Magnesium in the UK: The Forms Explained & How to Choose a Supplement

Jul 21, 2026

11 min read

0 Comments

Magnesium is one of the most popular supplements in the UK — and one of the most confusing to shop for, because it comes in so many "forms". This guide explains the main forms in plain English, tells you which claims are actually allowed, and shows how to choose a quality product.

The good news. Magnesium is a mineral with authorised GB/EU health claims (when a serving provides at least 15% of the Nutrient Reference Value). So unlike a botanical, we can tell you accurately what magnesium contributes to — and our Complex adds three more nutrients that each carry their own claims.

The magnesium forms, explained

"Form" just means what the magnesium is bound to — which affects absorption and tolerability, not whether it's "real" magnesium. The main ones:

Bisglycinate

Chelated to glycine — gentle on the stomach and well tolerated. Used in our Complex.

Malate

Bound to malic acid; a popular everyday form. Also in our Complex.

Citrate

Bound to citric acid; widely used and well absorbed.

L-Threonate

A newer form marketed for its handling in the body; sold as a separate product.

Oxide

High elemental magnesium but low absorption; common in cheaper products.

What's in our Magnesium Complex — and the authorised claims

Each 2-capsule serving delivers four nutrients above the 15% NRV threshold. Here's each, with its %NRV and what it's authorised to say:

Magnesium

300mg · 80% NRV

reduces tiredness & fatigue; normal muscle & nervous-system function

Vitamin D

4µg · 80% NRV

normal immune function; normal bones & muscle

Vitamin K2

75µg · 93% NRV

normal blood clotting; maintenance of normal bones

Vitamin B6

1.2mg · 86% NRV

reduces tiredness & fatigue; normal psychological function

(Taurine and black pepper extract are included as recognisable complementary ingredients; they don't carry authorised claims.)

How people take magnesium

General information only — follow your product's label. Magnesium is commonly taken daily, often in the evening as part of a wind-down routine; ours is a two-capsule serving. Some forms (like oxide) can have a laxative effect at higher amounts — chelated forms such as bisglycinate are usually gentler.

Safety & who should be cautious

Check first if relevant. Very high magnesium intakes can cause digestive upset. If you have kidney problems, take medication, or are pregnant or breastfeeding, speak to your GP or pharmacist before supplementing.

How to choose a quality magnesium supplement

Look at elemental magnesium. The number that matters is the elemental magnesium per serving (and its %NRV) — not the weight of the whole compound.
Choose a well-tolerated form such as bisglycinate or citrate if sensitive.
Sensible companions. Vitamins D, K2 and B6 each add their own authorised claims.
Third-party testing with a Certificate of Analysis available.
GMP manufacture, full labelling, reputable UK seller.

Humming Herbs Magnesium Complex

A 7-in-1 chelated magnesium (bisglycinate + malate) providing 300 mg elemental magnesium, with vitamins D3, K2 and B6. Magnesium contributes to the reduction of tiredness and fatigue and to normal muscle function. Third-party tested; full Supplement Facts on the product page.

References & further reading

Great Britain Nutrition and Health Claims (NHC) Register — authorised claims for magnesium, vitamin D, vitamin K and vitamin B6.
GOV.UK — Nutrition and health claims: guidance to compliance.

Important: This article is for general information only and is not medical advice. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle, and are not intended to diagnose, treat, cure or prevent any disease. If you are pregnant, breastfeeding, taking medication or managing a health condition, speak to your GP or pharmacist before taking any new supplement. Keep out of reach of children.