Magnesium: is more better?

OLYMPUS DIGITAL CAMERAPhysical performance improved in older women given a magnesium supplement.

Magnesium needs a PR agent.  It’s an extremely important mineral nutrient:

  • it plays a role in 300+ metabolic systems
  • it’s a key component of bone
  • it plays a critical role in energy metabolism and blood glucose control

Yet it’s overshadowed by our obsession with calcium.  Magnesium is not found exclusively in one type of food, so there’s no incentive for any food producers to spend money promoting the importance of magnesium, the way calcium is promoted by the dairy industry.  And that’s a shame.

Magnesium status is typically measured by serum levels.  But this actually isn’t a very accurate measure.  The magnesium level in blood is tightly controlled, as too much or too little would be unhealthy.  So you might have “normal” blood magnesium, but levels in your tissues (where magnesium does it’s work) could be lower than ideal.  While you might not have outright symptoms of severe deficiency, you might not be firing on all cylinders, so to speak.  Symptoms of magnesium deficit range from fatigue, irritability, insomnia and rapid heartbeat to muscle weakness, numbness and tingling nerves.  All symptoms that can be caused by dozens of other problems.  So there’s really no good way to accurately assess a person’s magnesium status.

Meanwhile nutrition intake surveys indicate few people are consuming the recommended amount of magnesium:

  1. Adult men: 420 mg/day
  2. Adult women: 320 mg/day

High magnesium foods are primarily plant foods.  Which may be why few people are eating enough magnesium.  Few people eat the bare minimum of plant-based foods everyday.  The best magnesium sources are:

  • seeds and nuts, like sesame, almonds, brazil nuts, sunflower seeds and butter made with these
  • soy beans, edamame and tofu
  • peanuts and peanut butter
  • legumes/beans, such as pinto beans and black beans
  • whole wheat, oats and rye
  • spinach and chard
  • alternative grain foods like buckwheat and quinoa

A recent study done in Italy looked at the effect of magnesium supplements on older women.  Since magnesium deficiency is associated with poor physical performance, can supplements help?  The women were divided into 2 groups:  one group took 300 mg of magnesium (as magnesium oxide) daily; the other got a placebo.  The women were assessed for strength and physical performance before and after the 12 week study with various tests.  They were also evaluated for dietary magnesium intake.

Results: the women on the 300 mg/day magnesium supplement showed significant improvement in the physical tests.  And even more interesting: the women who had poor magnesium intake from diet had the most significant improvements.  In other words, even though their blood magnesium might have been “normal”, the extra magnesium  provided a benefit.  Were their tissue levels depleted?  That was not measured, so we don’t know.

Keep in mind, the study was designed to look at the effect of magnesium on elderly women, who had decreased physical performance due to aging.   Magnesium supplements might help women in this age group, but might be less useful for younger, healthier people.  Another important point: the supplements used were close to the recommended daily intake, not mega doses.

Is more magnesium better?

To boost your magnesium intake, eat more of those high magnesium foods.  In fact, all of those foods listed above are recommended for lots of other reasons: they high fiber, contain healthy fats, are loaded with other key nutrients, are filling and are part of a plant-based diet.

Magnesium supplements come in a variety of forms.  Always take with food.  Magnesium oxide is the most common form.  Magnesium citrate, lactate and aspartate are other forms; pills made from these may be larger.  Because magnesium is a key component of bones, some calcium supplements also contain magnesium.  For more information on magnesium and supplements, check out this Fact Sheet from the National Institute of Health.

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