Magnesium. This unassuming mineral sounds a bit like a character in an X-Men movie – and in many ways it is a nutritional superhero. “Magnesium is involved in more than 300 chemical reactions in the body, helping enzymes carry out various reactions in the body” says New York-based nutritionist Marissa Meshulam.

Some of magnesium’s important functions include blood sugar regulation, maintaining nerve and muscle function, keeping bones strong, boosting immunity and playing a part in keeping your heartbeat steady.

It may even help you get a good night’s sleep and help lower blood pressure. But are we getting enough? “Magnesium is a major mineral, meaning it is needed in larger amounts than other minerals, so it is important that we get sufficient amounts of magnesium in through our diet to help our body function properly,” says nutritionist Lauren Twigge of Lauren Twigge Nutrition.

There’s more. A 2026 clinical trial showed that magnesium L-threonate improved overall cognition in the areas of working memory and reaction times in healthy adults with poor sleep. And a recent 2025 meta-analysis showed that supplementing with magnesium over the course of 12 weeks lowered both systolic and diastolic blood pressure.

The NHS recommends that adult women should be consuming 270mg a day – and the best way to get that is through your diet. Even if you don’t get enough magnesium from what’s on your plate, it’s unlikely you’ll have a true deficiency (symptoms of that would include muscle weakness, irritability, sleepiness and depression). But certain conditions, such as being treated with diuretics, eating a low-nutrient diet, GI diseases such as Crohn’s or coeliac, alcoholism, severe vomiting or diarrhoea or complications with type 2 diabetes can increase your risk.

“When you are deficient in magnesium, certain body functions tend to slow down or stop working altogether which could lead to a loss of appetite, fatigue, and nausea,” says Twigge.

Thinking of supplementing?

If you decide to supplement, there are several different types of magnesium available that all sound similar but have slightly different functions. “Understanding which magnesium you are taking is key to getting the desired results,” points out Meshulam. Here’s what you need to know.

Types of magnesium

Magnesium oxide

One of the most common magnesium supplements, there is some evidence that 400–600 mg of magnesium oxide daily may help prevent migraines, especially in those who experience aura, or who have migraines related to their period. Do make sure you check with your doctor before taking it. The side effect is similar to the effect from the hydroxide form: diarrhoea. “Magnesium oxide is poorly absorbed which means it’s not a great choice for correcting magnesium deficiency. This form is most useful in GI relief, like heartburn or constipation,” says Meshulam.

Magnesium hydroxide

If you’ve ever had Milk of Magnesia to get your insides moving when you’ve felt constipated, this saline laxative is what you were drinking. It works as a laxative by attracting and retaining water in the intestines and increasing the movement of the intestines that gives you the urge to go to the bathroom, and can also be used to relieve heartburn, acid indigestion, and upset stomach.

Magnesium citrate

The clue is in the name: this form of magnesium is found in citrus fruits and is easily absorbed. Magnesium citrate is widely used for constipation, says Twigge, as it increases the amount of water your intestine absorbs, which makes the stool softer and easier to pass. “Magnesium citrate is a great bioavailable form of magnesium, meaning we absorb it well in our guts,” adds Meshulam.

Magnesium chloride

This form of magnesium contains chlorine, and is a common way to supplement. Taken in pill form, it is also easily absorbed. Some research has also suggested it might be useful for treating symptoms of depression, but more work needs to be done in this area.

Magnesium lactate

Magnesium lactate is easily absorbed and often given in slow-release form. It is also used as a food preservative and flavouring — when food says “fortified,” this is usually the type of magnesium it contains.

Magnesium glycinate

“Magnesium glycinate is well absorbed and generally used for the relaxation effects of magnesium without having any laxative effects,” says Meshulam. There is some research showing that this form of magnesium may be useful for depression, and evidence suggests is may be helpful for insomnia.

Magnesium sulfate

Also known as Epsom salts, magnesium sulfate has long been used as an effective treatment for constipation. In addition to its laxative effects, it is often used in a powder or crystal form for a relaxing bath soak.

Magnesium malate

This form of magnesium contains malic acid, which has a sour taste and occurs naturally in foods such as fruit; it’s well-absorbed and has less of a laxative effect, making it a good option for a supplement.

Magnesium l-threonate

“A well absorbed magnesium that is most notable for boosting the concentration of magnesium within our brains,” says Meshulam, who goes on to say that it is often promoted to help with memory retention and depression – though research is still in the very early stages.