Food Supplements Purity Criteria (Magnesium L-threonate Monohydrate) England Regulations 2026
Summary
The Secretary of State for Health and Social Care has proposed the Food Supplements Purity Criteria (Magnesium L-threonate monohydrate) (England) Regulations 2026, laying draft regulations before Parliament for approval. The instrument establishes chemical specifications, assay requirements, and heavy metal limits (arsenic not more than 1 ppm, lead not more than 0.5 ppm, cadmium not more than 0.2 ppm, mercury not more than 0.1 ppm) for magnesium L-threonate monohydrate as a permitted source of magnesium in food supplements.
Food supplement manufacturers should note that this draft SI sets maximum limits for arsenic (1 ppm), lead (0.5 ppm), cadmium (0.2 ppm), and mercury (0.1 ppm) that are stricter than some existing general food metal limits. Manufacturers currently using magnesium L-threonate monohydrate should review their supply chain specifications and quality control testing to ensure compliance with the proposed commencement date of 13th August 2026.
What changed
These draft regulations would establish for the first time legally defined purity criteria for magnesium L-threonate monohydrate as a mineral substance permitted for use in food supplements in England. The Schedule sets out comprehensive specifications including chemical identity (CAS 500304-76-7, molecular weight 312.51 Da), assay ranges (magnesium 7.2% to 8.3%, L-threonate 82% to 91%), solubility, pH, and maximum contaminant limits for heavy metals and oxalic acid.
Manufacturers and suppliers of food supplements containing magnesium L-threonate monohydrate should monitor the Parliamentary progress of this instrument and prepare to ensure their products meet the specified assay and purity requirements by the proposed commencement date of 13th August 2026. Quality control and testing protocols may need adjustment to verify compliance with the new heavy metal limits.
Archived snapshot
Apr 22, 2026GovPing captured this document from the original source. If the source has since changed or been removed, this is the text as it existed at that time.
Draft Legislation:
This is a draft item of legislation and has not yet been made as a UK Statutory Instrument.
Draft Regulations laid before Parliament under regulation 6(3) of the Nutrition (Amendment etc.) (EU Exit) Regulations 2019, for approval by resolution of each House of Parliament.
Draft Statutory Instruments
2026 No.
FOOD, ENGLAND
The Food Supplements Purity Criteria (Magnesium L-threonate monohydrate) (England) Regulations 2026
Made
Coming into force
13th August 2026
The Secretary of State makes these Regulations in exercise of the powers conferred by regulation 3 and in accordance with regulation 5(1) of the Nutrition (Amendment etc.) (EU Exit) Regulations 2019 (“ the 2019 Regulations ”)().
There has been open and transparent consultation in accordance with Article 9 of Regulation (EC) No 178/2002 of the European Parliament and of the Council of 28 January 2002 laying down the general principles and requirements of food law, establishing the European Food Safety Authority and laying down procedures in matters of food safety().
In accordance with regulation 6(3) of the 2019 Regulations, a draft of this instrument has been laid before Parliament and approved by a resolution of each House of Parliament.
Citation, commencement, extent and application
- —(1) These Regulations may be cited as the Food Supplements Purity Criteria (Magnesium L-threonate monohydrate) (England) Regulations 2026 and come into force on 13th August 2026.
(2) These Regulations extend to England and Wales.
(3) These Regulations apply to England only.
Purity criteria for magnesium L-threonate monohydrate
- The purity criteria for magnesium L-threonate monohydrate are set out in the Schedule to these Regulations.
Signed by authority of the Secretary of State for Health and Social Care
L.S.
Name
Parliamentary Under-Secretary of State
Department of Health and Social Care
Date
Regulation 2
Schedule PURITY CRITERIA FOR MAGNESIUM L-THREONATE MONOHYDRATE
| Synonym | Magnesium L-threonate |
| Definition | |
| Chemical name | Magnesium (2R,3S)-2,3,4-trihydroxybutanoate monohydrate |
| CAS number | 500304-76-7 () |
| Chemical formula | C 8 H 16 MgO 11 |
| Molecular weight | 312.51 Da |
| Colour (solid) | White |
| Assay | Magnesium: 7.2% to 8.3%
L-threonate: 82% to 91% |
| Description | A water-soluble white powder which is manufactured via a chemical synthetic process. |
| Identification | |
| Solubility | Soluble in water at 1% concentration at 25℃ and that is clear in solution at 1% concentration. |
| pH USP () (1% in H₂O) | 5.8 to 7.0 |
| Purity | |
| Loss on drying | Not more than 5.0% (105℃/4 hours) |
| Oxalic acid/oxalate | Not more than 0.5% (as oxalic acid) |
| Arsenic | Not more than 1 ppm |
| Lead | Not more than 0.5 ppm |
| Cadmium | Not more than 0.2 ppm |
| Mercury | Not more than 0.1 ppm |
Explanatory Note
(This note is not part of the Regulations)
These Regulations set the purity criteria for the mineral substance magnesium L-threonate monohydrate, as a source of magnesium, as set out in the Schedule to these Regulations (regulation 2).
An impact assessment has not been produced for this instrument as no, or no significant, impact on the private, voluntary or public sector is foreseen.
An Explanatory Memorandum has been published alongside this instrument at www.legislation.gov.uk.
(1) S.I. 2019/651, amended by S.I. 2026/412. There are other amending instruments but none are relevant. These powers are exercised by the Secretary of State who is the “appropriate authority” for regulations applying in relation to England, as defined in regulation 5(4)(a).
(2) EUR 2002/178, to which there are other amending instruments but none are relevant.
(3) This is a reference to the CAS Registry Number assigned to this preparation by the Chemical Abstracts Service. This is available at https://www.cas.org/cas-data/cas-registry
(4) United States Pharmacopoeia (USP), published by the United States Pharmacopeial Convention in Rockville, Maryland, USA. General Chapter 791 pH of the USP was revised in 2014 by a Supplement to the USP, published on 1st December 2014 (ISBN number 1936424223). USP is a nonprofit scientific organisation that develops and disseminates public compendial quality standards for medicines and other articles. The USP is available at https://www.usp.org
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