Guide
Magnesium for women: forms, evidence and what the claims really mean
The NHS says women aged 19 to 64 need 270 mg of magnesium a day, mostly achievable from diet, and that supplements of 400 mg or less a day are unlikely to cause harm. EFSA authorises roles in muscle and nervous-system function and in reducing tiredness, but no claim that magnesium treats insomnia or anxiety. Glycinate and citrate are popular for being gentle; check the elemental amount per serving.
How much women need, and from where
The NHS states women aged 19 to 64 need 270 mg of magnesium a day. Most people can reach this from a varied diet: green leafy vegetables, nuts, seeds, wholegrains, beans and pulses are all good sources. A supplement is a top-up for a shortfall, not a substitute for that diet. If you do supplement, the NHS advises that taking 400 mg or less a day is unlikely to cause harm, with loose stools the usual sign of taking too much.
What EFSA actually allows magnesium to claim
Magnesium carries several authorised EFSA health claims, which means these are the only roles a product may legally state:
- contributes to normal muscle function;
- contributes to normal functioning of the nervous system;
- contributes to a reduction of tiredness and fatigue;
- contributes to normal psychological function.
Notice what is not on the list: there is no authorised claim that magnesium treats insomnia, anxiety, cramps or migraine. Marketing that promises to "cure" poor sleep or "beat" anxiety goes beyond what the rules permit. If sleep or mood is a persistent problem, that is a GP conversation, not a supplement decision.
The common forms, compared
| Form | What it is | Tolerance and absorption |
|---|---|---|
| Glycinate (bisglycinate) | Magnesium bound to the amino acid glycine. | Commonly chosen for being gentle on the stomach and well absorbed. |
| Citrate | Magnesium bound to citric acid. | Well absorbed; at higher amounts it can have a laxative effect. |
| Oxide | Magnesium combined with oxygen; high magnesium by weight. | Cheaper but less well absorbed; more likely to cause loose stools. |
The headline weight on a label is the weight of the whole compound, not the magnesium itself. What matters is the elemental magnesium per serving, which a good label states clearly. Our deeper comparison of magnesium glycinate vs citrate sets out the trade-offs.
How to choose, and when to check first
- Read the elemental magnesium per serving, not just the compound weight.
- Keep total supplemental magnesium to 400 mg a day or less unless advised otherwise.
- Avoid blends that hide the magnesium amount inside a proprietary mix.
- If you have kidney problems or take other medication, speak to your GP or pharmacist first.
Compare brands
See our roundup of the best magnesium for women, the full magnesium pillar, and the common question of when to take magnesium.
Sources
- NHS: Others: vitamins and minerals, including magnesium (nhs.uk/conditions/vitamins-and-minerals/others/)
- EFSA authorised health claims register (Regulation (EU) 432/2012, retained in GB law)
Frequently asked questions
How much magnesium do women need?
The NHS states that women aged 19 to 64 need 270 mg of magnesium a day, which most people can get from a varied diet including green leafy vegetables, nuts, seeds and wholegrains. If you take a supplement, the NHS advises that 400 mg or less a day from supplements is unlikely to cause harm.
Which magnesium form is best?
There is no single best form. Glycinate (bisglycinate) and citrate are commonly chosen for being well absorbed and gentle on the stomach, while oxide is cheaper but less well absorbed and more likely to loosen stools. The right choice depends on tolerance and budget. Check the elemental magnesium per serving rather than the weight of the compound.
Can magnesium help with sleep and anxiety?
EFSA authorises claims that magnesium contributes to normal nervous-system and psychological function and to the reduction of tiredness and fatigue, but there is no authorised claim that magnesium treats insomnia or anxiety. A product promising to "cure" poor sleep or anxiety is going beyond what UK rules allow. If sleep or mood is a persistent problem, see your GP.
Is it safe to take magnesium every day?
For most healthy adults, a daily supplement of 400 mg or less is considered unlikely to cause harm by the NHS, with loose stools the most common effect at higher amounts. People with kidney problems, or those on certain medicines, should check with a GP or pharmacist first, because the body clears excess magnesium through the kidneys.
This is information, not medical advice, and is not a substitute for a registered clinician. Always read product labels and speak to your GP or pharmacist before starting a supplement.
Editor, Her Vitals
Oliver leads Her Vitals's editorial coverage of women's life-stage health and supplements. He curates and reviews existing branded products across trying to conceive, pregnancy, postnatal, perimenopause, menopause and the senior years, weighing what the evidence supports against guidance from bodies such as EFSA, the NHS and NICE, and is clear that the content is information rather than medical advice.
Last reviewed: 12 June 2026