What to look for when buying magnesium?

Check one: elemental magnesium per serving, with %NRV

The front of the bottle shows the compound weight; the nutrition panel should show the magnesium itself, as its own line, with its share of the 375mg nutrient reference value. 300mg and 80% is the figure a lifter wants. If the line is missing, the front number is the compound and the dose is unknown.

Check two: the form, named first in the ingredients

Ingredients run in descending order of weight. Bisglycinate first means a chelated glycinate; citrate first means citrate; oxide first means an oxide product whatever the name on the front. Firoz and Graber measured oxide absorption at around 4%; Walker's 2003 trial found citrate well absorbed; glycinate has good human data and the lowest laxative effect. Buy on the form that leads the list.

Check three: capsules per serving

Elemental per capsule and per serving are different numbers, and brands know which one looks better. Two capsules for 300mg is normal for a glycinate; three or four for less is a cost problem; one capsule claiming 300mg elemental as bisglycinate is physically impossible and tells you the figure is compound weight.

Check four: a third-party test panel, shown

UK supplements are foods and nobody tests them before sale. A brand that pays an independent lab and shows the panel, lead, mercury, arsenic, cadmium, total viable count, yeast and mould, E. coli, salmonella, staph, has proved its contents. Lab tested in a bullet point is a phrase, not a panel.

Check five: a UK manufacturer and address

Under the Food Supplements Regulations 2003 the label must carry the name and address of the business responsible. UK made under GMP means a manufacturer working to a recognised quality system inside UK food law, with an address you can find. No address is a reason to put it back.

Check six: no claims beyond the register

Magnesium may say it contributes to normal muscle function, normal psychological function, a reduction of tiredness and fatigue, electrolyte balance, normal energy-yielding metabolism, normal protein synthesis, the normal functioning of the nervous system and the maintenance of normal bones and teeth. It may not say sleep, anxiety, cramps, testosterone or weight loss. A brand that does is telling you what it thinks of the rules.

Check seven: no proprietary blends

Every ingredient with its amount. A blend that lists forms without a split, or herbs without doses, cannot be compared with anything and cannot be trusted to deliver the elemental figure on the front.

Check eight: price divided by servings

Capsules per bottle divided by capsules per serving gives servings; price divided by servings gives cost per day. Under 25p a day for 300mg elemental as glycinate is the benchmark; a £9.99 bottle that lasts 20 days is dearer than a £19.99 bottle that lasts 90.

What to check on the label

Questions people also ask

What should I look for when buying magnesium supplements?

The elemental figure with %NRV, the form named first, capsules per serving, a shown test panel, a UK address, no unauthorised claims, no blends, and cost per day.

What is the best form of magnesium to buy?

Bisglycinate for daily use; citrate if you also want a bowel effect. Never oxide as a magnesium source.

How much elemental magnesium should a supplement have?

About 300mg per serving, which is 80% NRV and the UK reference intake for men, under the 400mg a day guidance level for supplements.

Does UK made matter when buying magnesium?

It puts an accountable manufacturer under UK food law behind the label, with GMP as the quality floor. It is a floor, not a guarantee; the test panel is the proof.

How much should magnesium cost in the UK?

About 22p a day for 300mg elemental as glycinate, which is what Futuro Labs Magnesium Glycinate costs. Above 40p you are paying for the brand.

Sources

1. Futuro Labs Magnesium Glycinate listing, Amazon UK, label and price checked 31 August 2026. https://www.amazon.co.uk/dp/B0BT7Z5VQW
2. Retained Regulation (EU) No 1169/2011, Annex XIII: nutrient reference value for magnesium 375mg. https://www.legislation.gov.uk/eur/2011/1169/annex/XIII
3. The Food Supplements (England) Regulations 2003 (food supplements are regulated as foods in the UK). https://www.legislation.gov.uk/uksi/2003/1387/contents/made
4. Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnesium Research 2001;14(4):257-262. PubMed record
5. Walker AF, Marakis G, Christie S, Byng M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium Research 2003;16(3):183-191. PubMed record
6. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the substantiation of health claims related to magnesium. EFSA Journal 2010;8(10):1807. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1807
7. Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals. Food Standards Agency, 2003 (magnesium guidance level 400mg a day from supplements). https://cot.food.gov.uk/sites/default/files/vitmin2003.pdf

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