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Magnesium Deficiency: How Common Is It, and How Would You Know?

A magnesium result on a Swedish lab report arrives as one number, usually somewhere between 0.75 and 0.95 millimoles per litre, and in most cases it lands inside that interval. The number is real and the laboratory measured it accurately. What it measured is less than one percent of the magnesium in your body.

That single fact explains most of the confusion around magnesium deficiency. A poor test invites two opposite mistakes: trusting a normal value completely, or assuming that everyone must be short. This article steers between them, and ends with what the answer meant for how we at Health Royals built a daily supplement.

Which magnesium salt a product uses, and how much elemental mineral sits behind the number on the box, is a separate question, covered in magnesium forms, absorption and what a label actually tells you.

Health Royals Peak Performance, supplement with vitamin D3, K2 as MenaQ7, folate as Quatrefolic and omega-3 from algal oil

The everyday foundation at Health Royals

For everyday life we chose a broader foundation than a single mineral. Peak Performance Formula is our daily multivitamin for women, with omega 3 from algae, D3, K2, B vitamins, zinc, selenium and Extramel®, the melon extract used in two placebo-controlled human studies that measured perceived stress, fatigue and sleep-related problems. Vitamin B12 and folate contribute to the reduction of tiredness and fatigue.

See Peak Performance, multivitamin for women with omega 3

What counts as magnesium deficiency?

Formally, a serum magnesium concentration below 0.75 millimoles per litre. That threshold is both the standard definition and the most debated part of it.

The normal serum range is usually given as 0.75 to 0.95 mmol/L, and a value below 0.75 is considered low.

The scoping review written for the Nordic Nutrition Recommendations 2023, by Christine Henriksen and Jan Olav Aaseth, is more careful. Concentrations below 0.75 mmol/L identify severe deficiency, while individual levels between 0.75 and 0.85 may be suboptimal and need further evaluation, in the published review. That grey zone sits inside what a lab report calls normal.

A 2022 paper in European Journal of Nutrition by Andrea Rosanoff, Christina West, Ronald Elin and colleagues goes further and recommends raising the lower reference value to 0.85 mmol/L, because, they argue, the populations behind the reference ranges include people with chronic latent magnesium deficit. Their recommendation has not been adopted by EFSA or the Nordic recommendations, and Swedish healthcare still works to 0.75. The line is a measurement convention, not a point at which anything decisive happens in the body.

Why is a blood test a poor measure of magnesium?

Because blood holds less than one percent of the body’s magnesium, and the body works hard to hold that one percent steady whatever is happening to the rest.

An adult body contains roughly 25 grams of magnesium. Jayme Workinger, Robert Doyle and Jonathan Bortz broke the distribution down in Nutrients in 2018: 0.3 percent in serum, 0.5 percent in red blood cells, 53 percent in bone, 27 percent in muscle and 19 percent in other soft tissue. The tightly controlled serum concentration, they write, serves as a poor proxy for the 99.2 percent of magnesium in other tissues that constitutes the body’s true magnesium status, in Challenges in the Diagnosis of Magnesium Status.

When intake falls, the kidney lets less magnesium go and the exchangeable pool in bone and soft tissue is drawn on to hold the serum concentration where it is, so the stores can fall while the blood value stays inside the interval. A normal magnesium value therefore shows that your kidneys and your skeleton are doing their job of holding the blood level steady. It measures that balance rather than your stores, which is a reason for care, not for assuming the worst.

Is there a better test than serum magnesium?

There are several candidates, and none of them has been agreed on.

Red blood cell magnesium is the alternative most often recommended online, and it covers 0.5 percent of body magnesium against 0.3. Workinger and colleagues note that validating it would require roughly three months on diets deliberately replete or deplete in magnesium, and that too few such studies exist. Urinary magnesium is weaker still, because renal reabsorption and excretion fluctuate widely. The magnesium loading test, which measures how much of an infused dose is retained, is the closest thing to a functional test that exists, and nobody runs it in primary care.

Rebecca Costello and Forrest Nielsen reviewed the same problem in Current Opinion in Clinical Nutrition and Metabolic Care in 2017 and landed on a compromise: serum magnesium, 24 hour urinary excretion and dietary intake read together are currently the most practical way to assess status, and people with serum values between 0.75 and 0.85 mmol/L alongside other low indicators may be deficient, in Interpreting magnesium status to enhance clinical care.

The Nordic Nutrition Recommendations 2023 put the position in one sentence in the magnesium chapter: no adequate functional biomarker of magnesium status has been identified. Intake data and prevalence figures tell us more than the test does.

How much magnesium do people in Sweden actually get?

On average, slightly more than the reference value, which says something about the population and nothing about you.

Riksmaten vuxna 2010 to 11, Livsmedelsverket’s national dietary survey, recorded food intake for 1 797 adults aged 18 to 80, in the published report. Livsmedelsverket’s own analysis, by Wulf Becker and Irene Mattisson, reports a mean magnesium intake of 364 mg a day for men and 305 mg a day for women, and notes that mean intakes of calcium, potassium and magnesium were at or above the Nordic recommendation, in a 2016 Livsmedelsverket analysis.

The current reference values are 350 mg a day for adult men and 300 mg a day for adult women, in the Nordic Nutrition Recommendations 2023 as reproduced by Livsmedelsverket and in EFSA’s 2015 scientific opinion on dietary reference values for magnesium. They are adequate intakes rather than average requirements, so comparing a population mean to them is a weaker exercise than it looks. A mean also says nothing about the tail, and neither the Riksmaten report nor the Nordic chapter publishes a share of Swedish adults below the adequate intake, so nobody can say how many Swedes get too little.

What the same survey does flag is more useful. The nutrients where Swedish intakes more often fall below the reference values are not magnesium but vitamin D, folate and iron, with selenium as a fourth, and we have gone through those figures in what Riksmaten does and does not show about nutrient intakes in Sweden. That contrast is the one we return to at Health Royals when deciding what belongs in a daily supplement: not which mineral is discussed most, but which nutrients the intake data point at.

Who actually runs low on magnesium?

Mostly people with an illness or a medicine that makes them lose it.

The Nordic magnesium chapter says it in a line: magnesium depletion is uncommon and usually secondary to a disease or to the use of a therapeutic agent. A review of hypomagnesaemia in StatPearls gives a prevalence of 2.5 to 15 percent in the general population, 12 to 20 percent among hospitalised patients and around 65 percent in critically ill patients. The gradient tracks illness, not diet.

The groups at risk are people with gastrointestinal disease with malabsorption, such as Crohn’s disease and coeliac disease, type 2 diabetes, alcohol dependence and older age. StatPearls adds inherited renal tubular disorders, loop and thiazide diuretics, and proton pump inhibitors.

A systematic review and meta-analysis by Chan Hyuk Park and colleagues in PLOS ONE in 2014, covering nine studies and 115 455 patients, found a pooled odds ratio of 1.775 for hypomagnesaemia among proton pump inhibitor users, in the published meta-analysis. All nine studies were observational and differed widely, so this is an association worth raising with a doctor, not a settled causal quantity.

Can you recognise magnesium deficiency from the symptoms?

No. The early symptoms are shared with almost every other common complaint.

StatPearls lists the early features as nausea, weakness and fatigue. The findings that actually point at magnesium, neuromuscular hyperexcitability, tremor, tetany and in severe cases cardiac arrhythmia, appear well below the diagnostic threshold, typically under 0.5 mmol/L, in people who are usually already visibly unwell.

Workinger and colleagues make the same point in one sentence: magnesium deficiency does not present with unique and identifiable clinical manifestations. A checklist of tiredness, poor sleep, muscle tension, cramp and low mood will return a positive result for most adults in a Swedish February. Such lists are effective marketing and poor diagnosis.

What does the evidence show about magnesium in Sweden?

The intake data and the prevalence figures point the same way: magnesium deficiency is uncommon in Sweden, and where it occurs it has recognisable causes.

Two statements get run together. The first, that serum magnesium is a poor measure of total body magnesium, is well established. The second, that most people are therefore deficient, does not follow. A weak test is an argument for uncertainty, not for assuming the worst case, and the intake data and the prevalence figures both point the other way.

Swedish intake reaches the reference value on average. On health outcomes, the Nordic scoping review concluded that the evidence suggests a causal relationship between magnesium intake and reduced risk of cardiovascular disease, hypertension and metabolic syndrome, and improvement of glucose tolerance, while noting that observational data cannot separate magnesium from the whole grains, legumes, nuts and vegetables that carry it. Magnesium in food is worth having, and food is where most people get it.

Magnesium has several authorised health claims in the EU, listed in the annex of authorised health claims to Commission Regulation (EU) No 432/2012; they describe what the mineral does in a body that has enough of it. The same gap between a laboratory threshold and a meaningful one runs through vitamin D in a Swedish winter.

When is a magnesium supplement relevant, and what do we recommend for everyday life?

A magnesium supplement is relevant when you have a reason to lose the mineral, and then it is a question for a doctor before it is a question for a shelf.

If you have one of the conditions or medicines listed above, a high alcohol intake, or you are older and eating less overall, that belongs in a conversation with a doctor. It is also the one situation in which serum magnesium performs well, because clinically significant depletion is precisely what the test was built to catch.

If you decide to supplement anyway, know the ceiling. The EU Scientific Committee on Food set a tolerable upper intake level of 250 mg a day for magnesium from supplements, water and fortified food, excluding the magnesium naturally present in food, based on mild diarrhoea, in its 2001 opinion on the tolerable upper intake level of magnesium. Which salt delivers that dose, and how much of the number on a label is elemental magnesium, is the subject of magnesium forms, absorption and labels.

For everyone else, the intake data suggest food is already doing the work: magnesium sits in whole grains, legumes, nuts, seeds and leafy vegetables. For everyday life we recommend a broader foundation instead. Our starting point at Health Royals is fewer jars and more thought: a daily supplement should be built around the nutrients the intake data point at, not around whichever mineral is being talked about most.

This is where Peak Performance comes from. Rather than magnesium, it is built around nutrients the intake data point at, vitamin D3, 25 µg, folate, 200 µg, as Quatrefolic® 5-MTHF, and selenium, 27.5 µg, together with the omega 3 that most multivitamins leave out: OMEGATEX® algal oil, 500 mg, giving 375 mg omega 3 of which 300 mg DHA and 50 mg EPA. Iron is left out on purpose, because for women of fertile age it is a question for a blood test and a doctor rather than a multivitamin. Around them sit vitamin K2, 90 µg, as MenaQ7®, vitamin B12, 10 µg, as MecobalActive® methylcobalamin, thiamin 1.1 mg, niacin 16 mg, chromium 20 µg and zinc 5 mg as L-OptiZinc®, together with two plant extracts: Hytolive® olive fruit extract, 150 mg, giving 15 mg hydroxytyrosol, with 450 mg extra virgin olive oil, and Extramel® melon extract, 10 mg, a source of superoxide dismutase.

The doses follow a rule we apply across the range. The two plant extracts sit at the dose used in their human studies: Hytolive at the 15 mg of hydroxytyrosol a day used in the randomised, double-blind, placebo-controlled human study on the material, and Extramel at the 10 mg a day used in the two placebo-controlled human studies on it. The vitamins and minerals sit at a nutritional level, close to the reference intakes. For us, the ingredient cannot be separated from its source, manufacturer and studied dose. Health Royals works with specialist manufacturers, researchers and supplier networks to select them.

Sleep deserves its own paragraph here, because it is the reason many people start reading about magnesium in the first place. The ingredient in Peak Performance with human data closest to that question is Extramel. In a randomised, double-blind, placebo-controlled pilot study published in Nutrition Journal in 2009, 70 healthy adults aged 30 to 55 with everyday stress and fatigue took 10 mg of Extramel or placebo daily for four weeks, and the Extramel group reported a 38 percent greater improvement in sleep-related problems than the placebo group, along with 12 percent for perceived stress. A second placebo-controlled study of 61 adults over 84 days, published in Nutrients in 2014, reported lower perceived stress and lower physical fatigue. Both studies measured these outcomes with questionnaires, at 10 mg of Extramel a day, and Peak Performance contains the same 10 mg. We go through both studies in our article on SOD from melon.

It comes in an amber glass jar with a scent core, made to stand on a shelf and become part of the morning, and the subscription sends the jar once and refill pouches after that, two jars a year instead of twelve.

What is worth doing about it?

Start by deciding whether you have a reason to suspect a problem at all, then act on that answer rather than on a symptom list.

  • If you have a condition or a medicine on the list above, ask a doctor to look at magnesium. A serum test performs well for the depletion that matters clinically.
  • If none of that applies, treat a normal serum value as normal and let food carry the mineral.
  • If you supplement magnesium anyway, stay at or below 250 mg a day from supplements and read the label for elemental magnesium, not the weight of the salt.
  • If tiredness is the question, do not let magnesium be the only nutrient you consider. Vitamin D, folate and iron are the ones Swedish intakes more often fall short on.

For those nutrients the EU has authorised health claims. Vitamin D contributes to the normal function of the immune system and to normal muscle function. DHA contributes to the maintenance of normal brain function, a claim that applies at 250 mg of DHA a day. Niacin and vitamin B12 contribute to normal energy-yielding metabolism, and niacin, folate and vitamin B12 contribute to the reduction of tiredness and fatigue.

Broader context on the nutrients Swedish adults actually run low on sits on our wellbeing page.

We have done the selection so that you do not have to. Peak Performance is one jar, built around vitamin D, omega 3 and folate with the vitamins, minerals and two plant extracts listed above, at doses we publish and can explain. If magnesium turns out to be your question, this article has told you how to find out. If it is not, you can stop looking.

Further reading

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