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Magnesium - Am I Deficient and How Would I Know?

“What are you talking about magnesium deficiency? I’ve never heard of it, and my doctor definitely hasn’t ever mentioned it to me. Sure, iron deficiency, calcium deficiency, I’ve heard of those, those are common. But not magnesium deficiency, it can’t be that common.”

This will be the natural response for those of you hearing of magnesium deficiency for the first time. For most of you this probably isn’t a discussion that’s ever come up at any doctor’s appointment, but it’s actually quite shocking just how common it is and how dramatically it affects our health.

So first off, let me get to the point. It’s estimated that 45% of Americans are magnesium deficient, and 60% do not achieve the average dietary intake (ADI).(1) Other references have differing numbers, some higher and some lower. Part of the reason for this disparity is due to a lack of a standardized and effective means of measuring magnesium deficiency.

For those of you who have ever had your magnesium levels checked you likely had your serum magnesium levels checked. This is the measure of the amount of magnesium floating around in your bloodstream. We measure many different markers of health by looking in the blood, so this should be accurate enough, right?

Well as it turns out, less than 1% of the total pool of magnesium in our body is floating around freely in the bloodstream. The rest is found in our bones (around 60%), other cells of the body (40%), and a little bit left over is inside our red blood cells (different from the magnesium floating freely in the bloodstream). (2)

Now imagine if you had less than 1% of all of your money hidden under your mattress with the rest tucked away in your bank account, and an auditor comes into your home to make an assessment. But instead of looking in your bank accounts, or the worth of your property, he just looks at the cash under the bed. From this and this alone he makes his assessment. Do you see the problem with this?

By measuring a small percentage of our pool of magnesium we have to make major assumptions about the rest of the body. If the blood levels are ‘normal’, then we assume the rest of the body must also be normal. If the blood levels are low, then we assume the rest of the body is also probably low. But unfortunately, as always, it’s just not that simple.

Our body is very effective at maintaining levels of different components of the blood in a safe range in order to keep us alive. In the case of magnesium, we can offset a drop in serum magnesium by dragging it out from our bones and other cells, and stop our kidneys from losing it in our urine. What this means is that if our magnesium levels are too low, our body will still maintain appropriate levels in the blood at the cost of our other organ systems. That’s homeostasis at work. The issue here is that we can’t know if this is happening when we only do a blood test! Just like the auditor making his assessment off a stack of crinkled bills, you and your doctor can only guess as to the true state of your magnesium balance by looking at this blood test. 

Other ways in which we can measure our magnesium levels run into their own problems. RBC-magnesium, which stands for red blood cell magnesium, is the amount actually within the cells in your blood (as opposed to the amount floating outside of these cells in the blood). This test runs into similar issues because it is still such a small percentage of our total supply, however some argue it may provide more accurate info. However, the number one way to assess your magnesium status involves an intravenous infusion of a known amount of magnesium, followed by a 24 hour collection of your urine. The amount of magnesium in the urine can be used to assess how badly your body is craving this mineral, with a much greater degree of accuracy. The downside here is obvious though: who wants to go through all the effort and collect 24 hours worth of pee?

So with that said, we now see why magnesium deficiency can be so hard to measure and classify. But what other evidence do we have to suggest we may be lacking this critical mineral? 

The signs and symptoms that are associated with magnesium deficiency include muscle weakness, spasms, and cramps, as well as fatigue and irritability.The diseases linked to magnesium deficiency include but are not limited to:

  • Metabolic Syndrome
  • Type 2 Diabetes
  • Osteoporosis
  • Hypertension (high blood pressure)
  • Heart Disease
  • Depression
  • Migraine

Now before we get carried away, this is not saying that the above symptoms and conditions are caused by magnesium deficiency. While symptoms like muscle cramps and weakness can often be alleviated by magnesium replenishment, diseases like diabetes and heart disease aren’t going to be reversed with one magic supplement. But there is evidence that it may help and will be discussed further in future articles here.

With a better understanding of how common it is, how to test for it (or try to test for it), and what magnesium deficiency could mean for you, the big questions remaining are: how did this happen, and how do I fix it?

How did this happen? Without getting into an even longer-winded discussion, much of our nutrient deficiencies today come from changes in the food we eat and the decline in the nutrient quality of the soils from which we harvest. Additionally, many other aspects of modern living contribute to magnesium deficiency. A number of pharmaceuticals are known to cause magnesium depletion. This includes diuretics, proton pump inhibitors, antacids, some antibiotics, angiotensin-converting enzyme inhibitors (ACE-I), corticosteroids, oral birth-control pill (OCP), and hormone-replacement therapies (HRT), just to name a few. Alcohol, coffee, strenuous exercise, and soda have also been shown to cause magnesium depletion. Even calcium supplementation can lower magnesium levels by reducing gut absorption. With so many factors having a role to play it really is no surprise that it has become such a widespread issue.

How do I fix it? There are a number of different approaches that you can make to improve magnesium levels and we recommend finding guidance in doing so, whether that be with your GP, Naturopathic Doctor, Nurse Practitioner, Nutritionist, or whomever you trust with your health. Ideally you should aim to get 350-400 mg of magnesium in your diet daily (at least 350 for women and 400 for men), and there are a number of food-tracking apps that can help you understand how much you’re getting from your diet. 

Adding in a magnesium supplement is the best option for making up the difference if your diet isn’t cutting it. Look for forms of magnesium such as magnesium bisglycinate, magnesium threonate, and magnesium malate as they are better absorbed and less likely to cause diarrhea/GI distress than forms such as magnesium oxide. Other nutrients to consider supplementing with include vitamin D and vitamin B6 as these two critical nutrients act synergistically with magnesium. You can also boost magnesium intake by using a high quality electrolyte that includes some magnesium and switching from refined table salt to sea salt as they contain small amounts of magnesium as well.

There is still much to be learned about this pivotal mineral, and I hope to share more with you here as more information comes to light. But from what we now know up to this point, it’s become painfully apparent that we can no longer afford to ignore its role in reaching and sustaining optimal health.

  1. Workinger JL, Doyle RP, Bortz J. Challenges in the Diagnosis of Magnesium Status. Nutrients. 2018 Sep 1;10(9):1202. doi: 10.3390/nu10091202. PMID: 30200431; PMCID: PMC6163803.
  2. Ismail AAA, Ismail Y, Ismail AA. Chronic magnesium deficiency and human disease; time for reappraisal? QJM. 2018 Nov 1;111(11):759-763. doi: 10.1093/qjmed/hcx186. PMID: 29036357.