Three Main Causes of Magnesium Deficiency (Part 2)

Body Odor-In my last post, we learned that 56% of the U.S. population is deficient in magnesium. We also learned about the important role magnesium plays in mitochondrial function and how this relates to exercise performance by ensuring your muscle cells have the highest oxidative capacity (ability to produce ATP or “energy”) possible.

In this post we are going to talk about:

  • The OTHER consequences of magnesium deficiency that are not strictly related to mitochondrial function … and…
  • Why over half of the U.S. population is deficient

Other health consequences of magnesium deficiency

The current RDA (recommended daily allowance) levels of magnesium are ~400 mg/day for a healthy adult. According to a large U.S. national survey, the average magnesium intake is approximately 230 mg/day for women and 320 mg/day for men.1 This is a pretty substantial shortfall for men, and particularly women!

The average intake drops even further below the RDA for elderly Americans. What makes this situation worse, however, is that the RDA value is based on the absolute minimum amount necessary in order to prevent severe diseases associated with magnesium deficiency. Even if you meet that 400 mg/day threshold you are still only running at the bare minimum necessary to avoid severe consequences.

Here’s a list of just a few of the diseases that can be caused by low magnesium levels:

The wide array of diseases and symptoms of magnesium deficiency have to do with the fact that approximately 99% of your body’s magnesium is located in bone, muscles, and soft tissue. The other 1% of magnesium is found in plasma and red blood cells.1 Needless to say, creates a lot of places where things can go wrong.

The three reasons we are all starving for magnesium

Reason #1: Low intake of foods rich in magnesium 

Magnesium is part of chlorophyll, the green pigment found in plants, so green leafy vegetables are particularly high in magnesium. The average American consumes foods that are rich in energy and poor in micronutrients such as processed foods, sugar, sodas, and even meat. This is the most significant cause of magnesium deficiency in the U.S.—not enough green vegetables in our diets. Examples of products and ingredients that contain very little magnesium:

  • Meat (very little)
  • Milk (very little)
  • Soda (virtually none)
  • Sugar (virtually none)
  • White flour (virtually none)

Conversely, here’s a list of the foods that have the most magnesium:

Food Serving Magnesium (mg)
Oat bran 1/2 cup 96.0
Spinach (chopped) 1/2 cup 78.0
Swiss Chard (chopped) 1/2 cup 75.0
Brown rice 1/2 cup 86.0
Almonds 1 ounce (23 almonds) 78.0
Lima beans 1/2 cup 63.0

Just 2.5 cups of spinach per day are enough to satisfy the daily requirement. Among this list, the green chlorophyll-rich vegetables are actually the best choice despite the fact that oat bran, for example, has more magnesium. The reason for that is related to bioavailability and absorption, which we’ll get to in the next section.

Reason #2: Poor intestinal absorption of minerals

The pH of the intestinal interior can affect the ability for magnesium to diffuse across your large and small intestines’ intestinal wall.2 In general, the more alkaline your intestines, the poorer your ability to absorb minerals in general and magnesium in particular will be. Most mineral salts, including magnesium, require very low pH to be solubilized and then absorbed. In general, the more alkaline the intestinal interior, the lower the rate of absorption of most minerals.3

Despite the fact that oat bran and brown rice are both very high in magnesium, they’re actually a poor first choice. The reason for this also has to do with absorption. The magnesium in oat bran and many legumes is misleading in that the bioavailability is reduced as a consequence of these minerals being complexed (bound) to phytates.4 Humans are unable to digest phytate, thus phytate impairs the absorption of minerals (mostly zinc) but also magnesium to a lesser extent. In addition, high-dose supplementation with other minerals can result in competition for mineral digestive enzymes and can also impair mineral absorption. For example, relatively high doses of zinc (142 mg/day) have been shown to inhibit magnesium absorption.3

Reason #3: Excessive excretion of minerals

Your kidneys play a major role in magnesium homeostasis by filtering magnesium and then allowing ~95% of this to be reabsorbed, but allowing the remaining 5% (approximately) to go on to be subsequently excreted in the urine.1 Your kidney is able to conserve magnesium and prevent deficiency by reducing its excretion; on the other hand, magnesium might also be allowed to be excreted in larger amounts in cases of excessive intake by being filtered but not then being re-absorbed in the ordinary proportions.1

There are a few factors that can significantly affect the reabsorption step that comes subsequent to kidney filtration:

    1. Alcohol—this DOUBLES the excretion rate of magnesium in both acute (one time) and chronic (frequent) alcohol consumption cases.1
    2. Diabetes mellitus—both type 1 and type 2 diabetics have an increased rate of magnesium excretion as a consequence of general kidney dysfunction.1

Other ways that excessive excretion can come about that are not related to the kidneys’ homeostatic processes being disrupted include:

      1. Gastrointestinal problems— Crohn’s disease, irritable bowel disease, etc. increase the secretion of magnesium into feces.7
      2. Excessive sweating from exercise or sauna can also result in magnesium loss but to a much lesser extent than any of the aforementioned reasons.

Supplementing magnesium? The variety of magnesium you choose matters

Magnesium supplements that are enteric coated are absorbed 67% less than non-enteric coated supplements.5 In a study that compared four forms of magnesium supplements, data suggested lower bioavailability of magnesium oxide, with significantly higher absorption and bioavailability of magnesium chloride, magnesium lactate, and magnesium citrate.6,7 The optimal dose of a magnesium supplement required for maximal absorption is ~123 mg.5 At doses higher than this, most of the magnesium in not absorbed causing GI distress and osmotic diarrhea.1 For this reason high doses of magnesium supplements are used for their laxative effect.


In summary, magnesium deficiency in over half of the U.S. population is largely a consequence of increased consumption of processed foods, meats, and dairy products and fewer green vegetables. In order to combat this major problem we need to change our dietary habits and increase our intake of green vegetables. It should be noted that cooking, especially boiling, green vegetables results in a significant loss of magnesium ions from the vegetables and into the water.8 For that reason, eating a good portion of raw spinach salad is recommended. Supplementing with the right form of magnesium, such as magnesium citrate, is another way that you can raise your magnesium levels. The other factors that regulate the magnesium levels in your body include intestinal absorption and excretion. In times of magnesium deficiency, your intestines try to increase absorption, your kidneys slow excretion, and sometimes magnesium will be pulled out of your bones (this is a risk factor for osteoporosis). Finally, if you spent a weekend binge drinking you definitely need to replenish your magnesium levels with a nice spinach salad (or smoothie) the next day.

WellnessFX tests magnesium in a variety of package: Performance, to Premium, and in our Women’s Health package. Get an overview of all packages here and choose which one is right for you.

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  • Jahnen-Dechent, W., Ketteler, M. Magnesium Basics. Clinical Kidney Journal 5, 3-14 (210).
  • Schweigel, M. & Martens, H. Magnesium transport in the gastrointestinal tract. Front Biosci 5, D666-677 (2000).
  • Spencer, H., Fuller, H., Norris, C. & Williams, D. Effect of magnesium on the intestinal absorption of calcium in man. J Am Coll Nutr 13, 485-492 (1994).
  • Adam, A. et al. Impact of whole wheat flour and its milling fractions on the cecal fermentations and the plasma and liver lipids in rats. J Agric Food Chem 50, 6557-6562 (2002).
  • Fine, K. D., Santa Ana, C. A., Porter, J. L. & Fordtran, J. S. Intestinal absorption of magnesium from food and supplements. The Journal of clinical investigation 88, 396-402, doi:10.1172/JCI115317 (1991).
  • Firoz, M. & Graber, M. Bioavailability of US commercial magnesium preparations. Magnesium research : official organ of the International Society for the Development of Research on Magnesium 14, 257-262 (2001).
  • Walker, A. F., Marakis, G., Christie, S. & Byng, M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium research : official organ of the International Society for the Development of Research on Magnesium 16, 183-191 (2003).
  • Swaminathan, R. Magnesium metabolism and its disorders. Clin Biochem Rev 24, 47-66 (2003).

The posts on this blog are for information only, and are not intended to substitute for a doctor-patient or other healthcare professional-patient relationship nor do they constitute medical or healthcare advice of any kind. Any information in these posts should not be acted upon without consideration of primary source material and professional input from one's own healthcare professionals.