Recently, I’ve had a number of people ask me what my thoughts are on taking magnesium supplements. While pharmaceuticals and supplements aren’t a Physio’s area of expertise, I thought I’d take a look at the research and see if there was any merit to the claims behind magnesium.
What is magnesium?
Magnesium is a dietary mineral, meaning that it cannot be produced by the human body and needs to be obtained from our food. Magnesium is an incredibly versatile mineral, interacting with over 300 enzymes in our bodies and making it an important player in multiple body systems. Natural magnesium can be obtained from leafy green vegetables, nuts, beans and animal sources but no single food is particularly high in magnesium. Even the most magnesium rich foods only contain 15-20% of our daily magnesium requirement.
How much magnesium do you need?
The average adult male has approximately 25g of magnesium in their body at any given time. The recommended daily intake ranges from 310-420mg depending on age and sex. This doesn’t seem like a lot but it is estimated that around 68% of Americans are not meeting their recommended intake. Magnesium deficiencies are often asymptomatic in healthy people but can present as loss of appetite, nausea, fatigue and weakness. A lack of magnesium can also cause an increase in blood pressure and decrease in insulin sensitivity. Anyone can have a magnesium deficiency but obese and diabetic people tend to be at an increased risk.
Importantly, the body does not store excess magnesium very well and will only absorb the amount it requires. Because of this, there are relatively few side-effects associated with magnesium supplementation. The most common signs of magnesium over-consumption are gastrointestinal issues like bloating and diarrhea as the body attempts to remove the excess mineral.
Magnesium has become known as a natural muscle relaxant and this is usually the function people enquire about. Theoretically, this makes sense. Calcium is required to bind to muscle cells to facilitate a contraction. When a muscle needs to relax, those same binding sites are filled by magnesium to prevent calcium from re-attaching. In theory, if one were to have a magnesium deficiency, they might experience an increase in calcium binding and muscle contraction - experienced as spasm or cramping.
Unfortunately, the research does not seem to support the theory. A 2012 systematic review (an amalgamation of all the relevant research) found that taking magnesium supplements were not beneficial for relieving cramps in older adults. The study also evaluated research looking at magnesium’s role in relieving pregnancy-related cramps. One study did find a positive effect but this has since been contradicted by two newer studies.
While the current research tends to suggest muscle cramps are not relieved by magnesium, it’s important to note that no research has specifically looked at exercise-induced cramping so we can’t conclusively say that magnesium does NOT help. However, given the general trend of the research to date, it doesn’t seem likely that magnesium is an effective or reliable muscle relaxant.
This doesn’t mean that magnesium is completely useless. Taking supplemental magnesium has been scientifically proven to have some beneficial effects! Some of these include decreasing blood pressure, mild reduction of asthmatic symptoms, increasing insulin sensitivity, improving sleep quality, and possibly aiding in prevention of depression and ADHD. Keep in mind, these positive outcomes are generally found in people with a magnesium deficiency and are unlikely to be as obvious in an already healthy person.
The next time someone asks whether they should be taking magnesium for their tight and sore muscles, my honest answer will be that there is no evidence it will be helpful. Tight muscles are a natural and common occurrence that can be influenced by many factors. Injury, posture, overuse, and biomechanics can all contribute to muscle tightening and it’s unlikely that taking some extra magnesium will alleviate your troubles.
If you want to stay healthy and avoid other magnesium-related issues, make sure you keep eating those leafy greens! If you suspect you have a magnesium deficiency, speak to your doctor or pharmacist for their professional advice.
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