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  • Dr Laura Stix

Magnesium Deficiency & What To Watch Out For

Magnesium is essential for maintaining normal cellular and organ function. Insufficient magnesium in the body is associated with various disorders, such as type 2 diabetes, metabolic syndrome, elevated C-reactive protein (inflammation), hypertension, atherosclerotic vascular disease, sudden cardiac death, osteoporosis, migraine headache, asthma, and colon cancer.

Because of medications, chronic diseases, decreases in the nutrient content of fresh foods, combined with the availability of refined and processed foods, the vast majority of people in modern societies are at risk for magnesium deficiency. I mention this in The Benefits of Magnesium article.

Possible Signs of a Magnesium Deficiency

How do you know if you're deficient? Well it's not that easy to make a firm diagnosis because of the challenges with lab testing so a good start is to see if you're experiencing symptoms that suggest a magnesium deficiency.

Collated from DiNicolantonio JJ, et al. Open Heart 2018;5:e000668. doi:10.1136/openhrt-2017-000668, here's a reliable summary list of the less and more severe signs and symptoms:

Less severe signs and symptoms:

  • Aggression

  • Anxiety

  • Ataxia (lack of voluntary coordination of muscle movements)

  • Confusion

  • Cramps (spontaneous foot spasm or painful cramps of the muscles in your hands and feet)

  • Disorientation

  • Hyper-reflexia

  • Irritability

  • Muscle twitches (like a flicker of movement under the skin)

  • Muscle weakness

  • Pain or increased sensitivity to pain

  • Photosensitivity (sensitivity to light)

  • Spasticity

  • Tetany (involuntary muscle spasms)

  • Tinnitus (ringing in the ears)

  • Tremors

  • Vertigo

  • Vitamin D resistance

Severe signs and symptoms:

  • Arrhythmias (caused by overexcitation of the heart)

  • Calcifications (soft tissue)

  • Cataracts

  • Convulsions

  • Coronary artery disease

  • Depressed immune response

  • Depression

  • Hearing loss

  • Heart failure

  • Hypertension

  • Migraines/headaches

  • Mitral valve prolapse

  • Osteoporosis

  • Parathyroid hormone resistance and impaired parathyroid hormone release/function

  • Psychotic behaviour

  • Seizures (overexcitation of the nervous system (nerve cells), which are more likely to fire due to a reduced electric potential difference between the outer and inner surfaces of the membrane)

  • Sudden cardiac death

  • Tachycardia (racing heart)

How To Test For Magnesium Deficiency

As mentioned, it's not easy to make a firm diagnosis as there is no simple and accurate laboratory test to determine the total body magnesium status in humans. Normal serum magnesium does not necessarily mean adequate content of total body magnesium, because only less than 0.3% of total body magnesium is found in serum. This means there can still be a deficiency even if the serum reading is normal. It has been noted that even using a cut-off of 0.75mmol/L for magnesium deficiency still misses 50% of those with true magnesium deficiency (the reference range is 0.70 - 1.00 mmol/L).

According to researcher James DiNicolantonio, here are the more reliable (and less reliable) methods of evaluating magnesium status:

DiNicolantonio JJ, et al. Open Heart 2018;5:e000668. doi:10.1136/openhrt-2017-000668

So what's the simple take-home? Research suggests that:

  • People who have symptoms that reflect magnesium deficiency and a serum level below 0.9mmol/L should supplement

  • Anyone with serum levels less than 0.8mmol/L, regardless of symptoms, should supplement

  • Serum magnesium levels above 0.95mmol/L may indicate hypermagnesaemia (too much magnesium) and should not supplement

What To Do About It

When we understand the various factors that can contribute to a low magnesium level we can better navigate which factors may be affecting us and be proactive.

A list follows of a variety of factors to consider, but it's worth highlighting the impact medications can have. Some of the most common medications prescribed in North America are blood pressure medications and antacids (proton pump inhibitors (PPI's) ) and both can have a negative impact on magnesium levels (and often other nutrients as well).

The loop and thiazide diuretics are the type of high blood pressure medications that negatively affect magnesium levels and examples include: Hydrochlorothiazide (Microzide), Metolazone (Zaroxolyn), Indapamide (Lozol), Chlorothiazide (Diuril), Bumetanide (Bumex), Furosemide (Lasix), Torsemide (Demadex), Ethacrynic acid (Edecrin).

Examples of PPI's include omeprazole (Losec), esomeprazole (Nexium), lansoprazole (Prevacid), pantoprazole (Pantoloc), rabeprazole (Pariet) and dexlansoprazole (Dexilant).

There are around 50 medications that can lead to low magnesium levels. Here is a table of the most commonly prescribed medications sourced from Abdullah M. A., Sandawana W.M, and Henrik F. Magnesium and Human Health: Perspectives and Research Directions. Int J Endocrinol. 2018; 2018: 9041694:

This does not mean you should discontinue your medication, but what it does mean is that you may need to take some extra nutrients to ensure you stay repleted, and in this case getting sufficient magnesium is key. Never stop taking your medications without first consulting your healthcare provider.

Here are questions to take into consideration when considering your magnesium status:

  • Are you taking any of the magnesium depleting medications?

  • How much do you sweat? We lose minerals (and some toxic metals), salts and other nutrients when we sweat. Do you frequently exercise? Do you do saunas? Do you do a lot of manual labour?

  • Do you drink reverse osmosis water and if so do you remineralize your water?

  • Do you eat a lot of legumes, grains, nuts and seeds? Though foods are depleted in nutrients, these are the better sources for magnesium (For more information on this, check out this article)

  • Do you do a lot of fasting? About 100mg is lost per day during water fasting.

  • Have you sustained a good deal of physical or mental stress? Stress consumes magnesium and is why people will often complain of a twitchy eye when they're really stressed; stress also causes decreased stomach acid (and reduced magnesium absorption)

  • Do you have some gut issues? Things like IBS, leaky gut, frequent diarrhea, low digestive capacity (remember those PPIs?), celiac disease, or more serious conditions all prevent proper nutrient absorption

  • Do you drink a lot of alcohol? Not only does it impact the gut negatively but it also serves as a diuretic and nutrients are lost

  • Are you pregnant or breast feeding? Both require additional nutrient needs and there are suggested links between magnesium inadequacy and certain conditions in pregnancy associated with high mortality and morbidity, such as gestational diabetes, preterm labor, pre-eclampsia, and small for gestational age or intrauterine growth restriction

  • Do you have diabetes or insulin resistance? Both deplete the body of magnesium (and taking magnesium can improve them)

  • Do you take high doses of Vitamin D on a regular basis or spend lots of time in the sun in the summer? Magnesium is required for the activation of Vitamin D so it gets consumed in the process, plus if you're in the sun you'll likely be sweating and losing even more of it

  • Do you have osteopenia or osteoporosis? Bones store around 60% of total body magnesium and low levels can lead to changes in bone structure, making it more fragile and reducing the blood supply of the bone; magnesium supplements have been shown to improve bone mineral density in osteoporotic women and in young people

  • Do you routinely consume soft drinks or eat a lot of processed foods? A high phosphorus diet (in the form of phosphoric acid and inorganic phosphates) increases depletion of magnesium

  • Do you take calcium supplements without magnesium? Supplementing with calcium can lead to magnesium deficiency due to competitive inhibition for absorption, and taking too much calcium can increase the risk of arterial calcifications

  • Do you take laxatives? These will increase magnesium losses

  • Are you getting older? Of course we all are, however as we age our production of stomach acid declines which means less magnesium absorption; this is one reason seniors are at increased risk of depletion


According to research, most people require an additional 300 mg of magnesium per day in order to lower their risk of developing various chronic diseases.

If there is notable deficiency, one group of authors concluded: ‘When magnesium substitution is started, the minimum dose to be applied is 600mg magnesium per day. The therapy should proceed for more than one month, and then continue with a dose that holds the serum value not lower than 0.9mmol/L magnesium’.

In people who do not have kidney disease it is very unlikely to have excess magnesium levels with reasonable supplementation. Anyone with notable ill health or kidney disease should absolutely seek the help of a healthcare provider before taking any magnesium supplements.


The prevalence of magnesium deficiency is wide-spread and it can present in a variety of ways. Awareness of the key factors that contribute to low magnesium levels can help gauge where some additional support or lifestyle changes may be needed. Maintaining adequate levels in the body is essential to whole body health.


Abdullah M. A., Sandawana W.M, and Henrik F. Magnesium and Human Health: Perspectives and Research Directions. Int J Endocrinol. 2018; 2018: 9041694.

DiNicolantonio JJ, O’Keefe JH, Wilson W. Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis. Open Heart 2018.

Lynne MD, et al. Magnesium in Pregnancy. Nutr Rev. 2016 Sep;74(9):549-57.

Mohammed S. R. Magnesium: Are We Consuming Enough? Nutrients. 2018 Dec; 10(12): 1863.

Reddy P, Edwards LR. Magnesium Supplementation in Vitamin D Deficiency. Am J Ther. 2019 Jan/Feb;26(1):e124-e132.

Rosanoff A, Weaver CM, Rude RK. Suboptimal magnesium status in the United States: are the health consequences underestimated? Nutr Rev. 2012 Mar;70(3):153-64.


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