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Q & A: Why is Magnesium Such a Common Deficiency?

A gradual depletion of nutrients from our soils has left many plants (vegetables, nuts, whole grains and seeds) with lower levels of magnesium. Large-scale and non-sustainable agricultural practices only use nitrogen based fertilizers to maximize crop yield rather than quality and neglect to restore trace minerals back into the soil.1.

Our drinking water is also devoid of magnesium because the filtration and water-treatment removes the naturally occurring magnesium. Both tap and bottled water have little or no magnesium and higher levels of fluoride (which binds magnesium) and calcium, both of which can worsen magnesium deficiency. Despite eating a healthy and well-balanced diet a person can develop low magnesium levels over time. The recommended daily allowance (RDA) for magnesium in adults is 4.5 mg/kg/day (about 300 mg/day). A dietary surveys suggest that many North Americans do not get the minimum recommended amounts of magnesium daily.3 Even though the classic symptoms of severe magnesium deficiency are rare, health issues can occur well before overt deficiency.

Another factor that contributes to magnesium deficiency is that it is depleted by a number of common digestive disorders. Since magnesium is absorbed in the small intestine conditions that affect this area of the gastrointestinal system, such as Crohn’s disease, intestinal surgery, and gluten sensitivity (celiac enteropathy) and other conditions can impair absorption.2

Many commonly used medications, such as proton pump inhibitors, diuretics and some antibiotics cause magnesium depletion.3,4 Proton pump inhibitors (i.e. Omeprazole/Losec®, Esomeprazole/Nexium®, Lansoprazole/Prevacid®), block stomach acid which is required for the absorption of magnesium (HCL breaks the chemical bond between magnesium and the anion). 5 Some of these drugs are taken for a long time or repeatedly, which can create a substantial deficiency. This is especially concerning when many elderly are on multiple medications for many years. Older adults are at an increased risk for magnesium deficiency since intestinal absorption of most nutrients can decrease with age.


  • The Magnesium Miracle, by Carolyn Dean, M.D., N.D., Ballantine Books, 2007.
  • Magnesium metabolism and its disorders. Clin Biochem Rev. 2003 May; 24(2):47-66.
  • Ford ES and Mokdad AH. Dietary magnesium intake in a national sample of U.S. adults. J Nutr. 2003;133:2879-82.
  • Rude RK and Olerich M. Magnesium deficiency: Possible role in osteoporosis associated with gluten-sensitive enteropathy. Osteoporos Int 1996;6:453-61.

Q: Can You Test Your Magnesium to Check if You Are Deficient?

A: Magnesium (Mg) deficiency is very common but many people still want to know if this can be tested or confirmed in any way. The published literature says that “there is no simple, rapid and accurate laboratory test to indicate the total body magnesium status.”1 The commonly used blood tests (i.e. serum magnesium) are not sensitive enough to pick magnesium levels inside various cell types (red blood cell, muscle etc.). It is important to point out that a person can still have “suboptimal” total magnesium levels without any lab finding that is out of range. Most experienced clinicians don’t bother using conventional testing methods to assess magnesium deficiency but rather use clinical signs and symptoms (i.e. muscle twitches, palpitations, chronic pain, high blood pressure etc.) to determine deficiency and a need for extra magnesium.


  • Magnesium metabolism and its disorders. Clin Biochem Rev. 2003 May; 24(2):47-66.
  • Konrad M, Schlingmann KP, Gudermann T. Insights into the molecular nature of magnesium homeostasis. Am J Physiol Renal Physiol 2004; 286: F599–F605

Q: Which Foods Have High Levels of Magnesium?

A: In addition to supplementation, these foods should be consumed regularly to increase magnesium levels. The following is a list of the top 5 foods highest in magnesium based on an average serving size. Note: values have been taken from the 2010 Canadian Nutrient File complied by Health Canada.

Amt of Mg (in mg)
Serving size
175 mL (¾ cup)

1) Pumpkin or squash seeds, no shell

175 mL (¾ cup)

2) Brazil nuts, without shell

175 mL (¾ cup)

3) Peas, black-eyed peas, cooked

30 mL (2 Tbsp)

4) Sunflower seeds/butter

150 g (3/4 cup)

5) Tempeh/fermented soy, cooked


Q: Why Are Magnesium and Calcium Frequently Found Together in Products? Do Magnesium and Calcium Work Together?

A: Magnesium and calcium make each other more soluble (easy to dissolve) so that’s why they have always been supplemented together (usually in a 2:1, Cal:Mag ratio) but this doesn’t mean that they need to be given together.1 To quote Dr Carolyn Dean MD “The 2:1 ratio—that was a mistake; a mistaken translation from French researcher Jean Durlach, who said never ever go beyond two parts calcium to one part magnesium in your food, water, or supplement intake combined.”2 This comment does not stipulate that calcium and magnesium should always be taken together but supplement manufacturers and clinicians just assumed it to be the case.

Generally, North Americans eat a high diet high in calcium (mostly due to dairy) diet and have a chronic magnesium deficiency so many people should take extra magnesium (not calcium) in the short term. Emerging evidence suggests that excess calcium intake may cause artery calcification and increases the risk of cardiovascular events after long term supplementation.3 The good news is that magnesium actually can dissolve calcium build up found in arteries (think high blood pressure, atherosclerosis AKA calcification of arteries). In cases of osteoporosis and bone formation (pregnancy) a highly absorbable calcium supplement can be used but it should always be combined with magnesium, other trace minerals and vitamin D3 + K2. The argument could be made that whenever a person is supplementing calcium they should take extra magnesium (1:2, Cal:Mag ratio) since there most likely is an underlying magnesium deficiency and Mg is as important for bone formation as calcium. For general health, a good long term strategy is supplementing with a complete mineral (and vitamin) complex since the body needs all minerals for proper function.


Q: What is The Optimal Dose of Magnesium?

A: This actually varies depending on the person and the form being used. As a general rule most educated clinicians aim for 400mg of elemental Mg per day usually in 2 divided doses. Some specific forms of Mg require higher doses to maximize their therapeutic benefit. For example, Mg orotate has been studied at 3000-6000mg of orate, which may only equal to 200-400 mg of elemental magnesium. To achieve this dose, it can take up to 8 capsules a day of a high quality, fully reacted magnesium supplement.  Some people have a very sensitive digestive system and will get loose stool after a 200mg (2 caps) of a well absorbed form. So the most correct answer about what the right dose is to start low and slowly increase until either beneficial effects are found (i.e. sleep improved, less restless legs, muscles feel relaxed etc.) or until loose stools occur (and then reduce the dose from there). This strategy ONLY is effective if a well absorbed form of Mg is used (i.e. not oxide).

Note: if you have a pre-existing medical condition (especially kidney disease) consult a qualified healthcare practitioner before starting magnesium therapy.

Q: Why do Some Forms of Magnesium (i.e. Mg glycinate) Make me Feel Worse?

A: A number of people have reported that they get a very unusual effect (i.e. cramping, anxiety, excess fatigue etc.) which is opposite to the usual calming effect of magnesium glycinate. Many clinicians have noted paradoxical reactions to even “well absorbed” forms of magnesium.

There always will be variation in the metabolism of any natural substance or pharmaceutical drug depending on the person. Each person has a unique cellular environment and metabolic system which may alter what kind of effect a simple amino acid, herb, vitamin or mineral has. In the case of magnesium glycinate, the glycine (amino acid component) is often responsible for the undesirable effect since it can push liver detox pathways and neurological receptor systems in some more sensitive people. One possible explanation is that magnesium (and glycine) turns on numerous enzymatic pathways in the body and it works together with other co-factors to achieve this. These co-factors include B-vitamins, taurine and other minerals. In clinical practice I have found that if a person experiences an opposite to magnesium then co-administering a high quality b-complex or multivitamin (not a one-a-day) can really improve the effectiveness and tolerability of any form of magnesium.

Q: What’s the Difference Between Magnesium Glycinate and Bisglycinate?

A: Glycinate and bisglycinate are actually the same thing. See the chemical formula and the 2 after the brackets which shows there are two molecules of glycine (hence it’s called bis) – (C2H4NO2)2 Mg. They both are 2 molecules of glycine attached to magnesium. People often refer to it as magnesium glycinate a short formed but the most correct biochemical name is bisglycinate.

Q: What Does “Fully Reacted” Magnesium Mean?

A: Every magnesium (Mg) supplement is a compound of Mg (the cation) and a salt or amino acid (the anion). Just having elemental Mg in a supplement is not possible since it is unstable and therefore must in a compound.  “Fully reacted” refers to the chemical process of creating a particular magnesium compound. For example, magnesium oxide (MgO) is added to citric acid to create magnesium citrate. The goal is to “fully react” both substances to create a greater then 99% Mg and the salt or amino that is on the label. In theory, a fully reacted Mg compound is 100% pure and contains only the magnesium stated on the label but the reality is that the chemical reaction still leaves a small amount of residual MgO but it should be less then 1%. The unfortunate reality is that many magnesium products still contain a larger % of MgO because it has NOT been fully reacted despite what the labels states. Look for a fully reacted Mg from a reputable supplement maker to ensure you are getting the highest quality and purest Mg.

Q: Can Magnesium Supplementation Damage Your Kidney’s?

A: The kidneys play a crucial role in magnesium balance as they control mineral retention and excretion. The evidence is very clear that magnesium is not harmful to normal, healthy functioning kidneys and actually adequate magnesium levels reduce the risk of cardiovascular and kidney disease.1 In fact, studies have shown that chronic kidney disease causes magnesium depletion and lower levels of magnesium increase calcification of blood vessels.1,2,3 Therefore, it is a logical conclusion that magnesium supplementation may protect the vascular damage (calcification) associated with kidney disease but no human clinical trials have been done to confirm.2 It should be noted that in any kidney disease, magnesium supplementation should be supervised by a qualified doctor since there is an increased risk of toxicity as a severe damaged kidney may have trouble eliminating minerals.


  • Massy and Drüeke. Magnesium and cardiovascular complications of chronic kidney disease. Nat Rev Nephrol. 2015 Jul;11(7):432-42.
  • Tran et al. Magnesium: the missing link between kidneys and vessels?. Rev Med Suisse. 2016 Feb 24;12(507):404-7.
  • Kanbay et al. Magnesium in chronic kidney disease: challenges and opportunities. Blood Purif. 2010;29(3):280-92.

Q: Can You Overdose on Magnesium?

A: Hypermagnesia (laboratory high Mg causing toxicity) is a very rare occurrence that hardly ever occurs outside of a hospital setting. In the vast majority of people with healthy functioning organs magnesium (Mg) cannot cause negative effects even with ultra-high doses. Everyone has a bowel tolerance limit where any excess magnesium from supplementation can’t be absorbed and will cause loose stools.

Magnesium can become toxic but that usually occurs in specific disease conditions (i.e. end stage renal disease) where a person has a dysfunction causing excess absorption or is taking an excessive amount of magnesium containing medications (i.e. laxatives).1


  • Kontani M, Hara A, Ohta S, Ikeda T: Hypermagnesemia induced by massive cathartic ingestion in an elderly woman without preexisting renal dysfunction. Intern Med 2005;44:448–452
Dr. Paul Hrkal

About The Author

Dr. Paul Hrkal is a board-certified Naturopathic doctor with a passion to apply innovative and evidence-based nutritional, biological, and supplemental interventions to address underlying metabolic, endocrine and immunological dysfunctions. He is strong advocate of integrative medical education frequently writing and lecturing to both healthcare practitioners and public audiences. He also is the medical director for Advanced Orthomolecular Research, a leading Canadian natural health product company, and maintains a clinical practice in the Toronto area.

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