Magnesium under the Microscope

{Ten minute reading time}

Magnesium may not have the same reputation as its well-advertised mineral counterparts calcium and iron, but it is no less significant to health. It plays physical roles in structures as fundamental as chromosomes, cell membranes and bones, and it is required for hundreds functions in the body [1]. Consequently, health problems considered to relate to magnesium deficiency range from insulin resistance, coronary heart disease and hypertension, to migraines, osteoporosis [2] and inflammatory bowel disease [3]. Unfortunately, there are factors that limit magnesium availability and absorption, meaning the majority of Westerners is technically magnesium deficient. In previous posts you have been introduced to sources of magnesium in food, transdermal applications and mineral water and in order to help you get the magnesium you need. In this post, you’ll find out more about magnesium and its roles in the body, health and disease.

What functions does magnesium perform in the body?

Energy and metabolism

Adenosine triphosphate (ATP) is a molecule that provides the energy for virtually all metabolic processes, but in order to be biologically active, it exists as a magnesium complex (MgATP). This helps to explain why magnesium is needed by over 300 different functions in the body. Magnesium is also essential to the digestive enzymes that enable the metabolism of lipids and carbohydrates, which in turn, provides the body with energy.  [1].

Muscle contraction and relaxation

As previously mentioned, ATP exists primarily as MgATP. This molecule is crucial to the chemical actions regulating muscle contraction and relaxation [1]. Without it, the body is prone to muscular tightness and spasm.

Nerve impulse conduction

Magnesium is needed to transport other ions (e.g. Ca+, Na-) across cell membranes, thus playing a crucial role in the transmission of nerve impulses throughout the body, including impulses affecting normal heart rhythm.

More vital functions

Magnesium is required in the chain of reactions that enables parathyroid hormone secretion, and therefore is involved in calcium regulation. It is also involved in the synthesis of the antioxidant glutathione- a constituent of almost every cell in the body and with the role of alleviating oxidative stress and inflammation, i.e. keeping cells healthy. In the cells, magnesium is also required for the production of deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and other proteins. There is speculation, too, that magnesium is needed for wound healing due to the influence of extracellular magnesium on cell migration [1].

The scope of magnesium’s importance to systemic health or dysfunction is due to its involvement in activities of cell replication, cell building, cell maintenance and intra-cellular communication, as well as its roles in enzyme functions and endocrine homeostasis. Magnesium really is THE multitasker of the body.

How much magnesium do I need?

Normal blood (serum) magnesium concentrations range between 0.75 and 0.95 mmol/L. These levels are both tightly and largely controlled by the kidneys, which, typically excrete 120 mg of magnesium into urine daily [4]. Serum magnesium, however, makes up only 1% of magnesium in the body and is considered a poor indicator of magnesium status. Interestingly, well over 50% of magnesium is present in bones and the rest is found in muscles and soft tissues including brain tissue [5].

For women aged over 30 years, the Australian NHMRC estimates an average requirement of 265mg per day and recommends a daily intake of 320mg, as not all the magnesium will be absorbed [4]. The values are higher for pregnant women and younger women and for men.  More information is available online at the Nutrient Reference Values website.

The United States’ NIH provides a tolerable upper limit for women of 350mg of magnesium in the form of supplements. Large doses of oral magnesium supplements and magnesium based medications can result in diarrhoea, nausea and abdominal cramping [2] and indeed, magnesium can be the major constituent of laxative medications. The NIH clarifies that consuming larger amounts of magnesium from food sources does not pose these same risks, because healthy kidneys are able to regulate the excess through urine output [2] presumably due to the more incremental metabolism of magnesium in food. From this point of view, sipping a soluble magnesium supplement throughout the day is preferable to taking large single doses provided by tablets [6].

How do I know if I am magnesium deficient?

No single test is considered sufficient for testing magnesium levels.  Serum magnesium at less than 0.75mmol/L is termed hypomagnesaemia (low blood magnesium). It is more commonly seen in intensive care units or in elderly people with kidney disease.  It is a serious condition- left untreated, it has life threatening consequences [3].

There is research suggesting that in order to preserve vital serum levels of magnesium, the body may redistribute magnesium from bones, muscles and tissues to the blood, when magnesium is in short supply. The inference is that when serum magnesium levels sit with in the normal range, the tissues may be experiencing deficiency [6]. (See also the summary at the end of this post.)

Confounding factors

One confounding factor in magnesium deficiency is that our food sources have also become less abundant in magnesium due to changes to agriculture that have involved the development and mass planting of high-yielding, fertiliser-dependent grain crops. These methods have reduced the content and availability of magnesium in the soil. Researchers found that before 1968, there were on average 115–126mg/100g of magnesium in (dry) wheat compared to 91–101mg/100g after 1968, an average decrease close to 20% [7].  Similar declines in the mineral content of grains have been reported for zinc, iron, iodine and vitamin A. Deficiency is also observable in plants grown in low magnesium soil. They grow shorter, sparser root systems and paler foliage compared to their well-nourished counterparts.

It affects animals, too. Grass tetany occurs when large quantities of potassium fertilisers have been added to the soil. The potassium ions inhibit the absorption of magnesium ions by the grasses, leading to magnesium deficiency and subsequent muscle spasms in the grazing animal [7].

Medications, some of which are prescribed in conditions where magnesium deficiency was a co-factor can exacerbate magnesium deficiency. Protein-pump inhibitor medications for reflux worsen malabsorption, and loop diuretics and thiazide diuretics have been found to increase wasting of magnesium [2]. Ask your doctor to monitor your magnesium levels when taking these medications.

Magnesium as medicine

In the mountains of Slovenia an underground spring is a source of water containing or 1040mg/L of magnesium. It is so potent that it is called Donat Mg and it is marketed to relieve constipation. The magnesium in Donat Mg is in the form of magnesium sulfate, and together with sodium sulfate (also present in the spring’s water), it draws moisture into the intestinal matter and stimulates gut peristalsis. It is therefore recommended on the bottle that consumption is limited to 500mL/day [8]. In hospitals, magnesium is prescribed for constipation, especially for patients on opioid pain killers, and you may be familiar with the name Milk of Magnesia, which is one such laxative. High enough doses of magnesium will eventuate in diarrhoea which inhibits vital nutrient absorption, so the dosage needs to be reduced immediately, should that occur.

In a nutshell

With magnesium depleted from our soils and in scare amounts in metropolitan tap water, the likelihood of you being deficient in magnesium is apparent. Add to that a diet lacking in nuts, seeds, greens and beans and it is reasonable to assume you are not meeting your daily magnesium needs. Magnesium deficiency can show itself with symptoms such as agitation, confusion, anxiety, irritability, restless leg syndrome, muscle spasms and weakness, and sleep disorders. Even without these symptoms, if you are tired of feeling tired, or of suffering with sluggishness, make some changes to your diet and water intake. In addition, supplement with quality topical applications or water soluble oral magnesium.  Besides feeling better, you will be taking a positive step towards safeguarding yourself from chronic diseases including heart disease and diabetes.

For more magnesium information, see previous blog posts Magnesium. Know What You’re Missing!, Transdermal Magnesium, and Mineral Waters and Magnesium.

Photo credit: fdecomite via VisualHunt / CC BY

1. Higdon, J., V. Drake, and B. Delage. Magnesium. 2001 October 2013 [cited 2017 27 March]; Available from: <lpi.oregonstate.edu/mic/minerals/magnesium>.
2. Supplements), N.-I.-o.-H.-O.o.D. Magnesium fact sheet for health professionals. 2016 11 February 2016 [cited 2017 27 March]; Available from: <www.ods.od.nih.gov/factsheets/Magnesium- HealthProfessional/ >.
3. Longmore, B., Magnesium – the quiet ubiquity, in Australian Pharmacist. 2016, Pharmaceutical Society of Australia Ltd. . p. 38-41.
4. Australian-NHMRC and New-Zealand-Ministry-of-Health, Magnesium, in Nutrient Reference Values for Australia and New Zealand Including Recommended Dietary Intakes. 2006, Australian National Health and Medical Research Council (NHMRC) Publications. p. 193-200.
5. Nica, A.S., et al., Magnesium supplementation in top athletes-effects and recommendations. Medicina Sportiva: Journal of Romanian Sports Medicine Society, 2015. 11(1): p. 2482.
6. Nutritional-Magnesium. Magnesium Health Overview. 2012 [cited 2017 28 March]; Available from: <https://www.youtube.com/watch?v=4MyiijnGZeU&t=1s>.
7. Guo, W., et al., Magnesium deficiency in plants: An urgent problem. The Crop Journal, 2016. 4(2): p. 83-91.
8. Zdravilišče-Rogaška. Effects (of Donat Mg). Medical Centre Rogaska 2015 [cited 2017 28 March ]; Available from: <http://www.rogaska-medical.com/en/donat-mg/effects>.

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