Magnesium

Your body needs magnesium for more than 300 chemical reactions, from muscle contraction to nerve signalling, energy production and protein building.^[1] About 60% of the magnesium you carry sits in your bones. It is one of the most widely studied minerals in nutrition.

If you have been told to take magnesium for cramps, sleep or a rough luteal phase, this page goes into how oral forms differ, how much you need and what the research shows.

Forms of magnesium

Magnesium is used in supplements in several chemical forms. They differ meaningfully in how well your body absorbs them. This is measured as bioavailability.

Magnesium oxide is one form used in oral supplements. Small studies suggest that it is less readily absorbed than more soluble forms such as citrate. Absorption also depends on the dose and preparation.^[1]

Magnesium citrate is magnesium bound to citric acid. It is among the forms that are more readily absorbed than oxide.^[1]

Magnesium bisglycinate is magnesium bound to the amino acid glycine. Calm Choco combines this form with magnesium citrate. Tolerance can vary from person to person.

How much you need

EFSA sets an adequate intake of 300 mg of magnesium per day for adult women. The same value applies during pregnancy and breastfeeding.^[6]

Magnesium-rich foods include nuts, seeds, pulses, whole grains and green leafy vegetables. Some medicines, including proton pump inhibitors and certain diuretics, can affect magnesium status. If you take regular medication or have kidney disease, ask a healthcare professional before adding a supplement.^[1]

The science on women's health

Period pain

A 2020 review included 16 trials of different micronutrients for primary period pain. Magnesium appeared in a trial of calcium with and without magnesium. The pooled analyses focused on vitamin D and vitamin E, so this was not a meta-analysis establishing the effect of magnesium alone.^[3]

In a 2022 study, 86 women were assigned magnesium citrate and 86 a combined oral contraceptive. Magnesium was taken at 200 mg daily around menstruation over three cycles. Pain scores fell in both groups, more strongly with the contraceptive. The study was unblinded with no placebo group, so it cannot confirm how much improvement was caused by magnesium.^[4]

PMS

Researchers looked at 31 clinical trials in more than 3,000 women of reproductive age, focused on the emotional side of PMS: mood swings, irritability, low mood. Vitamin B6, calcium and zinc had the strongest evidence. For magnesium on its own, the evidence was not strong enough for a clear conclusion. The review was published in Nutrition Reviews in 2025.^[5]

The review found that only one of the 31 trials had a low risk of bias. This is why magnesium’s established nutritional functions and research into PMS relief should be considered separately.^[5]

EU authorised health claims

Under EU law, magnesium is officially authorised to carry the following health claims:

• Magnesium contributes to a reduction of tiredness and fatigue
• Magnesium contributes to normal energy-yielding metabolism
• Magnesium contributes to normal functioning of the nervous system
• Magnesium contributes to normal muscle function
• Magnesium contributes to normal protein synthesis
• Magnesium contributes to normal psychological function
• Magnesium contributes to the maintenance of normal bones
• Magnesium contributes to the maintenance of normal teeth
• Magnesium contributes to electrolyte balance
• Magnesium has a role in the process of cell division^[2]

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References

[1] National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Magnesium-HealthProfessional

[2] Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. Official Journal of the European Union, 25 May 2012. eur-lex.europa.eu

[3] Saei Ghare Naz M, Kiani Z, Rashidi Fakari F, et al. The effect of micronutrients on pain management of primary dysmenorrhea: a systematic review and meta-analysis. Journal of Caring Sciences 2020;9(1):47-56. doi.org/10.34172/jcs.2020.008

[4] Gök S, Gök B. Investigation of laboratory and clinical features of primary dysmenorrhea: comparison of magnesium and oral contraceptives in treatment. Cureus 2022;14(11):e32028. doi.org/10.7759/cureus.32028

[5] Robinson J, Ferreira A, Iacovou M, Kellow NJ. Effect of nutritional interventions on the psychological symptoms of premenstrual syndrome in women of reproductive age: a systematic review of randomized controlled trials. Nutrition Reviews 2025;83(2):280-306. doi.org/10.1093/nutrit/nuae043

[6] EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific opinion on dietary reference values for magnesium. EFSA Journal 2015;13(7):4186. doi.org/10.2903/j.efsa.2015.4186