Which Mistakes Do Most People Make with Magnesium?

Which Mistakes Do Most People Make with Magnesium?

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Magnesium is an essential mineral, which means it's important that you get enough in your diet to stay healthy and that you must get it from dietary or supplementary sources because your body can't make it on your own. It's used throughout the body for processes including muscle function, nerve function, regulating blood sugar, controlling blood pressure, and making new protein, bone, and even DNA. It's also commonly found in everything from fortified cereals to multivitamins and dedicated dietary supplements.

All is not clear and comfortable with magnesium, though, and there's a huge mistake that over half of all people – 52%, to be specific – are making. This mistake may put us at a higher risk of heart attack, stroke, diabetes, and weakened bones. What's going on? Let's talk about it.

The Importance of Magnesium for Your Health

Magnesium, as an essential mineral, is used all throughout the body. It plays a role in over 300 enzyme systems and reactions, including protein synthesis, muscle function, nerve function, blood glucose control, and blood pressure regulation. It's used in the development of bone, in the synthesis of DNA, and in the production of glutathione, which is a powerful antioxidant.

Magnesium Supplements

Magnesium is also used in the transport of calcium and potassium ions across cell membranes, which is a crucial part of how nerve impulses work, how muscles contract, and even how your heart maintains a regular rhythm.

Magnesium levels in the body can be checked with a blood test, but there's a problem with these tests. In fact, even if you're measured to be within normal ranges, you might still be deficient.

The Problem with Magnesium Blood Testing

Since magnesium is used all throughout the body, it's also stored all throughout the body. A typical healthy adult has around 25 whole grams of magnesium, but over half of that is stored entirely in the bones. Most of the remainder is stored in soft tissues. In fact, less than 1% of your body's magnesium is present in the blood.

More importantly, your body is very good at regulating exactly how much magnesium is allowed to be in the blood in the first place. If blood magnesium levels drop too far, your body will pull magnesium from other tissues or bones and put it into circulation. Similarly, too much magnesium in the blood means your body will siphon some of it to stash away in case a later need for it arises.

Magnesium Blood Testing

Basically, this means that your blood magnesium levels are almost always going to be within normal ranges because it's the last place magnesium is stored to fall out of balance. You can be deficient in your bones and soft tissues, and your blood can still show normal ranges of magnesium.

So, wait. If we know this, why don't we develop another test? The truth is, we have. There are several other tests, including both saliva and urine tests. The trouble is, none of them are considered reliable and satisfactory enough to accurately measure magnesium intake.

The Potential Benefits of Magnesium

Another question it's always good to ask is whether or not it's effective to supplement a nutrient in the first place. There are, after all, many cases where taking more of a given nutrient in your diet just means your kidneys will filter it out, and it'll pass right through you. Is magnesium one of these? Let's look at some studies.

The first study comes from 2010. It was an observational study of over 14,000 individuals, using data from a different study called ARIC. It showed that higher magnesium intake was associated with a nearly 40% reduction in sudden cardiac death.

A Person Holding Magnesium Supplements

Another study in the American Journal of Clinical Nutrition studied over 300,000 people. It showed that higher magnesium levels were associated with a 30% lower risk of heart disease.

A similar report of the same association, showing low magnesium levels associated with a 36% higher risk of heart death compared to those with higher levels of magnesium, can be seen in some very compelling graphs from the Journal of the American Heart Association in a similar study of their own.

There's more.

  • A study from 2012 reviewing over 240,000 cases showed that higher magnesium intakes were associated with a lower risk of stroke.
  • A study of over 500,000 people from 2011 showed higher magnesium levels are associated with a 22% reduction in the risk of developing Type II diabetes.
  • Further studies throughout the industry have shown similar associations between higher magnesium levels and better outcomes with everything from dementia, Parkinson's, depression, anxiety, and even poor hearing.

There's one significant problem here. You may have caught it in all of the examples I've given you.

The Problem with Magnesium Studies

"Is associated with."

This is a correlation, and as we all know, correlation does not equal causation.

  • There's a strong correlation that the more movies Nicholas Cage stars in, the more people who fall into swimming pools will drown.
  • There's a strong correlation between the amount of global cheese consumption per capita and the number of people dying tangled in their bedsheets.
  • There's a strong correlation between the number of UFO sightings in Rhode Island and the number of successful climbs of Mount Everest.

In fact, there's an entire website dedicated to these kinds of correlations, called spurious correlations. Things that have similar trends and data points, but which are clearly, by any logic, completely unrelated.

A Handful of Supplements

This is what happens when your studies all come from observation of data from other study groups. These kinds of observational studies are the easiest way to get huge amounts of data, but they aren't seeking cause and effect; they're just observing trends. That doesn't mean they're wrong; they are just not necessarily right in their conclusions.

The proof needs to come from human trials with randomized, double-blind, controlled trials. There are, unfortunately, very few of these, especially the appropriate kind of long-term trials necessary to prove long-term health outcomes like the risks of cardiac death. Fortunately, "very few" doesn't mean "none."

The downside here is that many of these trials have had conflicting results. One trial from 2018 showed that magnesium supplements had benefits for metabolic syndrome, but another trial studying the same thing did not. This is reflected throughout the industry, with conflicting trials on everything from sleep quality to muscle cramps.

Make no mistake: your body needs magnesium. Without it, many different systems start to break down. But, beyond basic function, there just isn't much evidence beyond correlations to associate higher magnesium intake with beneficial health outcomes. Those correlations, again, aren't necessarily inaccurate, but they may not be causative.

Dietary Magnesium and Supplements

The key takeaway here is that you need at least a certain minimum daily intake of magnesium to stay healthy. The recommended daily intake is 320 mg for females and 420 mg for males. Unfortunately, some 48% of people aren't reaching this average or even the typical minimum intake. Many of these people see normal levels of magnesium in their blood tests and assume they're getting enough when they aren't.

You can get magnesium through a healthy diet. Foods like spinach, legumes, nuts, seeds, and whole grains are rich in magnesium, as is just about anything with good dietary fiber. Meat has some, but not nearly as much.

Unfortunately, you can probably see where this is going. Our society is structured to provide cheap, fast, mass-produced, and processed foods as the easiest options. It's a lot easier to grab a boxed meal than to cook one yourself, right? Unfortunately, this act of processing often strips a lot of the micronutrients you need from those foods, and while some foods fortify nutrients back in, they don't always get enough of everything they lost.

A Person Taking a Magnesium Supplement

Some people turn to the easy solution:start taking supplements. That's fine if your diet is otherwise healthy, but you aren't quite reaching appropriate recommended daily intake levels because of portion sizes or other dietary restrictions. But, if you're relying on processed foods, fast foods, and other less healthy sources, you're missing out on more than just the specific micronutrient like magnesium you're targeting.

I like to use myself as an example. I keep to a very healthy diet, but occasionally my diet may not give me the recommended daily intake of magnesium. Some days I hit it, some days I don't; that's just how it goes; there's no such thing as a perfect meal. So, through MicroVitamin, I take an added 126 mg of magnesium each day, which is about 30% of the RDI. That's what I've developed for myself; you should evaluate your own diet and talk with your own health specialists to determine what's right for you. You may have adequate magnesium intake already!

What Kind of Magnesium is the Best?

Something I mentioned above is that some supplements aren't really bioavailable and tend to just pass through you when you take them. Your body is generally pretty good at ignoring or filtering out things it doesn't need, but there are also some forms of certain nutrients that chemically lock them up and make them harder for the body to access. This is frequently the case with different forms of the same nutrient; chemical structures and forms can vary, and some are more or less bioavailable than others.

So, let's look at the different forms of magnesium you might find on store shelves and figure out which one is best.

A Doctor Holding a Supplement

The first is Magnesium Oxide. Magnesium oxide is the cheapest form, and thus the most readily found, but it's also the least bioavailable form. It's actually becoming less common on store shelves simply because it's the least effective, and market pressure from more effective – if slightly more expensive – versions is driving it out.

Magnesium Citrate is probably the second most common form of magnesium you'll find. It's more bioavailable by a significant margin. The downside is that it tends to have a strong laxative effect, so much so that it's commonly sold as a laxative. This is a side effect, but it's not necessarily a pro or a con; different people have different bowel habits, and some will benefit from magnesium citrate while others will not.

Another form is Magnesium L-Threonate. This one has been getting some attention recently due to some animal studies that seem to show positive benefits for sleep, memory, and cognition. Human studies have had conflicting results. If you're interested, I did a deeper dive into Magnesium L-Threonate here.

My favorite forms of magnesium are the forms bound to amino acids rather than to other minerals. Two such options are magnesium glycinate and magnesium taurate. I prefer taurate, but they're both good, well-absorbed and have lower side effects.

What to Watch For in Magnesium Supplements

The recommended daily intake of magnesium – 320 mg for women and 420 mg for men, in otherwise healthy adults aged 30 and up – is based on elemental magnesium. That is pure magnesium. Magnesium that is bound to another nutrient, which is basically every supplemental source of magnesium you can find, is only partially magnesium.

Take magnesium taurate, for example. The average magnesium taurate supplement is actually only 8-9% magnesium. MicroVitamin for example, contains over 1,500mg of Magnesium Taurate to reach the 126 mg amount of elemental magnesium.

Supplement-makers know this, which is why you often see serving sizes of 4-5 pills per day for these supplements. So, keep that in mind.

Magnesium Supplement Pills

Finally, I want to leave you off with a pretty shocking fact that blew my mind when I first learned it. It ties into why so many people struggle to get enough magnesium in their diets when that didn't used to be the case.

Magnesium used to be in the water.

Over time, though, as we've progressed towards more unified city water supplies, with greater levels of water treatment to avoid water that's either too "hard" or too "soft", we strip a lot of the minerals present in that water. A study in Israel found that magnesium levels fell sharply when they switched to desalinated seawater, which is heavily treated, for example.

Wild, right?

It puts a heavier burden on a healthy diet, one of the three core pillars of overall health. A supplement can help, but make sure you know what your dietary intake is, whether or not you're getting enough, and what the best option is for you to supplement more to your diet.


  1. Magnesium Fact Sheet for Health Professionals: https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
  2. Serum Magnesium and Risk of Sudden Cardiac Death in the Atherosclerosis Risk in Communities (ARIC) Study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2939007/
  3. Circulating and dietary magnesium and risk of cardiovascular disease: a systematic review and meta-analysis of prospective studies: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683817/
  4. Serum Magnesium and the Risk of Death From Coronary Heart Disease and Sudden Cardiac Death: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4859391/
  5. Dietary magnesium intake and risk of stroke: a meta-analysis of prospective studies: https://pubmed.ncbi.nlm.nih.gov/22205313/
  6. Magnesium intake and risk of type 2 diabetes: meta-analysis of prospective cohort studies: https://pubmed.ncbi.nlm.nih.gov/21868780/
  7. Oral Magnesium Supplementation and Metabolic Syndrome: A Randomized Double-Blind Placebo-Controlled Clinical Trial: https://pubmed.ncbi.nlm.nih.gov/29793665/
  8. Magnesium for muscle cramps: https://www.cochrane.org/CD009402/NEUROMUSC_magnesium-muscle-cramps
  9. Seawater desalination and serum magnesium concentrations in Israel: https://pubmed.ncbi.nlm.nih.gov/28362310/

About Dr. Brad Stanfield

Dr Brad Stanfield

Dr. Brad Stanfield is a General Practitioner in Auckland, New Zealand, with a strong emphasis on preventative care and patient education. He runs a YouTube channel with over 240,000 subscribers, where he shares the latest clinical guidelines and research to promote long-term health. Dr. Stanfield is also involved in clinical research, having co-authored several papers, and is a Fellow of the Royal New Zealand College of General Practitioners.

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