The 5 Best Magnesium Supplements – and What to Consider, According to Experts

Magnesium is what's known as an essential mineral. Though often cited as a sleep fix and for managing anxiety, the true role that it plays in the body is much broader.

Magnesium is involved in over 300 chemical reactions that occur within our cells. Vital for muscle function, nerve health and energy production, most people can get enough by eating a varied and balanced diet rich in leafy greens, beans and pulses.

However, studies have shown that, despite its bioavailability, the majority of adults may be deficient. It's not something that our bodies create naturally, hence why magnesium supplements can be useful.

Best Magnesium Supplements

According to SENr performance nutritionist Dr Sinead Roberts, magnesium deficiencies are most common in older adults, those that drink alcohol, and athletes, who are more prone to losing magnesium through sweat. 'Symptoms may include fatigue, weakness, headaches, anxiety, sleep disorders, nausea, muscle cramps, tremors, high blood pressure and numbness,' she says.

Knowing for certain that a magnesium deficiency is the cause of these symptoms, however, can be tricky. As magnesium is mostly stored inside bone, muscle and soft tissue cells, blood tests aren't accurate for detecting total body magnesium levels, which makes it difficult to diagnose marginal or non-severe deficiencies.

'Definitive testing can also be expensive,' says Roberts, which is why dietary intake is typically considered instead. She says that adults are estimated to need anything from 250mg to 500mg of magnesium per day – while athletes and those that are highly active may need 10-20% more.

If you do decide to increase your magnesium with a supplement, a food-first approach is considered the best initial step. That's because you get additional benefits from eating foods high in magnesium, like extra vitamins, minerals and fibre.

While it's true that upping your magnesium intake can help to avoid the symptoms mentioned before, there's no guarantee supplementing will work. 'It is important to note research findings are mixed in all cases,' she says. 'This may reflect responders and non responders, or it could be that there are only "benefits" when a deficiency is being corrected versus increasing levels over and above this.'

What to Consider

Type

When you’re scanning for a quality magnesium supplement, it’s key to know that not all magnesium is made equal — different types have distinct roles. Some forms, like glycinate, citrate and malate, are more bioavailable and easier on digestion than oxide or sulfate, meaning your body can actually use the mineral rather than shrug it off as waste.

Glycinate tends to be gentler and better suited to calming the nervous system and supporting sleep and relaxation, while citrate and malate can aid general replenishment and recovery.

A blend of different forms can often be a good way to maximise absorption and efficacy while reducing side-effects from overloading on individual types (ie. too much citrate can cause a laxative effect).

Here, Roberts sets out the key distinctions between each:

• Magnesium glycinate: bioavailable and typically taken for sleep or anxiety.
• Magnesium citrate: typically taken as a laxative.
• Magnesium malate: bioavailable and sometimes taken with the aim of reducing pain.
• Magnesium oxide: poorly absorbed and high risk of causing stomach distress.
• Magnesium L-threonate: bioavailable and typically taken as a laxative or with the aim of having a cognitive benefit.
• Magnesium taurate: bioavailable and typically taken with the aim of impacting blood pressure or blood sugar.

Testing

Roberts says that it's a good idea to choose an independently tested product that has been screened for substances banned in sport. 'You might wonder why non-athletes would look for such testing,' she says, 'but supplements are frequently contaminated and many banned substances are banned because they are harmful to health. Third-party tested products (e.g. Informed Sport) reduce this risk.'

Dosage

Look at research-backed dosages. Most adults should aim for up to ~300–400 mg of magnesium daily – a large chunk of which should come from a whole food diet. However, because studies have shown that the majority of adults may be deficient, many may benefit from increasing their magnesium intake by 150-200 mg per day, which can very effectively come from dietary sources.

Though the risks are low, Roberts says it's worth keeping a note of your intake when actively increasing your magnesium levels. 'Taking excess can cause adverse health impacts, including low blood pressure. Given the number of supplements that magnesium is now added to, as well as being prevalent in the diet, this is a risk. Individuals should always check the supplements they are consuming and total up the magnesium.'

Extra Ingredients

If you're looking to treat a specific issue, it's worth considering choosing a supplement with co-ingredients that complement magnesium’s effects and are tailored to your goals – such as sleep and hormone support or stress resilience. Zinc, chamomile and calming amino acids, such as theanine and tryptophan, can enhance rest and recovery without overloading on a single mineral. A thoughtfully blended supplement that mixes highly absorbable magnesium forms with supporting nutrients ticks the boxes for efficacy and versatility.

Time

When to expect results will differ from person to person. 'From a sleep and anxiety perspective, if magnesium glycinate is effective, it may take 1-2 weeks for the effects to be noticed,' says Roberts. 'Looking more widely at the potential impacts of other magnesium supplements, effects on constipation may be seen in 6-24 hours, and muscle cramps similarly 1-2 weeks.'

How We Selected

When choosing the magnesium supplements to feature in this buyer's guide, we assessed the full range of options on the market before cutting down our final list.

We chose products we have personally tried and tested, as well as those recommended by sports performance nutritionist Dr Sinead Roberts. We rewarded options that represent good value for money and those that are third-party tested for banned substances. We assessed the ingredients listed in each supplement and the dosages in relation to the daily intake, prioritising the most bioavailable forms of magnesium.

We also assessed the quality of the packaging of each product and the smell and taste of the capsules. For powders, we tested how easy they were to prepare and how well they mixed with liquid. Recyclable and eco-friendly packaging received bonus points.

The list below is not exhaustive. These are simply some good value and good quality magnesium supplements that we would genuinely buy ourselves.