Magnesium:The Definitive Guide

Magnesium: the definitive guide
Author Miriam Ferrer, PhDLast updated 7th February 2020
  • Ingredients & Nutrition

Magnesium: the definitive guide

This important mineral contributes to a healthy energy-yielding metabolism, the reduction of tiredness and fatigue, cell division, electrolyte balance, the nervous system, normal muscle function and the maintenance of bones and teeth. Yet even though it is found in many common foods, a lot of us are no longer getting enough. In this article we discuss why magnesium is so important and how you can boost your intake.

  • What is magnesium?
  • What is magnesium good for?
  • Why are people deficient in magnesium?
  • What are the effects of magnesium deficiency?
  • How can I increase my magnesium intake?
  • How much magnesium do I need?
  • Is it safe to take magnesium with prescription drugs?
  • The best magnesium supplements - what to look out for

What is magnesium?

Magnesium (named after Magnesia, the region of Greece, where it was first observed) is the eighth most common chemical element in the earth’s crust and the eleventh most common in the human body.

Recognised as a chemical element in 1755, magnesium was first isolated by pioneering chemist Sir Humphry Davy in 1808.1 However, people were aware that this vital mineral was beneficial to the human body as early as 1618, when a farmer from the English market town of Epsom realised that water from a bitter saline spring helped to heal cuts and rashes. It was later discovered that 'epsom salts' - which are still used to soothe sore muscles today - is actually magnesium sulphate.2

Magnesium is a micronutrient that is essential for life. In humans it is usually absorbed from foods such as whole grains, legumes and leafy vegetables. It is present in many elements of a traditional healthy diet.3

What is magnesium good for?

The human body depends on magnesium to function properly. This important mineral:

  • is present in every cell, and in hundreds of enzymes that speed biochemical reactions to sustain life
  • plays a key role in mitosis, the process by which our cells divide into identical copies to produce more cells for growth and repair
  • helps to produce energy and protein
  • contributes to regulating the heartbeat
  • maintains the strength of bones and teeth
  • regulates blood glucose
  • supports a healthy immune system1

Getting enough magnesium may help with a number of common complaints.

Energy, tiredness and fatigue

Magnesium is needed to make ATP, the molecule that gives cells the energy they need to function (i.e. it is essential for your metabolism). It is also required for the constant process of cell division that replaces dead cells with living ones. In these different ways, magnesium is a vital part of millions of chemical reactions that take place throughout the body - without enough, you will feel less energetic.

Magnesium is also important in recovery from strenuous exercise - for example, cycle racing - because it helps with the enzymatic reactions that affect muscle performance. It may maintain muscle integrity during the exercise too, protecting the muscles from damage.4

Muscle cramps and twitches

Magnesium and calcium are both needed for your muscles to function. Simply put, calcium enables them to contract and magnesium allows them to relax.

If you do not have enough magnesium this can cause your muscles to cramp or spasm because they cannot relax properly. Supplements containing the mineral are sometimes offered to help with these issues.5

Bone health

It is well known that calcium is needed to form strong and healthy bones, but magnesium is also essential. It is used to form the apatite crystals that are the main component of bone mineral and tooth enamel.

About 60% of magnesium in the body is stored in the bones, and too much or too little of it has a negative effect.

It may also be helpful for the role it plays in regulating two other nutrients which are important for forming and strengthening bones, calcium and vitamin D.6

Cardiovascular health

There is clear evidence the magnesium levels are associated with cardiovascular health, with deficiency increasing the chances of developing high blood pressure, type 2 diabetes, dyslipidemia, atherosclerosis, arrhythmias, and coronary artery disease.7

Research continues into the effectiveness of magnesium supplements to prevent and manage cardiovascular issues. Studies suggest that supplementation can reduce the likelihood of experiencing cardiac events such as heart attacks and strokes.8


Magnesium deficiency is common in people with type 2 diabetes, perhaps due to low and intakes and increased loss through urine. It has been related to the development of the disease and, among other negative effects, a lack of magnesium increases insulin resistance.

Most studies have shown that magnesium supplementation improves the metabolic profile of people with diabetes.9


Magnesium deficiency is associated with a whole range of psychological issues including agitation, anxiety, irritability, confusion, poor sleep and depression.

Some studies have shown that magnesium supplementation could play a useful role in treating depression and anxiety.101112


People who suffer from migraines, cluster headaches and menstrual migraines often have low levels of magnesium.

Research data suggest that magnesium supplementation might be helpful in preventing and reducing the frequency of migraines, but more data is needed.131415

Immune Health

Magnesium plays an important role in both innate and acquired immune response. Deficiency may weaken resistance to illnesses and allergic reactions.1617

Why are people deficient in magnesium?

The NHS recommends that adult men from 19-64 need 300mg of magnesium per day. Adult women need 270mg. Older and younger people require different amounts.18

A person can become deficient for three reasons. Either they are not absorbing enough, are not getting enough from their diet, or are excreting too much from their kidneys.

In a UK study of 8,000 individuals conducted by testing company Health Check, around 70 per cent of participants were found to have low magnesium levels. Meanwhile, the UK Government's National Diet and Nutrition Survey found that the majority of children and adolescents were also failing to reach recommended levels, with teenage girls particularly affected.19

The population-wide increase in insufficiency and deficiency has been linked to modern intensive farming techniques which strip micronutrients from the soil, increased consumption of processed food, and the use of some pharmaceutical products including drugs to treat heartburn.20

The following groups are more at-risk of magnesium deficiency:

  • Older people struggle to absorb as much magnesium and they excrete more of it, so the increase in deficiency across the UK may also be linked to the ageing population. This group is also more likely to suffer from health issues and take medications that increase the risk of deficiency.
  • Alcoholics and very heavy drinkers often suffer from related conditions that increase the risk of deficiency, including gastrointestinal problems, damage to the liver and kidneys and phosphate deficiency.
  • Type 2 diabetics and people with increased insulin resistance can experience greater excretion of magnesium because of more frequent urination.
  • People with gastrointestinal diseases that make absorption in the gut more difficult, including those with celiac and Crohn's disease.
  • People suffering from kidney issues. Deficiency is often an early sign of problems such as chronic kidney disease.21

What are the effects of magnesium deficiency?

Magnesium plays a role in so many bodily processes that the symptoms of deficiency are also quite broad. These symptoms can include:

  • Tiredness and fatigue
  • Headaches
  • Trouble sleeping
  • Mood swings
  • Weakness
  • Muscle cramps
  • Low potassium levels
  • Irritability of the nervous system
  • Irregular heartbeat
  • Due to magnesium's role in the carbohydrate metabolism the deficiency can be either a cause of, or a result of, insulin resistance

In extreme and prolonged cases the health issues caused by magnesium deficiency can be severe and even dangerous.21

How can I increase my magnesium intake?

Getting enough magnesium is critical but unfortunately it is difficult to absorb, especially for people aged 55 and over.

Dietary changes are a good place to start. Fortunately, magnesium is present in a lot of common foods. People who want to increase dietary consumption of magnesium should try eating more high fibre foods including cereal and whole grains, and dark leafy greens - though because some compounds in these foods can also inhibit absorption of magnesium, you may have to eat more than expected. Here are a few other popular foods that are high in magnesium:

  • Avocados
  • Bananas
  • Beans including black beans, soybeans and kidney beans
  • Brown rice
  • Chickpeas
  • Dark chocolate
  • Fish including tuna and mackerel
  • Nuts and seeds including peanuts and cashews
  • Porridge
  • Potato skin
  • Yoghurt and other milk products3

To support improved dietary choices, a highly bioavailable supplement allows for significant absorption of this important mineral.

How much magnesium do I need?

According to the NHS:

  • Men over the age of 19 need 300mg a day
  • Women over the age of 19 need 270mg a day

Is it safe to take magnesium with prescription drugs?

Magnesium can affect the absorption of some medications including some varieties of antibiotics and statins.

As always, you should consult your doctor or pharmacist before taking a nutritional supplement to make sure that it is suitable.

The best magnesium supplements - what to look out for

When looking for an effective magnesium supplement you should look carefully at claims about absorption (bioavailability).

Magnesium can be difficult to absorb, especially for people over the age of 55. Yet taking more is sometimes not the best approach, as too much of the mineral can cause some unpleasant side effects. For that reason it is best to find a bioavailable supplement so you can experience the benefits without a surfeit of the mineral itself.

Many popular magnesium supplements on the market contain a chemical compound called magnesium oxide. However, it is also the most difficult for the body to absorb.22

Magnesium lactate is a similar compound that is used in some supplements, in which the magnesium is paired with lactic acid instead. This makes it easier for the body to absorb - two times easier than magnesium oxide - and ensures that less is needed to achieve the same results.


  1. Jahnen-Dechent W, Ketteler M. Magnesium basics. Clin Kidney J. 2012;5(Suppl 1):i3–i14. doi:10.1093
  4. Córdova A, Mielgo-Ayuso J, Roche E, Caballero-García A, Fernandez-Lázaro D. Impact of Magnesium Supplementation in Muscle Damage of Professional Cyclists Competing in a Stage Race. Nutrients 2019, 11(8), 1927
  5. Bilbey DL, Prabhakaran VM. Muscle cramps and magnesium deficiency: case reports. Can Fam Physician. 1996 Jul;42:1348-51
  6. Castiglioni S, Cazzaniga A, Albisetti W, Maier JA. Magnesium and osteoporosis: current state of knowledge and future research directions. Nutrients. 2013;5(8):3022–3033. Published 2013 Jul 31. doi:10.3390/nu5083022
  7. Severino P, Netti L, Mariani MV, et al. Prevention of Cardiovascular Disease: Screening for Magnesium Deficiency. Cardiol Res Pract. 2019;2019:4874921. Published 2019 May 2. doi:10.1155/2019/4874921
  8. DiNicolantonio JJ, Liu J, O’Keefe JH Magnesium for the prevention and treatment of cardiovascular diseaseOpen Heart 2018;5:e000775. doi: 10.1136/openhrt-2018-000775
  9. Barbagallo M, Dominguez LJ. Magnesium and type 2 diabetes. World J Diabetes. 2015;6(10):1152–1157. doi:10.4239/wjd.v6.i10.1152
  10. Tarleton EK, Littenberg B, MacLean CD, Kennedy AG, Daley C (2017) Role of magnesium supplementation in the treatment of depression: A randomized clinical trial. PLOS ONE 12(6): e0180067.
  11. Eby GA, Eby KL. Rapid recovery from major depression using magnesium treatment. Med Hypotheses. 2006;67(2):362-70. Epub 2006 Mar 20
  12. Kirkland AE, Sarlo GL, Holton KF. The Role of Magnesium in Neurological Disorders. Nutrients. 2018;10(6):730. Published 2018 Jun 6. doi:10.3390/nu10060730
  13. Von Luckner A, Riederer F. Magnesium in Migraine Prophylaxis-Is There an Evidence-Based Rationale?A Systematic Review. Headache. 2018;58(2):199–209. doi:10.1111/head.13217
  14. Mauskop A, Altura BT, Altura BM. Serum ionized magnesium levels and serum ionized calcium/ionized magnesium ratios in women with menstrual migraine. Headache. 2002;42(4):242-248.
  15. Peikert A, Wilimzig C, Köhne-Volland R. Prophylaxis of migraine with oral magnesium: results from a prospective, multi-center, placebo-controlled and double-blind randomized study. Cephalalgia. 1996;16(4):257-263.
  16. Tam M, Gómez S, González-Gross M, Marcos A. Possible roles of magnesium on the immune system. Eur J Clin Nutr. 2003 Oct;57(10):1193-7.
  17. Galland L. Magnesium and immune function: an overview. Magnesium. 1988;7(5-6):290-9.
  21. Al Alawi AM, Majoni SW, Falhammar H. Magnesium and Human Health: Perspectives and Research Directions. Int J Endocrinol. 2018;2018:9041694. Published 2018 Apr 16. doi:10.1155/2018/9041694
  22. Jones, A., Greb, A. Vasilakos, J. & Longstreet, D. (2015) Bioavailability of magnesium supplements. Center for Magnesium Education and Research