts, seeds, pulses and green leafy vegetables are the main sources. Magnesium contributes to normal muscle function, to the normal working of the nervous system and to the reduction of tiredness and fatigue. It also contributes to normal energy-yielding metabolism, to normal psychological function and to the maintenance of normal bones and teeth. Those are the claims the European food safety authority (EFSA) has approved, and we keep to them. Magnesium sits alongside the rest of our minerals range.
Elemental magnesium is the number to compare
A pack that says 1500 mg magnesium bisglycinate does not give you 1500 mg of magnesium. That figure is the weight of the whole compound, including the glycine the mineral is bound to. The number that matters is the elemental magnesium, the pure mineral itself, usually printed further down the label. Compare that, not the headline figure. Magnesium oxide holds the most mineral per gram but is absorbed poorly. Bisglycinate holds less per gram, is absorbed better and rarely causes loose stools. It is also why magnesium looks low in electrolyte blends: those doses target fluid balance during exercise, not a full day's intake.
The format decides whether you keep taking it
Capsules and tablets are the simplest option: a fixed dose, easy to travel with. Powders let you split the dose across the day, which helps if one large dose upsets your stomach, and they mix into water or a shake. Gummies suit people who dislike swallowing pills, though the dose per gummy is usually modest. Sprays and bath flakes use magnesium chloride on the skin. People like them around training, but absorption through skin is far less studied than swallowing a capsule, so we treat them as an addition, not a replacement.
How we choose the magnesium we stock
We judge a magnesium on three things: the form, the amount of elemental magnesium per serving, and whether the combination makes sense. We prefer bisglycinate and citrate, because both absorb well and bisglycinate is gentle on the stomach. Oxide we carry inside blends, where it adds bulk mineral cheaply, not as the only form. Vitamin B6 next to magnesium is logical; a long list of extras at token doses is not. We buy directly from the brands, our compliance team checks every product before it goes live, and we test batches ourselves. Read how we select.
Who it suits and what to expect
A supplement makes most sense if you eat few wholegrains, nuts and greens, if you train hard, or if you sweat a lot. UK guidance is clear about the ceiling: keep magnesium from supplements at 400 mg a day or less, because more than that can cause diarrhoea in the short term. Take it daily rather than now and then, and give it two to three weeks before you judge the effect. Many people prefer the evening, which fits a calm wind-down routine and our sleep and rest selection. If you have kidney problems or take prescription medicine, speak to your GP first, because the kidneys clear excess magnesium.
Frequently asked questions
Magnesium is an essential mineral. Your body cannot produce it, so you get it from food such as wholegrain bread, nuts, seeds, pulses and green leafy vegetables. It contributes to normal muscle function, to the normal working of the nervous system, to normal energy-yielding metabolism and to the reduction of tiredness and fatigue. People usually reach for a supplement when their diet is light on those foods, when they train regularly, or when they want support for a calmer evening routine.
UK guidance sets a daily amount for adults and a separate ceiling for supplements. Food and supplements together make up your total, so check both before adding a high-strength product.
| Group | Per day |
|---|---|
| Men 19 to 64 | 300 mg |
| Women 19 to 64 | 270 mg |
| From supplements, upper guidance | 400 mg |
Above 400 mg from supplements, diarrhoea is the common short-term effect.
Source: NHSChoose on tolerance and purpose, not on the biggest number on the front of the pack.
| Form | Absorption | Stomach | Suits |
|---|---|---|---|
| Bisglycinate | Good | Gentle | Evening use, sensitive gut |
| Citrate | Good | Can loosen stools | Daytime, sluggish digestion |
| Malate | Good | Usually fine | Active people |
| Oxide | Poor | Laxative effect | Blends, low budget |
| Chloride spray | Unclear via skin | Not applicable | Use after training |
If one form disagrees with you, switching form often solves it.
There is no single correct time. Consistency matters more than the hour. Many people take magnesium in the evening because it fits a wind-down routine, and bisglycinate is comfortable on an empty stomach. Citrate is often better earlier in the day, since it can loosen the stools and you may not want that at night. Taking it with a meal reduces stomach discomfort. If your dose is high, splitting it over two moments is usually kinder.
Give it two to three weeks of daily use before you judge. Magnesium tops up a mineral store rather than acting like a switch, so the change is gradual and often quiet. Pick one thing to track, for example how your legs feel after training or how easily you settle in the evening. If nothing has shifted after a month at a sensible dose, it is reasonable to conclude your intake was already adequate and to stop.
Yes, in most cases. Vitamin B6 is often included with magnesium in the same product and that combination is common. Magnesium and calcium compete for absorption at high doses, so take large amounts of each at different moments rather than together. Many people pair magnesium with vitamin D3 in autumn and winter. If you take prescription medicine, ask your pharmacist about timing, because magnesium can affect the uptake of some medicines.
Unabsorbed magnesium stays in the bowel and draws water in, which softens the stools. That is why oxide and, to a lesser degree, citrate can have a laxative effect, especially at higher doses on an empty stomach. Three things usually help: switch to bisglycinate, split the dose over the day, and take it with food. If you have deliberately chosen citrate for its effect on digestion, that same mechanism is the point.
They are pleasant and popular, particularly after training or in the evening. Both use magnesium chloride applied to the skin. Being honest about the evidence: how much magnesium passes through intact skin has been studied far less than absorption from a capsule or powder, and the amounts are not comparable. Use a spray or flakes as a comfortable extra you enjoy, and rely on an oral form if your goal is to bring your daily intake up.
