Magnesium is a highly important mineral as it is required for hundreds of processes in the body. Many people consume insufficient amounts of magnesium (likely due to the high amount of sodium causing increased electrolyte need - our take) and so the supplement market has recently exploded. I'm actually unsure of whether or not I believe many people have an overt deficiency due to lack of consumption, as many magnesium rich foods would not have been widely available to most humans over the course of history. However, many westerners have high sodium intakes and low potassium intakes which may offset the balance of electrolytes and cause an increased need for magnesium in the diet. Also, the high nutrient inhibitor content of western diets through grain products may increase magnesium needs due to lower absorption. So whether or not you should eat up the fear mongering is up to you, but I've never had luck with magnesium supplements personally.

The RDA (recommended daily allowance) for magnesium is set at 400 mg per day. Consuming large amounts in supplemental form can quickly lead to side effects like diarrhea, and mega dosing can be toxic. Many people consume it as a muscle relaxer, but it may not actually help to prevent cramping (due to overall upset of electrolyte balance).

Functions

  • Mineral component of bone formation.
  • Involved in proper nerve transmissions.
  • Required for muscle contraction and relaxation.
  • Integral in protein synthesis.
  • Cofactor in numerous enzyme interactions.

Primary deficiency symptoms and diseases

Magnesium deficiencies are rare, though many people simply consume an inadequate amount in relation to their intake of other minerals like sodium. Theoretically, lowering sodium intake should decrease magnesium needs and make it easier to obtain through diet. 

  • Nausea
  • Lack of appetite
  • Fatigue
  • Anxiety
  • Depression
  • Heart rhythm abnormalities
  • Seizures
  • Muscle cramps and spasms

Food Sources

Most whole foods contain at least some magnesium, but these foods tend to have higher concentrations than others. Be aware that nutrient inhibitors like phytates can reduce absorption substantially, and many magnesium rich foods are also phytate rich foods. While beans, legumes, nuts and seeds are high sources of magnesium on paper, they also have quite poor absorption of minerals unless properly prepared through soaking and sprouting. Whole grains are also sometimes decent sources of magnesium on paper, but practically have a low absorption rate because of phytate.

Some people argue that our soil is magnesium deficient and that foods would have been higher in magnesium just a few hundred years ago, but I don't think that's the whole story. Nutrient inhibitors and electrolyte imbalance are likely to play a much bigger role since farmers who actually care about their crops producing properly will supplement magnesium into their soil in one form or another.

  • Beans and legumes
  • Nuts and Seeds
  • Chocolate (dark chocolate and cocoa powder)
  • Fish and Seafood
  • Whole Grains - you are likely to absorb very little magnesium from grains
  • Green leafy vegetables - absorption may be limited by oxalic acid in these foods

Supplementation

Magnesium supplements are tricky because of the variety of reactions people have to them. Diarrhea is a very common side effect even at normal supplemental dosages and therefore magnesium should preferably be taken some time after meals to reduce the likelihood of malabsorption. These are the common forms:

  • Magnesium oxide - very common, tends to have high rate of side effects
  • Magnesium citrate - also common, lower side effects, but some companies "fake" their citrate supplements
  • Magnesium malate - my favorite form, as it has a low rate of side effects and the malic acid seems to help with muscle soreness
  • Magnesium aspartate - like calcium, this is typically found in foods and can be easily absorbed
  • Magnesium sulfate (epsom salt) - usually better as a soak, when taken internally it has strong laxative properties

Who needs it most?

  • Those with electrolyte imbalances
  • People with a high phytate or oxalate intake
  • Frequent consumers of alcohol
  • Those with malabsorptive disorders

Other tips

Despite the vast amount of fear mongering surrounding magnesium insufficiency, an easier way to correct inadequate intake than taking supplements is to get proper electrolyte balance by reducing sodium and increasing potassium intake. Also, reducing the amount of nutrient inhibitors in the diet can be a night and day difference in terms of you actually absorbing more magnesium from your diet rather than stacking pills or powder on top of your food.