Magnesium: Health benefits and risks

What is magnesium?

Magnesium is a mineral found naturally in many foods, including leafy green vegetables, nuts, seeds, whole grains and pulses. It is also available as a dietary supplement in several different forms, such as magnesium citrate, magnesium oxide, and magnesium glycinate.

Around 60% of the body’s magnesium is stored in bones, with the rest found in muscles, soft tissues and bodily fluids. It plays a key role in energy production, muscle contraction, nerve signalling and maintaining a steady heart rhythm.¹

Magnesium is involved in more than 300 biochemical reactions in the body. Without enough magnesium, several systems can be affected.

Some of its core functions include:

• Supporting muscle and nerve function.

• Helping regulate blood pressure.

• Maintaining normal heart rhythm.

• Supporting bone strength.

• Contributing to energy production.

• Helping regulate blood sugar levels.

Because magnesium is involved in so many processes, low levels - known as hypomagnesaemia - may cause a range of symptoms.

Symptoms of low magnesium

Possible symptoms include:

• Muscle cramps or tremors.

• Fatigue.

• Numbness or tingling.

• Abnormal heart rhythms.

• Loss of appetite.

• Nausea.

People at higher risk of low magnesium include those with digestive disorders, type 2 diabetes, alcohol dependence, or those taking certain medicines such as diuretics.

Research suggests there are several magnesium benefits, particularly when levels are low.²

Helps muscle function

Magnesium helps muscles contract and relax properly. Low magnesium levels have been linked to muscle cramps, twitches and weakness. However, evidence for magnesium supplements preventing night-time leg cramps in otherwise healthy people is mixed.³

Supports bone health

Magnesium works alongside calcium and vitamin D to support bone strength. Adequate intake may help maintain healthy bones, particularly as we age. However, magnesium alone does not prevent osteoporosis.

Supports heart health

Magnesium plays a role in maintaining a regular heartbeat and supporting blood vessel function. Some studies suggest that higher magnesium intake may be linked with lower blood pressure, although supplements should not replace prescribed treatment.⁴

May improve energy levels

Magnesium contributes to normal energy metabolism. Low levels can cause fatigue, weakness and reduced exercise tolerance. If a deficiency is present, correcting it may improve energy levels.

Helps control blood sugar levels

Magnesium is involved in insulin function. Some research suggests that adequate magnesium intake may support healthy blood sugar levels, particularly in people with type 2 diabetes. Magnesium should not be treated as a substitute for diabetes medicine.⁵

May help prevent migraines

Magnesium has been studied as a preventive treatment for migraine. Some evidence suggests it may reduce frequency in certain people, although results vary.⁶

May help relieve anxiety

Because of its role in nerve function and how muscles relax, it has been suggested that magnesium might help with anxiety. Low magnesium levels have been linked to symptoms such as irritability and low mood, so correcting a deficiency could, in theory, support emotional wellbeing.⁷

Some small studies suggest magnesium supplements may help mild anxiety, particularly in people who are deficient. But there isn’t strong enough evidence to recommend magnesium as a standalone treatment for anxiety. If anxiety is ongoing, severe or affecting your daily life, it’s important to speak to a healthcare professional about appropriate support and treatment options.

Most people can get enough magnesium through a varied diet. Good sources include:

• Spinach and other leafy greens.

• Almonds and cashews.

• Pumpkin seeds.

• Wholegrain bread and brown rice.

• Beans and lentils.

Magnesium supplements may be helpful if a deficiency is diagnosed or strongly suspected. They are also sometimes used for specific conditions such as migraine prevention or constipation (certain forms of magnesium have a laxative effect).

Different forms of magnesium are absorbed differently and may cause varying side effects.

For most healthy adults, magnesium from food is safe and unlikely to cause issues.

High doses of magnesium supplements can cause:

• Diarrhoea.

• Stomach cramps.

• Nausea.

Very high levels, usually due to excessive supplementation or kidney problems, can lead to more serious symptoms such as low blood pressure or irregular heartbeat.

People with kidney disease should not take magnesium supplements without medical supervision, as their bodies may struggle to clear the excess magnesium.

As with all supplements, it’s advisable to speak to a healthcare professional before starting magnesium if you have a long-term health condition or take regular medicine.

Magnesium is an essential mineral involved in muscle function, nerve signalling, heart rhythm, bone strength and energy production. Many magnesium benefits are most noticeable when levels are low, and a balanced diet usually provides enough for healthy adults.

Magnesium supplements may be useful in certain situations, such as diagnosed deficiency or specific medical conditions, but they are not a cure-all. High doses can cause side effects, and they may not be suitable for everyone.

If you’re concerned about your magnesium intake or symptoms of deficiency, speak to a healthcare professional for advice rather than self-prescribing high-dose supplements.

Is it safe to take magnesium every day?

For most healthy adults, magnesium from food is safe to consume daily and is unlikely to cause harm.
Magnesium supplements can also be taken daily if recommended by a healthcare professional.

However, high doses may cause diarrhoea, stomach cramps and nausea. Very large amounts can be dangerous, particularly for people with kidney problems.

If you are considering daily supplementation, it’s sensible to discuss this with a pharmacist or doctor, especially if you take regular medicine.

Which type of magnesium is best?

There isn’t one “best” type of magnesium-it depends on why it’s being taken.

• Magnesium citrate is commonly used and may be easier for the body to absorb, but can have a mild laxative effect.

• Magnesium oxide contains a higher amount of elemental magnesium but may be less well absorbed.

• Magnesium glycinate is often marketed as being gentler on the stomach.

For constipation, certain forms of magnesium can be effective because they draw water into the bowel. For other uses, your pharmacist can advise on an appropriate option.

Can magnesium help with sleep?

Magnesium plays a role in muscle relaxation and nerve signalling, which has led to interest in its potential effects on sleep. Some people report improved sleep when taking magnesium, particularly if they were previously deficient.

However, evidence is mixed, and magnesium should not replace established treatments for insomnia. If sleep issues persist, it’s important to explore possible underlying causes.