Influencers online are raving about the alleged effects of magnesium. They claim it makes you burst with energy and helps with various ailments, such as fatigue and brain fog. But are these claims well-founded, or are they mainly fueled by sellers of dietary supplements? We asked magnesium expert Jeroen de Baaij from Radboud University Medical Center.
How does magnesium function in the body?
‘Magnesium is important for muscles, bones, brain, blood vessels, and the heart. Muscles use calcium to contract and magnesium for relaxation. People with a magnesium deficiency may experience muscle cramps, as relaxation doesn’t work properly.
In the Netherlands, one to two percent of the population has a magnesium deficiency, measured in the blood. The recommended daily amount of magnesium is 350 mg for men and 300 mg for women. This can be obtained through a varied diet rich in green vegetables.
A magnesium deficiency is more common in people taking certain medications, such as strong antacids. This doesn’t apply to mild remedies like Rennies.’
When should you supplement magnesium?
‘Supplementing magnesium only makes sense if a deficiency is proven in the blood. We often see people consulting a doctor with muscle cramps, making it difficult for them to sleep, for example. Influencers sometimes claim that you can identify a magnesium deficiency with a questionnaire, but that’s not true. You need to consult a doctor to have it measured.
If the blood magnesium level is normal, taking extra magnesium is not very effective. The excess magnesium is excreted. Studies on the effects of extra magnesium on sleep, muscle complaints, and fatigue in people with normal blood values showed little to no increase in blood magnesium levels. In people with sleep problems, a cautiously positive effect of magnesium on symptoms was demonstrated. However, this was not objectively measured, in small groups and only through questionnaires. Better studies with a placebo as a control and better measurements are needed to truly demonstrate any potential effect.
Some people claim that you can still have a magnesium deficiency even if your blood values are normal. This is based on the fact that most magnesium is not in the blood but in the bones and soft tissues, such as muscles and the liver. However, there is no evidence that the concentration in these tissues can be low while the blood value is normal. And that doesn’t make sense either.’
Kidney Physiology 