Magnesium – Are you deficient?


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By Helena Granziera

When one considers the minerals and nutrients central to the body’s functioning, magnesium rarely springs to mind. And yet, this quiet achiever is responsible for some of your body’s most significant functions: heartbeat regulation, bone remineralization, muscle contractions, and blood pressure regulation. Despite the important role magnesium plays in human functioning, reports (e.g., DeNicolantonio et al., 2018) estimate that between 20 and 30% of adults meet the guidelines for clinically significant levels of hypomagnesemia, or magnesium deficiency. So what exactly is magnesium and what role does it play in exercise?

What is it?

Magnesium is the fourth most common mineral in the human body (Schwalfenberg & Genius, 2017) and is primarily located in the muscles and bones. It can help to improve sleep quality, to reduce stress, and aids healthy digestion. Emerging research also suggests that magnesium may help reduce symptoms of depression (Eby & Eby, 2006). Importantly, it also plays an important role in muscle contraction and may help to prevent injury. Magnesium helps muscles to relax, which contributes to greater flexibility and a potential reduction in muscles cramps and tightness. 

Magnesium and Exercise

Extensive research has established an association between magnesium and exercise performance. Indeed, studies of this relationship revealed boosts in exercise performance for athletes, the elderly, and people with chronic disease (Zhang et al., 2017). In one study (Golf & Gruttner, 1998), triathletes who consumed magnesium recorded faster times in swimming, running, and cycling.

So why is this the case? It appears that magnesium plays a key role in helping your body to move blood sugar into your muscles more quickly. This helps to remove lactic acid that may result in fatigue – which means you can lift that bit more or run that bit faster. Other studies also suggest that magnesium may improve your muscle strength (Matias et al., 2010) and may increase the efficiency of your heart’s ability to pump blood throughout the body. Magnesium also plays a vital role in your recovery, as it helps muscles to relax – therefore avoiding those pesky cramps!

If you are exercising regularly, this mineral is particularly important because when you exercise strenuously, magnesium is lost through sweat and urine. In fact, your body requires between 10 and 20% more magnesium than when you are resting.

How do I know I’m getting enough magnesium?

Without blood tests, magnesium deficiencies can be hard to diagnose. Things to look
out for include:
– Excessive or unusual fatigue
– Muscle spasms
– Muscle weakness
– Muscle stiffness
– Loss of appetite
– Nausea
At FitnessLab, we can order a Serum Magnesium blood test through Laverty Pathology for a more precise assessment.

Recommended intake of Magnesium

Below are the recommended daily intakes (RDIs) and estimated average requirements (EARS) for magnesium among adults. Don’t worry – we’ll explain what this looks like in terms of your diet below.

(Source: Australian Government Health and National Medical Research Council:

Magnesium and your diet

The good news is that magnesium is widely available in a range of tasty and nutritious foods. Good sources of magnesium include leafy green vegetables, legumes, beans, nuts, seeds, soy milk, dairy milk, yoghurt, whole grains and avocado. Some examples include:

  • pumpkin seeds, 30g (156mg)
  • chia seeds, 30 g (111mg)
  • almonds, 30g (80mg of magnesium)
  • spinach, boiled, ½ cup (78mg)
  • cashews, 30g (74mg)
  • peanuts, ¼ cup (63mg)
  • soymilk, 1 cup (61mg)
  • oatmeal, 1 cup cooked (6 mg)
  • bread, whole wheat, 2 slices (46mg)
  • avocado, cubed, 1 cup (44mg)
  • rice, brown, cooked, ½ cup (42mg)
  • milk, 1 cup (24mg)

Consider throwing an extra handful of spinach in your salad, swapping white rice for brown rice, and snacking on nuts or seeds between meals. 

Want to know more about magnesium, supplementation, and your exercise program? Come and talk to us.


DiNicolantonio, J. J., O’Keefe, J. H., & Wilson, W. (2018). Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis. Open heart5(1), e000668.

Eby, G. A., & Eby, K. L. (2006). Rapid recovery from major depression using magnesium treatment. Medical hypotheses67(2), 362–370.

Golf, S. W., Bender, S., & Grüttner, J. (1998). On the significance of magnesium in extreme physical stress. Cardiovascular drugs and therapy12 Suppl 2, 197–202.

Schwalfenberg, G. K., & Genuis, S. J. (2017). The Importance of Magnesium in Clinical Healthcare. Scientifica2017, 4179326.

Zhang, Y., Xun, P., Wang, R., Mao, L., & He, K. (2017). Can Magnesium Enhance Exercise Performance?. Nutrients9(9), 946.

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