Magnesium and health

The relationship between magnesium and health is widely studied because of the importance of this essential nutrient in many body functions and the prevention of chronic diseases.

What is magnesium?

Magnesium is a mineral involved as a cofactor in many processes within the body, including metabolic functions (energy production, glucose breakdown, protein synthesis, RNA and DNA synthesis), bone development, immune and neuromuscular function (1, 2, 3). It’s also involved in the balance of calcium, sodium, potassium and antioxidants (1, 2, 4).

The total amount of magnesium in an adult is about 25 grams, of which 50-60% is located in the bones (1, 3) and about 0.3% in serum (2). This places magnesium as the fourth most abundant mineral in the body (2, 5).

The actual amount of magnesium in the body is dictated by how much is absorbed in the small intestine and how much is excreted in urine (1, 6). Absorption rates range from 24% to 76% (6) depending on the variety of factors, including the amount that is ingested (absorption increases when ingestion is low to keep levels up) and vitamin D status (1, 6). On the flip side, magnesium excretion is regulated to some extent by hormones such as oestrogen and parathyroid (6). In addition, there is an exchange of the magnesium stored in bones (1).

Recommended daily intake of magnesium

In Australia, the recommended daily intake (RDI) is (7):

Age group	Males RDI (mg/day)	Females RDI (mg/day)
1-3 years old	80	80
9-13 years old	240	240
14-18 years old	410	360
19-30 years old	400	310
31-50 years old	420	320
51-70 years old	420	320
>70 years old	420	320

Sources of magnesium

Food

Food sources of magnesium include fruits (e.g. dried fruits and bananas), vegetables (e.g. sundried tomatoes, spinach, seaweed, rocket, okra, kale, snow peas), whole grains (e.g. wheat bran and germ, uncooked oats, wholemeal or mixed grain breads, and cooked brown rice, quinoa, spelt, buckwheat, barley and millet), legumes (e.g. tofu, cooked or canned haricot beans, red kidney and lima beans, cooked or canned chickpeas), nuts (e.g. Brazil nuts, almonds, cashews, pine nuts, peanuts, peanut butter, hazelnuts, walnuts, pecans, pistachios and macadamias – note that some of these are not true nuts), seeds (e.g. pumpkin, linseed/flaxseed, sunflower, poppy, chia, tahini), some cheeses (e.g. Parmesan, Edam, cheddar, mozzarella, firm goat cheese), meat (e.g. chicken breast, veal, pork medallions/loin/rump steaks, lamb chops, mutton), seafood (e.g. oysters, mussels, abalone, anchovies, tuna, prawn, sardines, lobster, squid, snapper, trout, basa, tilapia, scallops, barramundi) and fortified foods (e.g. breakfast cereals) (1, 2, 5, 6, 8). It can also be found in tap and some mineral waters (1, 6). However, food processing reduces magnesium bioavailability (2, 6).

Supplements

Magnesium supplements come in either oral, intravenous or topical/intradermal forms (2). Oral supplements can be inorganic (e.g. oxide, sulphate) or organic (e.g. aspartate, citrate, lactate, chloride, orotate, taurate), which have better absorption (2, 5, 6). Topical and intradermal forms include magnesium oil and bath salts, which are thought to be absorbed through skin (2).

Oral supplements can cause gastrointestinal symptoms such as diarrhoea, nausea and vomiting (6).

Magnesium intake in Australia

As seen in my previous post nutrient reference values vs nutrient intake in Australia, only children 2-13 years old met the RDI for magnesium. This highlights the fact that most Australians are not eating enough whole foods, which are rich in this mineral (data from 9).

Measuring magnesium

Even though serum magnesium is the most common metric, it doesn’t necessarily reflect true levels in the body (2, 3, 5, 6). Instead, other tests such as levels in red blood cells (2, 3), ionized magnesium and magnesium loading (3, 6) seem to be more accurate.

Deficiency

Magnesium deficiency in healthy individuals is not common but it can happen. Some causes include low intake, conditions that compromise absorption through the gut (such as chronic diarrhoea, Chron’s disease, Coeliac disease), alcoholism and the use of some medications including diuretics, antacids and proton pump inhibitors. Symptoms of deficiency are non-specific and may include loss of appetite, nausea, vomiting, lethargy, fatigue weakness, muscle cramps, tremors, muscle spasms and cardiac arrhythmia (1, 6).

Toxicity

Hypermagnesemia or excess magnesium is rare and usually happens in patients with renal insufficiency who take supplemental magnesium. Too much magnesium can cause non-specific symptoms such as nausea, vomiting, lethargy and headaches, and can lead to death (1).

Magnesium and health

Diabetes and metabolic syndrome

Magnesium is important for glucose and insulin metabolism. The intake of magnesium-rich foods is inversely associated with risk and incidence of type-2 diabetes and the metabolic syndrome (5, 6). In addition, magnesium supplementation may improve insulin sensitivity (3, 6).

Vitamin D deficiency

Magnesium is required for the activation and proper function of vitamin D (2, 6), which is in turn is important for good health and athletic performance.

Cardiovascular health

Low levels of magnesium are associated with hypertension and atherosclerosis (6). Magnesium supplementation may help regulate blood pressure levels, especially in people who are deficient (5, 6). The effect is sometimes seen in systolic but not diastolic blood pressure (3).

Consumption of foods high in magnesium may improve blood lipid levels, i.e. lower LDL-cholesterol and triglycerides and increase HDL-cholesterol. Magnesium supplements may help reduce LDL-cholesterol and triglycerides in patients with high levels (5).

Magnesium intake is inversely correlated with risk of stroke (3, 4, 5) and atrial fibrillation after heart surgery (5).

In addition, insulin resistance and metabolic syndrome are risk factors for cardiovascular disease which are associated with magnesium consumption as mentioned above.

As a therapeutic agent, intravenous magnesium may be used in patients with ventricular tachycardia (10).

Brain and neurological conditions

Migraines are associated with low levels of magnesium and can be treated with magnesium supplementation in either oral or intravenous forms (3, 4, 6, 10).

Similarly, oral, transdermal or intravenous supplementation of magnesium may help with conditions characterised by chronic pain such as fibromyalgia (4).

Magnesium supplements may help in the treatment of attention deficit hyperactivity disorder (ADHD) due to the interaction between this mineral and the neurotransmitters associated with this condition (6).

Low magnesium levels are observed in Alzheimer’s Disease but it’s unclear the role of this nutrient in the development or treatment of this disease. However, scientists have found this to be the case when measuring levels with tests other than serum (e.g. in the cerebrospinal fluid, hair, plasma and red blood cells, ionized) (3, 4, 11).

Part of the damage sustained during traumatic brain injury is due to the depletion of magnesium and subsequent influx of calcium. Magnesium supplementation can help mitigate this damage when used as part of a comprehensive recovery protocol (12).

Other conditions

Preeclampsia is a condition that can occur during pregnancy and is characterised by high blood pressure. An effective treatment is magnesium sulphate supplementation (6, 10).

Intravenous magnesium can help in severe acute asthma (10).

Magnesium hydroxide and citrate are commonly used to relieve constipation, however there is not a lot of evidence supporting this supplement (10).

Summary and recommendations

Magnesium is an essential mineral needed for many body functions. Maintaining levels at or above the recommended daily intake can help prevent many conditions including chronic diseases. The best way to achieve this is to eat a diet rich in whole unprocessed foods. Supplementation is not always needed but it can help in the treatment of specific conditions. Talk to your doctor if you need more information.

References

1. Costello R, Wallace TC, Rosanoff A. Magnesium. Adv Nutr. 2016;7(1):199-201.
2. Razzaque MS. Magnesium: Are We Consuming Enough? Nutrients. 2018;10(12).
3. Volpe SL. Magnesium in disease prevention and overall health. Adv Nutr. 2013;4(3):378s-83s.
4. Kirkland AE, Sarlo GL, Holton KF. The Role of Magnesium in Neurological Disorders. Nutrients. 2018;10(6).
5. Rosique-Esteban N, Guasch-Ferré M, Hernández-Alonso P, Salas-Salvadó J. Dietary Magnesium and Cardiovascular Disease: A Review with Emphasis in Epidemiological Studies. Nutrients. 2018;10(2).
6. Gröber U, Schmidt J, Kisters K. Magnesium in Prevention and Therapy. Nutrients. 2015;7(9):8199-226.
7. National Health and Medical Research Council, Australian Government Department of Health and Ageing, New Zealand Ministry of Health. Nutrient Reference Values for Australia and New Zealand. Canberra: National Health and Medical Research Council; 2006
8. Food Standards Australia New Zealand (2019). Australian Food Composition Database – Release 1. Canberra: FSANZ. Available at www.foodstandards.gov.au
9. Australian Bureau of Statistics 2016, Australian Health Survey: Nutrition First Results – Foods and Nutrients, 2011–12 — Australia, ‘TABLE 1.1 Mean daily energy and nutrient intake’, data cube: Excel spreadsheet, cat. no. 4364.0.55.007, viewed 15 September 2020, https://www.abs.gov.au/ausstats/subscriber.nsf/log?openagent&Table%201%20Mean%20daily%20energy%20and%20nutrient%20intake.xls&4364.0.55.007&Data%20Cubes&C53378E733B57D2CCA257CD200146C93&0&2011-12&09.05.2014&Latest
10. Guerrera MP, Volpe SL, Mao JJ. Therapeutic uses of magnesium. American family physician. 2009;80(2):157-62.
11. Veronese N, Zurlo A, Solmi M, Luchini C, Trevisan C, Bano G, et al. Magnesium Status in Alzheimer’s Disease: A Systematic Review. American journal of Alzheimer’s disease and other dementias. 2016;31(3):208-13.
12. Sen AP, Gulati A. Use of magnesium in traumatic brain injury. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics. 2010;7(1):91-9.

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