Magnesium is essential for health. But can supplements really help with digestion, muscle pain, anxiety and sleep? | Antiviral

Scarlett Johansson’s recent comments about using magnesium to aid digestion and improve sleep have sparked a surge of public interest, prompting dietitian Danielle Shine to field a flood of inquiries on Instagram. The actress told beauty outlet Byrdie that the mineral “is so helpful,” a claim that quickly spread across social media and prompted many to wonder if they should follow suit. Experts stress that magnesium is an essential nutrient required for blood‑pressure regulation, bone health and numerous metabolic processes, but the body cannot synthesize it and must obtain it from foods such as nuts, seeds, legumes, leafy greens and brown rice. While some small studies suggest modest sleep benefits from supplementation, the evidence is inconsistent, with variations in dosage, magnesium form and measurement of sleep outcomes making it difficult to draw firm conclusions.

The broader scientific picture reveals several limitations and potential downsides to indiscriminate magnesium use. Sports dietitian Dr Evangeline Mantzioris notes that research on sleep quality is fragmented, and that proper sleep hygiene—reducing light exposure, limiting caffeine and managing stress—should be prioritized before turning to supplements. Magnesium’s laxative properties, especially in oxide form, can be useful for constipation but may cause nausea, abdominal cramping and diarrhoea in athletes whose intense training already sensitises the gut. Moreover, the Australian Institute of Sport classifies magnesium as a Group C supplement for athletes, indicating insufficient evidence that it enhances muscle recovery or prevents cramps; any relief from warm magnesium baths is likely due to heat rather than the mineral itself.

Health professionals caution that taking magnesium without a confirmed deficiency carries risks, including low blood pressure, respiratory difficulties, irregular heart rhythms and, in extreme cases, cardiac arrest. The British Dietetic Association recommends magnesium supplementation only when a deficiency is identified, typically after a doctor orders a blood test. Marketing narratives that portray magnesium as a panacea for stress, anxiety or pregnancy‑related issues are not supported by robust data, and experts warn that such claims exploit consumers’ fears of hidden deficiencies. Consequently, while magnesium remains vital for overall health, its routine oral supplementation should be approached judiciously and guided by medical advice rather than celebrity endorsement.

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