Magnesium Deficiency Is Linked to Sudden Cardiac Death

Heart disease is the leading cause of death in the U.S. While coronary heart disease rates have fallen by around half in the decades from the early 1970s to today, the incidence of sudden cardiac death remains a significant fraction, nearly three quarters, of all heart disease deaths. That fraction increases when considering men under the age of 45. Magnesium deficiency is linked to sudden cardiac death.

Sudden Cardiac Death

Sudden cardiac death (SCD) is said to occur when someone has an unexpected heart attack or arrhythmia or other heart problem and dies within one hour of the event. The truly scary thing about SCD is that the majority of victims have no prior symptoms of heart disease. While they do often have risk factors, notably obesity, hypertension, and a history of smoking cigarettes, the onset of SCD is truly sudden. Essentially what happens is that one fine day the SCD victim just collapses and dies without having any inkling of what might be wrong. By the time they get to the hospital it’s usually too late.

In 1998, there were over 450,000 cases of SCD in the U.S. SCD is a major public health problem; despite all of the advances in cardiac medicine, as well as vastly increased knowledge of how to prevent heart disease, hundreds of thousands of people die from SCD annually, and this problem is particularly acute among men.

Risk Factors

As mentioned, risk factors for SCD include obesity, hypertension, diabetes, and smoking. If you’re reading a health and fitness blog like this one, you likely either don’t have these risk factors or are working to bring them under control. Frankly, most people who do have these risk factors don’t care enough about their health to do anything about them.

But there is another risk factor that many, even the most health-conscious, are unaware of, and that is their magnesium level.


Magnesium is an essential element that is required for over 300 enzymatic reactions in the body, and is particularly important in energy production. Muscles function poorly when magnesium levels are low, and it will not escape notice that the heart is a muscle. Low magnesium levels can lead to arrhythmias.

Importantly, magnesium deficiency is widespread in the U.S., with up to 70% of people failing to consume the RDA. The high level of deficiency centers around two causes: one, the use of processed food, which is low in magnesium; and the abandonment of drinking hard water, which is abundant in magnesium. Locations in which people drink hard water are associated with lower rates of sudden cardiac death.

Magnesium deficiency is linked to sudden death.

(1) Sudden death is common in areas where community water supplies are Mg-deficient. (2) Myocardial Mg content is low in people who die of sudden death. (3) Cardiac arrhythmias and coronary artery vasospasm can be caused by Mg deficiency and (4) Intravenous Mg reduces the risk of arrhythmia and death immediately after acute myocardial infarction.

Magnesium levels are strongly and negatively correlated with rates of SCD, even after adjusting for other risk factors. In a prospective study, those who were in the highest quartile of magnesium level had a nearly 40% reduced risk of SCD. What is more, the paper that found this specifically recommends looking at magnesium supplementation in order to prevent SCD.

Even if you eat a diet consisting mainly of whole foods, you’re likely not drinking hard water and could very well be magnesium deficient. A serum magnesium level will tell you something about your magnesium levels, but it’s not the whole story, since most magnesium is stored inside cells, little of it is in the serum, and the body strives to hold serum magnesium levels within a fairly narrow range. So a blood test for magnesium can be misleading, although low levels probably do show an overall deficiency.

Personally, I take a supplement consisting of 200 mg magnesium daily, and I’ve done this for the past six or seven years. I take it right before bed, since magnesium promotes relaxation and may improve sleep because of this.

Deficiency can take some time, perhaps months, to completely overcome when supplementing with magnesium, since the cells will remove it from the blood to use for their own purposes. If you’re interested in the complete story on magnesium and how it affects health, I recommend the book by Carolyn Dean, M.D., The Magnesium Miracle, which tackles the subject in great detail. (And of course you might try my own book on supplements for men, which covers magnesium.) I credit magnesium with a large role in my return to health. Some of my readers have told me about their experiences with magnesium in terms that validate Dr. Dean’s use of the word “miracle”.

The common form of magnesium seen in drugstores and the like, magnesium oxide, is very poorly absorbed from the gut, with some reports showing zero change in magnesium levels after a course of it. Magnesium citrate is available at Amazon (that’s an affiliate link, no extra cost), is nearly 100% absorbed, and is the kind I use.

So, don’t become a victim of sudden cardiac death. Ensure that your magnesium levels are up to snuff, and that your other risk factors are under control, and you won’t. If you do have these other risk factors, and are unable to get them under control, magnesium could mean the difference between life and death.


PS: Those with kidney disease should consult a doctor before supplementing with magnesium, as this could cause a potentially toxic accumulation of magnesium. For everyone else, magnesium generally has very low toxicity and no side effects. The RDA is ~400 mg for an adult man, so supplementing with 200 mg is a moderate dose.

PPS: Check out my Supplements Buying Guide for Men

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Leave a Comment:

Justin Irving says March 2, 2015

The only downside is that these tablets are on the big side. I switched to taking Natural Calm powder (though NOW also makes a powder) as I started to develop are real aversion to taking the tablets. Can’t choke to death on powder.

    P. D. Mangan says March 2, 2015

    Agree, they’re pretty huge. I don’t have a problem with them myself.

jrm says March 2, 2015

Why do you keep recommending oral magnesium supplementation? It causes diarrhea in lots of people.

The best way to supplement magnesium is to soak the feet in a very saturated solution of magnesium chloride (epsom salt aka magnesium sulfate also works, but not as well). Getting magnesium through the skin bypasses digestive tract issues.

    P. D. Mangan says March 2, 2015

    200 mg of mag citrate should not cause diarrhea in anyone, and it never has for me. The type of magnesium that is used to treat constipation, such as milk of magnesia or epsom salts (magnesium sulfate), is poorly absorbed and works by attracting water into the gut by osmosis. Mag citrate doesn’t do that.

    As for soaking in magnesium chloride, that can work, but the problem is you don’t know how much you’re getting. It could be a lot and, while magnesium generally has very low toxicity, too much could be a problem, especially in those who have kidney disease. Or it could be too little, in which case you’re not really supplementing at all.

Remnant says March 3, 2015

Off topic: Dennis, you have written a lot about various things men can do to increase testosterone — diet, weightlifting, AIs, Vitamin D, etc. — however, to my knowledge, you have not written much on, or directly discussed, TRT. Is that something you would do a post on, whether generally on the science or to discuss any experience you might have with it? It’s something I am debating myself over, and although my instinct is to “stay natural”, sites like Jay’s, Danger & Play, and Bold & Determined are increasingly convincing me that my reluctance may be unwarranted.

    P. D. Mangan says March 3, 2015

    I could write something on that, and maybe the only reason I haven’t is because the other sites you mentioned have covered the topic well and have more experience with it. Jay, for instance, has probably forgotten more than I’ll ever know on TRT. Assuming that you could benefit from TRT, I also think that there’s not that much point to staying “natural”, since if you decided for some reason to discontinue it, everything goes back to normal in a short while, no harm whatsoever done.

      Remnant says March 3, 2015

      Thank you for this response, Dennis, as well as the extremely informative post you just put up about your experience with AIs.

      I don’t think there is anything magic about “staying natural” but there is a psychic barrier I have to putting a needle into myself for the rest of my life: and yes, one can go off TRT but pretty much everyone who recommends it (Jay, Mike, Victor) makes it sound like a one-way path: once you try it, you never go off it. Granted they say that is because your life is so much better with it that you wouldn’t want to, but I am still a bit wary of taking that step yet.

      Even before I read your latest post, I was interested in AIs as a possible alternative, and I now think that may be the way to go if my levels are appropriate. Next step is to get tested. Thanks again!

BigFatGuy says March 3, 2015

Magnesium sure cured my insomnia. It was amazing! Has to be magnesium citrate, though. The stuff from Walmart doesn’t work. Also, I had to take it for a few weeks before I noticed the change in my sleep.

I only started taking supplements like magnesium and NAC because Dennis told me to. I never thought they would actually do anything. 🙂

Eric Astrauskas says March 14, 2015

Magnesium deficiency is becoming an epidemic. This is just another reason why we need to start being concerned. I try to include raw cacao in my daily diet to boost my magnesium levels. The main reason for trying to get in more magnesium was for skeletal muscle recovery post-workout and for relaxation. Thanks for this information… I will relay it to my personal training clients.

Neil says June 28, 2015

My bro died in 2011 from heart attack suddenly, I have been feeling deathly lately, I’m his age at time if death 45, he was 44, I remember he was always tired near his end, as I have been. So I tried magnesium last night and already feel much more awake than in weeks, I wonder now if my bro had a deficiency. I read cortisol uses up magnesium and both his death and my situation now are high stress.

Gnarl says October 8, 2015

Magnesium citrate is a laxative. Around 100mg is alright at a time for me, but i if i take more i definitely get laxative issues. What do you think of other forms such as glycinate, succinate, etc?

The magnesium you recommend also contain magnesium stearate, which ive heard some bad stuff about.

    posthasty says October 8, 2015

    Magnesium glycinate is the most highly absorbed oral form I’ve found. No laxative effects at a standard 400 mg dose.

Why Resting Heart Rate Is Important for Health - Rogue Health and Fitness says August 24, 2016

[…] of the mechanisms, as do previous studies showing a particularly strong effect of elevated RHR on sudden cardiac death. [Link […]

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