Best Magnesium Supplement UK (2026): Glycinate vs Citrate vs Oxide, and the Sleep research

Our picks at a glance

Product grades reflect testing and form. The main claim (better sleep) is graded Early overall.

Do you need a magnesium supplement?

Magnesium is a mineral involved in hundreds of processes, including muscle and nerve function and energy release. The NHS says adults need 300mg a day (men) or 270mg (women) and that most people can get this from a varied diet: green leafy vegetables, nuts, seeds, wholegrains, beans and pulses are good sources.

A supplement makes more sense if your diet is low in these foods, if you take medicines that lower magnesium (some diuretics or long-term acid-reducing drugs), or if a doctor has found you are low. A normal blood test does not always reflect body stores, so discuss symptoms rather than chasing a number.

How we chose

We checked UK product pages in October 2026 and ranked supplements on:

• Elemental magnesium per serving, clearly stated, and within the NHS guide of 400mg a day from supplements.
• Form: glycinate, citrate and malate ranked above oxide.
• Buffering: we flag "buffered" glycinates that mix in oxide.
• Independent testing: Informed Sport scored highest.
• Price per month and extras: single-ingredient products preferred.

Glycinate vs citrate vs oxide: which form is best?

"Absorption" here is a general guide from the chemistry and small studies; there are no large trials showing one form improves health outcomes more than another.

Which magnesium supplement should you buy?

Viridian High Potency Magnesium Bisglycinate: best overall

Two capsules give 200mg elemental magnesium as 100% bisglycinate, with no oxide blended in, according to the product page. That leaves room for magnesium from food and stays well within the NHS guide. You can take one capsule for 100mg. Caveat: no published independent test, and larger pots are better value than the 60.

DRV+ Magnesium Glycinate: best budget glycinate

The page states 300mg elemental magnesium as bisglycinate, not just the 1,500mg compound weight, which makes comparison easy. A pouch lasts 30 days. Caveat: 300mg is a full day's need; combined with another magnesium product it could exceed 400mg. No published third-party test.

BetterYou Magnesium Max 3-in-1 Powder: best powder

Half a teaspoon (2g) gives 375mg elemental magnesium as glycinate, citrate and malate, unflavoured. Easy to halve the dose. Caveat: a full dose is close to the NHS guide, and the citrate part may loosen stools.

Puresport Ultra Magnesium: best tested option

The only magnesium we found showing Informed Sport certification. It combines citrate (110mg), bisglycinate (95mg) and taurate (20mg). Caveat: it also contains beetroot powder and vitamin D3, which you may not want, and it costs more than single-ingredient glycinates.

Bare Biology Ready & Rested: premium two-month pot

Three capsules give 375mg (100% of the label reference amount), and 180 capsules last 60 days. The brand says it tests each batch. Caveat: the ingredients show it is buffered: 85% bisglycinate and 15% magnesium oxide. That is not a problem for most people, but it is not pure glycinate.

Together Health Marine Magnesium: cheapest per day

One capsule gives 198mg magnesium from purified seawater for £7.49 a month. Caveat: seawater magnesium is a mix of oxide, hydroxide, carbonate and other forms, generally less well absorbed than glycinate. "Natural" sourcing does not make it work better.

What does the evidence say about magnesium and sleep?

Magnesium for sleep is one of the most-searched supplement topics, so it is worth being precise. A 2021 meta-analysis pooled three randomised trials in 151 older adults with insomnia. People taking magnesium fell asleep about 17 minutes faster than with placebo; total sleep time rose by about 16 minutes but this was not statistically significant. The authors rated the evidence low to very low quality and said it was not good enough for doctors to make firm recommendations.

A 2024 systematic review found five of eight sleep studies reported improvements, but the studies were small, used different doses and forms, and some included other active ingredients. The authors thought magnesium was most likely to help people with low magnesium status to begin with.

The claim that glycinate is specifically better for sleep comes from the fact that glycine (the amino acid it is bound to) has been studied for sleep on its own. The amount of glycine in a typical magnesium dose is much smaller than in those studies, and no trial has compared magnesium forms for sleep directly.

Who should be careful?

• Kidney disease: do not take magnesium supplements without your doctor's advice, because the kidneys clear excess magnesium.
• Medicines: separate magnesium from tetracycline or quinolone antibiotics, bisphosphonates and levothyroxine by a few hours. Ask your pharmacist.
• Digestive upset: reduce the dose or switch from citrate or oxide to glycinate.
• Stacking products: add up magnesium from multivitamins, electrolyte drinks, sleep blends and powders.

Can you get enough magnesium from food instead?

For most people, yes. A handful of almonds or cashews, a portion of spinach or other dark leafy greens, a bowl of porridge or wholegrain cereal, beans, lentils and a square of dark chocolate all add meaningful amounts. Because food also brings fibre, potassium and other nutrients, a diet built around these foods is a better first step than a capsule. A supplement is a top-up, not a replacement, and it is worth asking your GP to check your levels if you have symptoms such as persistent muscle cramps or twitches, especially if you take diuretics or long-term acid-reducing medicines.

What to avoid

• Labels that only show compound weight (for example "1,000mg magnesium glycinate") without elemental magnesium.
• "Buffered" glycinates sold as pure glycinate at a premium.
• Very high doses for sleep: above 400mg from supplements adds side effects without evidence of extra benefit.
• Magnesium sprays and bath salts sold for absorption through the skin: evidence for meaningful absorption is weak.

Bottom line

If you choose to take magnesium, a glycinate giving 100 to 300mg of elemental magnesium a day is a sensible default, and Viridian's unbuffered bisglycinate is our top pick. Keep total supplement intake at 400mg or less, check for medicine interactions, and treat better sleep as a possible bonus rather than a promise, particularly if your diet already includes plenty of nuts, seeds, greens and wholegrains.