Following comments by actress Scarlett Johansson endorsing magnesium supplements to aid digestion and improve sleep, health professionals have weighed in on the efficacy and safety of magnesium supplementation.
Johansson recently told a beauty publication that she takes magnesium for better digestion and sleep quality, a statement that sparked increased public interest, according to dietician Danielle Shine. Shine noted that Johansson’s celebrity status often leads to a surge of inquiries from individuals considering magnesium supplements for similar benefits.
Magnesium is an essential mineral involved in numerous bodily functions including blood pressure regulation and bone health, and must be obtained through diet, with sources such as nuts, seeds, legumes, leafy greens, and whole grains. However, experts emphasize that magnesium deficiency is uncommon in the general Australian population, typically affecting only those with specific medical conditions like diabetes or bowel disease.
Regarding sleep, some studies suggest magnesium supplementation may improve certain sleep parameters, but findings are inconsistent and limited by variations in study design, dosage, and duration. Sports dietitian Dr Evangeline Mantzioris highlighted that measurements of sleep quality differ across research, and there is insufficient evidence to definitively link magnesium supplementation with improved sleep. She emphasized that addressing sleep hygiene—such as minimizing light and screen exposure and avoiding caffeine—remains a primary approach for sleep difficulties.
On digestive health, magnesium supplements, particularly magnesium oxide, have an established laxative effect by attracting water into the intestines, making them a recognized treatment for constipation in adults. However, Mantzioris cautioned that athletes or physically active individuals should use magnesium supplements carefully, as intense exercise can increase gut sensitivity, leading to gastrointestinal discomfort when combined with magnesium’s laxative properties.
Magnesium’s role in muscle function and metabolism has raised questions about its impact on exercise recovery and muscle cramps. Shine noted that despite magnesium’s biological importance, current scientific evidence does not support supplementation as an effective aid for muscle recovery or cramp prevention. The Australian Institute of Sport classifies magnesium as a Group C supplement, indicating insufficient proof of benefit for athletes.
Claims that magnesium supplementation can alleviate anxiety and stress are also not strongly supported by evidence. While magnesium is involved in nerve transmission and regulation, Shine said there is no convincing data showing broad benefits for nervous system function through supplementation. Mantzioris added that supplement marketing often exploits everyday stress, but underlying causes such as workload cannot be remedied by magnesium.
Health professionals advise that individuals concerned about magnesium deficiency consult a doctor, who can perform blood tests and provide tailored guidance. Routine supplementation without medical indication carries risks; excessive magnesium intake can lead to toxicity manifesting as low blood pressure, respiratory difficulties, abnormal heart rhythms, and in severe cases, cardiac arrest. There is also no conclusive evidence supporting routine magnesium supplementation during pregnancy.
Overall, while magnesium is vital for health, experts recommend obtaining it through a balanced diet and caution against widespread supplementation without confirmed deficiency.